WASHING OND 2052 1 Ibull 1

A PRIMARY 1 U BJ C Tri u l t re g

A H 1 0 0 0 0 0 -G 7 2 CLASSI- r FICAT ION B S E C O N D A R Y - bull

Pests of lants--Philippines 2 TITLE AND SUBTITLE

Estimating population parameters of the ricefield rat (Rattus rattus mindanensis Mearns)

3 AUTHOR(S)

BenignoEA

4 DOCUMENT DATE -- oNUMBER OF PAGES 16 ARC NUMBER 1972 I 58po ARC

7 REFERENCE ORGANIZATION NAME AND ADDRESS

Interior

8 SUPPLEMENTARY NOTES (Sponaorlnj Organlxallon Publishers Avallabillfy)

(ThesisMS--Univof the Philippines))

9ABSTRACT

SBEST COPY AVAILABLE

10 CONTROL NUMBER 11 PRICE OF DOCUMENTL

PN-RA- 586

12 DESCRIPTORSEstimates Seasial vaiatins 13 PROJECT NUMBER

Philippines 14 CONTRACT NUMBER Populations PASA RA(ID)l-67 Res Rats 18TYPE OF DOCUMENT

AID 090-1 (4-74)

ESTIMATING POPULATION PARAMETERS OF THE RICEFIELD IRAT (RATTUSRATTUS MINDANENSIS MEARNS)

EDWIN A BENIGNO

SUBMITTErD TO TtIB udIDUATE FACULTY OF TIH COLLEGE OF AGRICULTURE UlIVERSITY OF THE PHILIPPINES IN

PARTIAL FULFILI4ENT OF THE rQiTIREMENTS FOR THE DEGREE OF

MASTER OF SCIENCE (ApplieJ oology)

November 1972

BIOGWR~qC -DATA

The author was born in-Laoa City on September 4He is theonetson of Felixein eibaetoand reiaAaoI~qIn1954 the familymigrated to Pag n Citywhere he tookc his primar education at thePagadian Central Elementary School Later hey settled inDavao Citywhere he finished his intermediate (with honors) and secondary (with

honors) courses at the Davao Central Elementary School in 1961 and University of Mindanao (High School) in 1965 respectively

He was admitted to the University of the Philippines College ofAgriculture as an entrance scholar At various times during hisUndergraduate study he was a university scholar college scholar and an UPCA undergraduate fellow He finished his Bachelor of Science inAgriculture (cum laude) degree in 1969 In the same year he wasawarded a research assistantshipby the Rodent Research Center (NEO-USAID) Scholarship Program to pursue his M S degree in this university

EDWIN A BENIGNO

DEDICATION

This work is lovingly dedicated to my parents and my brothers for their endless encouragement and inspiration throighout my studies

AOKNOWEDG0 VT

The author appreciates the constructive Oriticisms made by the

members ofhis guidance committee Prof P J Alfonso (adviser)

Dr V G Momongan Dr FFSanchez Dr M B de Ramos and

Mr S M Alviar The author isalso indebted to Dr I P David for

his unselfish suggestions in the planning of this work

The cooperation and assistance extended by the following will

never be forgotten

The NEC-USAID for the study grant the director and the staff of

the Rodent Research Center the constituents of the Baybay National

College of Agriculture and Technology headed by Messrs BRomerosa

and R Alcala principal and farm manager respectively the landowners

auLL tenants of the study plots in Siniloan Laguna

To them and zo all those who in one way or another have made

thin studv nossible the amthrr expresses his profound gratitude

TABLE OF CONTENTS

INTRODUCTION

REVIEW OF LITERATURE

Trap-mark-recapture method

Quadrat method

Trapline index

Removal technique

Change-in-ratio estimate

Population structural model

Forecasting method

Home ranzo moensiiramont

MATERIALS AND 1THODS

Wet season study

Dry scason study

Radio-tracking

Home range and movements

Populatipn densities

RESULTS AND DISCUSSION

Home ranges and movements

Population densities

Trappability

Capture-rlease-recapbure technique casea

LITERATURE CITED

APPENDIX

Page

1

2

3

7

7

8

9

10

i0

11

14

15

25

17

17

19

19

19

27

32

study 36

41

48

LIST OF TABLES

-Table1 Page

1Movement ofs marked-rats deteed by recapturo method 2-1

lb movoement of radio-monitored rate 26

2a let soason rocapture data 28

2b Dry season recapturc data 28 3ao Monthly wet season densities as estimated

by the Petersen method 29 3b Monthly dry season densities as dete rmined

by different models based on the capture-release-recapture technique 29

4 Dry season population parameters estimated by Jollys stochastic model 32

LIST OF ILLUSTRATIONS

Figure Page

1 Wet 805 -1study area with traps set16

alk- Ydikces 1

2 Dry -esrnstudy gridt 18

3a Apparent home ranges of individlu ly marked rat based upon wet season recapture data 20

3bjApparent home ranges of individually marked rats based upon dry season recapture data 21

4a- Inclusive boundary strip home ranges of six

radio-monitorod rats 23

4b Movoment patetrns of radio-monitored rats 25

5 MontEly population densi ty par hectare 31

6 Distribubion of1 catch amonG t apo aet in g ~ 3

ABSTRACT

Benigno Edwin Abalos University of the Philippines November

1972 Estimating Population Parameters of the Ricefield Rat (Rattus

rattus mindanensis Mearns) Major Professor Pablo S Alfonso

Livetrapping was conducted twice a month for two crop seasons in

a selected rice growing area inSiniloan Laguna Data for the

estimation of population parameters were obtained independently for

eaohseason by moans of the capture release and recapture method

Monthly population density per hectare and subsequent damage to

rice was greater during the wet season In both seasons density

increased toward maturity of the crop Density was negati-ely

corrOlated with the oropcrtion of male0 Li the monthly samples while

nu eignifiant correlation ras found betreen density aad the

proportion o jaeiilos i the 5unple

Juvenilee were more mobile nd xcjibi ed lar-er home ranges than

Itadults adul males and femaes were equally Io tile favesting and X-nprepcartion withovt Lcorpert -n control did not eert immediate

arid Gignifiuant d-ioplacement effect on the population Trap location animal behavior and the prevailing I he

conditions offeted traipablity resulting in vatkbl -rp api bull n even

Within the samIiztxpping perlorl T le prcA m of few reoaptuares1 of mlarked a iwblind te that tine tapC1re release

and ecaptrt Sthrd alone ma b prnctical for AOos Iri

piira4Ion

INTRODUCTION

The study of animal poptilationshas recently received cons erab4 attention Many ttempts have been made to describe the structure of

agiven population quantitatively Consequently more refined

statistical methods have to be evolved to obtain accurate estimates of

the different parameters characteristic of the population

Population parameters in turn provide one of the bases for sound -pest management and maximum utilization of animals of importance to

man Allen (1949) further stressed the need for such parmeters lie

blamed the lack of fast and accurate estimation procedures for the sloW

progress in efficient wildlife management The statement holds

especially true for vertebrate poat management in the Philippines

ViUh ibe iiitantton to curtribute Li th- effort to renedy theo situation

III ootidy Jualutucted at thui Der arrent of ritomo3rgy and Applio-

Zoology and in the rice flelds of Sinloan Lagtuna frcm Scpterabe

971 tn June 1972

The me- of this study reoi1ctiv

1p T cjppkI unctr typical -Vicefiold condltiors of at -shy

-in~esta~ion a ila~b-le echni cjues for ust rig 5oolai Jxat parwietcs

Such 9s opation de saty) oirvival rates bullanoi homeo rnge

2mou Tmltc oiooc are saitte- L1 the 41ud~y of 1ociiz

roden-b pop41~atirnsfishy

2

REVIEW1 OFLITERATURE

populatibn is ever static Itmay attain equilibriui but at

any given time itlis the resul~t of the interaction of three generalized

forces 4ecognized by Davis (1953a)s

Reproduction tends to increase the population mortality tends to decrease itandmovements tend to increase it or decrease it depending upon the net result of immigration and emigration

Lotka (1925) expressed the relationship among these forces conveniently

in the equation

k(-D)

Where

-N = number ofindividuals inthe population

B- birth andor immigration

S= death andor emigration

wuxitoft3me

k= oa constant

The population size (N) is therefore a convenient inde of the

state of- a popflation at any gvntmThere is atpresent a

number of techniques for estimating this important parameter

Andrewartha (1961) Emlen Stokes andDavis (1949) Olassified

the different ostimation techniques as measurements of absolute

density (diroct measurement) and of relative density (indirect

measurement)y density being defined as the number of animals in ashy

given area Kucheruk (1964) discussed them as indirect direcptan

BIOGWR~qC -DATA

The author was born in-Laoa City on September 4He is theonetson of Felixein eibaetoand reiaAaoI~qIn1954 the familymigrated to Pag n Citywhere he tookc his primar education at thePagadian Central Elementary School Later hey settled inDavao Citywhere he finished his intermediate (with honors) and secondary (with

honors) courses at the Davao Central Elementary School in 1961 and University of Mindanao (High School) in 1965 respectively

He was admitted to the University of the Philippines College ofAgriculture as an entrance scholar At various times during hisUndergraduate study he was a university scholar college scholar and an UPCA undergraduate fellow He finished his Bachelor of Science inAgriculture (cum laude) degree in 1969 In the same year he wasawarded a research assistantshipby the Rodent Research Center (NEO-USAID) Scholarship Program to pursue his M S degree in this university

EDWIN A BENIGNO

DEDICATION

This work is lovingly dedicated to my parents and my brothers for their endless encouragement and inspiration throighout my studies

AOKNOWEDG0 VT

The author appreciates the constructive Oriticisms made by the

members ofhis guidance committee Prof P J Alfonso (adviser)

Dr V G Momongan Dr FFSanchez Dr M B de Ramos and

Mr S M Alviar The author isalso indebted to Dr I P David for

his unselfish suggestions in the planning of this work

The cooperation and assistance extended by the following will

never be forgotten

The NEC-USAID for the study grant the director and the staff of

the Rodent Research Center the constituents of the Baybay National

College of Agriculture and Technology headed by Messrs BRomerosa

and R Alcala principal and farm manager respectively the landowners

auLL tenants of the study plots in Siniloan Laguna

To them and zo all those who in one way or another have made

thin studv nossible the amthrr expresses his profound gratitude

TABLE OF CONTENTS

INTRODUCTION

REVIEW OF LITERATURE

Trap-mark-recapture method

Quadrat method

Trapline index

Removal technique

Change-in-ratio estimate

Population structural model

Forecasting method

Home ranzo moensiiramont

MATERIALS AND 1THODS

Wet season study

Dry scason study

Radio-tracking

Home range and movements

Populatipn densities

RESULTS AND DISCUSSION

Home ranges and movements

Population densities

Trappability

Capture-rlease-recapbure technique casea

LITERATURE CITED

APPENDIX

Page

1

2

3

7

7

8

9

10

i0

11

14

15

25

17

17

19

19

19

27

32

study 36

41

48

LIST OF TABLES

-Table1 Page

1Movement ofs marked-rats deteed by recapturo method 2-1

lb movoement of radio-monitored rate 26

2a let soason rocapture data 28

2b Dry season recapturc data 28 3ao Monthly wet season densities as estimated

by the Petersen method 29 3b Monthly dry season densities as dete rmined

by different models based on the capture-release-recapture technique 29

4 Dry season population parameters estimated by Jollys stochastic model 32

LIST OF ILLUSTRATIONS

Figure Page

1 Wet 805 -1study area with traps set16

alk- Ydikces 1

2 Dry -esrnstudy gridt 18

3a Apparent home ranges of individlu ly marked rat based upon wet season recapture data 20

3bjApparent home ranges of individually marked rats based upon dry season recapture data 21

4a- Inclusive boundary strip home ranges of six

radio-monitorod rats 23

4b Movoment patetrns of radio-monitored rats 25

5 MontEly population densi ty par hectare 31

6 Distribubion of1 catch amonG t apo aet in g ~ 3

ABSTRACT

Benigno Edwin Abalos University of the Philippines November

1972 Estimating Population Parameters of the Ricefield Rat (Rattus

rattus mindanensis Mearns) Major Professor Pablo S Alfonso

Livetrapping was conducted twice a month for two crop seasons in

a selected rice growing area inSiniloan Laguna Data for the

estimation of population parameters were obtained independently for

eaohseason by moans of the capture release and recapture method

Monthly population density per hectare and subsequent damage to

rice was greater during the wet season In both seasons density

increased toward maturity of the crop Density was negati-ely

corrOlated with the oropcrtion of male0 Li the monthly samples while

nu eignifiant correlation ras found betreen density aad the

proportion o jaeiilos i the 5unple

Juvenilee were more mobile nd xcjibi ed lar-er home ranges than

Itadults adul males and femaes were equally Io tile favesting and X-nprepcartion withovt Lcorpert -n control did not eert immediate

arid Gignifiuant d-ioplacement effect on the population Trap location animal behavior and the prevailing I he

conditions offeted traipablity resulting in vatkbl -rp api bull n even

Within the samIiztxpping perlorl T le prcA m of few reoaptuares1 of mlarked a iwblind te that tine tapC1re release

and ecaptrt Sthrd alone ma b prnctical for AOos Iri

piira4Ion

INTRODUCTION

The study of animal poptilationshas recently received cons erab4 attention Many ttempts have been made to describe the structure of

agiven population quantitatively Consequently more refined

statistical methods have to be evolved to obtain accurate estimates of

the different parameters characteristic of the population

Population parameters in turn provide one of the bases for sound -pest management and maximum utilization of animals of importance to

man Allen (1949) further stressed the need for such parmeters lie

blamed the lack of fast and accurate estimation procedures for the sloW

progress in efficient wildlife management The statement holds

especially true for vertebrate poat management in the Philippines

ViUh ibe iiitantton to curtribute Li th- effort to renedy theo situation

III ootidy Jualutucted at thui Der arrent of ritomo3rgy and Applio-

Zoology and in the rice flelds of Sinloan Lagtuna frcm Scpterabe

971 tn June 1972

The me- of this study reoi1ctiv

1p T cjppkI unctr typical -Vicefiold condltiors of at -shy

-in~esta~ion a ila~b-le echni cjues for ust rig 5oolai Jxat parwietcs

Such 9s opation de saty) oirvival rates bullanoi homeo rnge

2mou Tmltc oiooc are saitte- L1 the 41ud~y of 1ociiz

roden-b pop41~atirnsfishy

2

REVIEW1 OFLITERATURE

populatibn is ever static Itmay attain equilibriui but at

any given time itlis the resul~t of the interaction of three generalized

forces 4ecognized by Davis (1953a)s

Reproduction tends to increase the population mortality tends to decrease itandmovements tend to increase it or decrease it depending upon the net result of immigration and emigration

Lotka (1925) expressed the relationship among these forces conveniently

in the equation

k(-D)

Where

-N = number ofindividuals inthe population

B- birth andor immigration

S= death andor emigration

wuxitoft3me

k= oa constant

The population size (N) is therefore a convenient inde of the

state of- a popflation at any gvntmThere is atpresent a

number of techniques for estimating this important parameter

Andrewartha (1961) Emlen Stokes andDavis (1949) Olassified

the different ostimation techniques as measurements of absolute

density (diroct measurement) and of relative density (indirect

measurement)y density being defined as the number of animals in ashy

given area Kucheruk (1964) discussed them as indirect direcptan

DEDICATION

This work is lovingly dedicated to my parents and my brothers for their endless encouragement and inspiration throighout my studies

AOKNOWEDG0 VT

The author appreciates the constructive Oriticisms made by the

members ofhis guidance committee Prof P J Alfonso (adviser)

Dr V G Momongan Dr FFSanchez Dr M B de Ramos and

Mr S M Alviar The author isalso indebted to Dr I P David for

his unselfish suggestions in the planning of this work

The cooperation and assistance extended by the following will

never be forgotten

The NEC-USAID for the study grant the director and the staff of

the Rodent Research Center the constituents of the Baybay National

College of Agriculture and Technology headed by Messrs BRomerosa

and R Alcala principal and farm manager respectively the landowners

auLL tenants of the study plots in Siniloan Laguna

To them and zo all those who in one way or another have made

thin studv nossible the amthrr expresses his profound gratitude

TABLE OF CONTENTS

INTRODUCTION

REVIEW OF LITERATURE

Trap-mark-recapture method

Quadrat method

Trapline index

Removal technique

Change-in-ratio estimate

Population structural model

Forecasting method

Home ranzo moensiiramont

MATERIALS AND 1THODS

Wet season study

Dry scason study

Radio-tracking

Home range and movements

Populatipn densities

RESULTS AND DISCUSSION

Home ranges and movements

Population densities

Trappability

Capture-rlease-recapbure technique casea

LITERATURE CITED

APPENDIX

Page

1

2

3

7

7

8

9

10

i0

11

14

15

25

17

17

19

19

19

27

32

study 36

41

48

LIST OF TABLES

-Table1 Page

1Movement ofs marked-rats deteed by recapturo method 2-1

lb movoement of radio-monitored rate 26

2a let soason rocapture data 28

2b Dry season recapturc data 28 3ao Monthly wet season densities as estimated

by the Petersen method 29 3b Monthly dry season densities as dete rmined

by different models based on the capture-release-recapture technique 29

4 Dry season population parameters estimated by Jollys stochastic model 32

LIST OF ILLUSTRATIONS

Figure Page

1 Wet 805 -1study area with traps set16

alk- Ydikces 1

2 Dry -esrnstudy gridt 18

3a Apparent home ranges of individlu ly marked rat based upon wet season recapture data 20

3bjApparent home ranges of individually marked rats based upon dry season recapture data 21

4a- Inclusive boundary strip home ranges of six

radio-monitorod rats 23

4b Movoment patetrns of radio-monitored rats 25

5 MontEly population densi ty par hectare 31

6 Distribubion of1 catch amonG t apo aet in g ~ 3

ABSTRACT

Benigno Edwin Abalos University of the Philippines November

1972 Estimating Population Parameters of the Ricefield Rat (Rattus

rattus mindanensis Mearns) Major Professor Pablo S Alfonso

Livetrapping was conducted twice a month for two crop seasons in

a selected rice growing area inSiniloan Laguna Data for the

estimation of population parameters were obtained independently for

eaohseason by moans of the capture release and recapture method

Monthly population density per hectare and subsequent damage to

rice was greater during the wet season In both seasons density

increased toward maturity of the crop Density was negati-ely

corrOlated with the oropcrtion of male0 Li the monthly samples while

nu eignifiant correlation ras found betreen density aad the

proportion o jaeiilos i the 5unple

Juvenilee were more mobile nd xcjibi ed lar-er home ranges than

Itadults adul males and femaes were equally Io tile favesting and X-nprepcartion withovt Lcorpert -n control did not eert immediate

arid Gignifiuant d-ioplacement effect on the population Trap location animal behavior and the prevailing I he

conditions offeted traipablity resulting in vatkbl -rp api bull n even

Within the samIiztxpping perlorl T le prcA m of few reoaptuares1 of mlarked a iwblind te that tine tapC1re release

and ecaptrt Sthrd alone ma b prnctical for AOos Iri

piira4Ion

INTRODUCTION

The study of animal poptilationshas recently received cons erab4 attention Many ttempts have been made to describe the structure of

agiven population quantitatively Consequently more refined

statistical methods have to be evolved to obtain accurate estimates of

the different parameters characteristic of the population

Population parameters in turn provide one of the bases for sound -pest management and maximum utilization of animals of importance to

man Allen (1949) further stressed the need for such parmeters lie

blamed the lack of fast and accurate estimation procedures for the sloW

progress in efficient wildlife management The statement holds

especially true for vertebrate poat management in the Philippines

ViUh ibe iiitantton to curtribute Li th- effort to renedy theo situation

III ootidy Jualutucted at thui Der arrent of ritomo3rgy and Applio-

Zoology and in the rice flelds of Sinloan Lagtuna frcm Scpterabe

971 tn June 1972

The me- of this study reoi1ctiv

1p T cjppkI unctr typical -Vicefiold condltiors of at -shy

-in~esta~ion a ila~b-le echni cjues for ust rig 5oolai Jxat parwietcs

Such 9s opation de saty) oirvival rates bullanoi homeo rnge

2mou Tmltc oiooc are saitte- L1 the 41ud~y of 1ociiz

roden-b pop41~atirnsfishy

2

REVIEW1 OFLITERATURE

populatibn is ever static Itmay attain equilibriui but at

any given time itlis the resul~t of the interaction of three generalized

forces 4ecognized by Davis (1953a)s

Reproduction tends to increase the population mortality tends to decrease itandmovements tend to increase it or decrease it depending upon the net result of immigration and emigration

Lotka (1925) expressed the relationship among these forces conveniently

in the equation

k(-D)

Where

-N = number ofindividuals inthe population

B- birth andor immigration

S= death andor emigration

wuxitoft3me

k= oa constant

The population size (N) is therefore a convenient inde of the

state of- a popflation at any gvntmThere is atpresent a

number of techniques for estimating this important parameter

Andrewartha (1961) Emlen Stokes andDavis (1949) Olassified

the different ostimation techniques as measurements of absolute

density (diroct measurement) and of relative density (indirect

measurement)y density being defined as the number of animals in ashy

given area Kucheruk (1964) discussed them as indirect direcptan

AOKNOWEDG0 VT

The author appreciates the constructive Oriticisms made by the

members ofhis guidance committee Prof P J Alfonso (adviser)

Dr V G Momongan Dr FFSanchez Dr M B de Ramos and

Mr S M Alviar The author isalso indebted to Dr I P David for

his unselfish suggestions in the planning of this work

The cooperation and assistance extended by the following will

never be forgotten

The NEC-USAID for the study grant the director and the staff of

the Rodent Research Center the constituents of the Baybay National

College of Agriculture and Technology headed by Messrs BRomerosa

and R Alcala principal and farm manager respectively the landowners

auLL tenants of the study plots in Siniloan Laguna

To them and zo all those who in one way or another have made

thin studv nossible the amthrr expresses his profound gratitude

TABLE OF CONTENTS

INTRODUCTION

REVIEW OF LITERATURE

Trap-mark-recapture method

Quadrat method

Trapline index

Removal technique

Change-in-ratio estimate

Population structural model

Forecasting method

Home ranzo moensiiramont

MATERIALS AND 1THODS

Wet season study

Dry scason study

Radio-tracking

Home range and movements

Populatipn densities

RESULTS AND DISCUSSION

Home ranges and movements

Population densities

Trappability

Capture-rlease-recapbure technique casea

LITERATURE CITED

APPENDIX

Page

1

2

3

7

7

8

9

10

i0

11

14

15

25

17

17

19

19

19

27

32

study 36

41

48

LIST OF TABLES

-Table1 Page

1Movement ofs marked-rats deteed by recapturo method 2-1

lb movoement of radio-monitored rate 26

2a let soason rocapture data 28

2b Dry season recapturc data 28 3ao Monthly wet season densities as estimated

by the Petersen method 29 3b Monthly dry season densities as dete rmined

by different models based on the capture-release-recapture technique 29

4 Dry season population parameters estimated by Jollys stochastic model 32

LIST OF ILLUSTRATIONS

Figure Page

1 Wet 805 -1study area with traps set16

alk- Ydikces 1

2 Dry -esrnstudy gridt 18

3a Apparent home ranges of individlu ly marked rat based upon wet season recapture data 20

3bjApparent home ranges of individually marked rats based upon dry season recapture data 21

4a- Inclusive boundary strip home ranges of six

radio-monitorod rats 23

4b Movoment patetrns of radio-monitored rats 25

5 MontEly population densi ty par hectare 31

6 Distribubion of1 catch amonG t apo aet in g ~ 3

ABSTRACT

Benigno Edwin Abalos University of the Philippines November

1972 Estimating Population Parameters of the Ricefield Rat (Rattus

rattus mindanensis Mearns) Major Professor Pablo S Alfonso

Livetrapping was conducted twice a month for two crop seasons in

a selected rice growing area inSiniloan Laguna Data for the

estimation of population parameters were obtained independently for

eaohseason by moans of the capture release and recapture method

Monthly population density per hectare and subsequent damage to

rice was greater during the wet season In both seasons density

increased toward maturity of the crop Density was negati-ely

corrOlated with the oropcrtion of male0 Li the monthly samples while

nu eignifiant correlation ras found betreen density aad the

proportion o jaeiilos i the 5unple

Juvenilee were more mobile nd xcjibi ed lar-er home ranges than

Itadults adul males and femaes were equally Io tile favesting and X-nprepcartion withovt Lcorpert -n control did not eert immediate

arid Gignifiuant d-ioplacement effect on the population Trap location animal behavior and the prevailing I he

conditions offeted traipablity resulting in vatkbl -rp api bull n even

Within the samIiztxpping perlorl T le prcA m of few reoaptuares1 of mlarked a iwblind te that tine tapC1re release

and ecaptrt Sthrd alone ma b prnctical for AOos Iri

piira4Ion

INTRODUCTION

The study of animal poptilationshas recently received cons erab4 attention Many ttempts have been made to describe the structure of

agiven population quantitatively Consequently more refined

statistical methods have to be evolved to obtain accurate estimates of

the different parameters characteristic of the population

Population parameters in turn provide one of the bases for sound -pest management and maximum utilization of animals of importance to

man Allen (1949) further stressed the need for such parmeters lie

blamed the lack of fast and accurate estimation procedures for the sloW

progress in efficient wildlife management The statement holds

especially true for vertebrate poat management in the Philippines

ViUh ibe iiitantton to curtribute Li th- effort to renedy theo situation

III ootidy Jualutucted at thui Der arrent of ritomo3rgy and Applio-

Zoology and in the rice flelds of Sinloan Lagtuna frcm Scpterabe

971 tn June 1972

The me- of this study reoi1ctiv

1p T cjppkI unctr typical -Vicefiold condltiors of at -shy

-in~esta~ion a ila~b-le echni cjues for ust rig 5oolai Jxat parwietcs

Such 9s opation de saty) oirvival rates bullanoi homeo rnge

2mou Tmltc oiooc are saitte- L1 the 41ud~y of 1ociiz

roden-b pop41~atirnsfishy

2

REVIEW1 OFLITERATURE

populatibn is ever static Itmay attain equilibriui but at

any given time itlis the resul~t of the interaction of three generalized

forces 4ecognized by Davis (1953a)s

Reproduction tends to increase the population mortality tends to decrease itandmovements tend to increase it or decrease it depending upon the net result of immigration and emigration

Lotka (1925) expressed the relationship among these forces conveniently

in the equation

k(-D)

Where

-N = number ofindividuals inthe population

B- birth andor immigration

S= death andor emigration

wuxitoft3me

k= oa constant

The population size (N) is therefore a convenient inde of the

state of- a popflation at any gvntmThere is atpresent a

number of techniques for estimating this important parameter

Andrewartha (1961) Emlen Stokes andDavis (1949) Olassified

the different ostimation techniques as measurements of absolute

density (diroct measurement) and of relative density (indirect

measurement)y density being defined as the number of animals in ashy

given area Kucheruk (1964) discussed them as indirect direcptan

TABLE OF CONTENTS

INTRODUCTION

REVIEW OF LITERATURE

Trap-mark-recapture method

Quadrat method

Trapline index

Removal technique

Change-in-ratio estimate

Population structural model

Forecasting method

Home ranzo moensiiramont

MATERIALS AND 1THODS

Wet season study

Dry scason study

Radio-tracking

Home range and movements

Populatipn densities

RESULTS AND DISCUSSION

Home ranges and movements

Population densities

Trappability

Capture-rlease-recapbure technique casea

LITERATURE CITED

APPENDIX

Page

1

2

3

7

7

8

9

10

i0

11

14

15

25

17

17

19

19

19

27

32

study 36

41

48

LIST OF TABLES

-Table1 Page

1Movement ofs marked-rats deteed by recapturo method 2-1

lb movoement of radio-monitored rate 26

2a let soason rocapture data 28

2b Dry season recapturc data 28 3ao Monthly wet season densities as estimated

by the Petersen method 29 3b Monthly dry season densities as dete rmined

by different models based on the capture-release-recapture technique 29

4 Dry season population parameters estimated by Jollys stochastic model 32

LIST OF ILLUSTRATIONS

Figure Page

1 Wet 805 -1study area with traps set16

alk- Ydikces 1

2 Dry -esrnstudy gridt 18

3a Apparent home ranges of individlu ly marked rat based upon wet season recapture data 20

3bjApparent home ranges of individually marked rats based upon dry season recapture data 21

4a- Inclusive boundary strip home ranges of six

radio-monitorod rats 23

4b Movoment patetrns of radio-monitored rats 25

5 MontEly population densi ty par hectare 31

6 Distribubion of1 catch amonG t apo aet in g ~ 3

ABSTRACT

Benigno Edwin Abalos University of the Philippines November

1972 Estimating Population Parameters of the Ricefield Rat (Rattus

rattus mindanensis Mearns) Major Professor Pablo S Alfonso

Livetrapping was conducted twice a month for two crop seasons in

a selected rice growing area inSiniloan Laguna Data for the

estimation of population parameters were obtained independently for

eaohseason by moans of the capture release and recapture method

Monthly population density per hectare and subsequent damage to

rice was greater during the wet season In both seasons density

increased toward maturity of the crop Density was negati-ely

corrOlated with the oropcrtion of male0 Li the monthly samples while

nu eignifiant correlation ras found betreen density aad the

proportion o jaeiilos i the 5unple

Juvenilee were more mobile nd xcjibi ed lar-er home ranges than

Itadults adul males and femaes were equally Io tile favesting and X-nprepcartion withovt Lcorpert -n control did not eert immediate

arid Gignifiuant d-ioplacement effect on the population Trap location animal behavior and the prevailing I he

conditions offeted traipablity resulting in vatkbl -rp api bull n even

Within the samIiztxpping perlorl T le prcA m of few reoaptuares1 of mlarked a iwblind te that tine tapC1re release

and ecaptrt Sthrd alone ma b prnctical for AOos Iri

piira4Ion

INTRODUCTION

The study of animal poptilationshas recently received cons erab4 attention Many ttempts have been made to describe the structure of

agiven population quantitatively Consequently more refined

statistical methods have to be evolved to obtain accurate estimates of

the different parameters characteristic of the population

Population parameters in turn provide one of the bases for sound -pest management and maximum utilization of animals of importance to

man Allen (1949) further stressed the need for such parmeters lie

blamed the lack of fast and accurate estimation procedures for the sloW

progress in efficient wildlife management The statement holds

especially true for vertebrate poat management in the Philippines

ViUh ibe iiitantton to curtribute Li th- effort to renedy theo situation

III ootidy Jualutucted at thui Der arrent of ritomo3rgy and Applio-

Zoology and in the rice flelds of Sinloan Lagtuna frcm Scpterabe

971 tn June 1972

The me- of this study reoi1ctiv

1p T cjppkI unctr typical -Vicefiold condltiors of at -shy

-in~esta~ion a ila~b-le echni cjues for ust rig 5oolai Jxat parwietcs

Such 9s opation de saty) oirvival rates bullanoi homeo rnge

2mou Tmltc oiooc are saitte- L1 the 41ud~y of 1ociiz

roden-b pop41~atirnsfishy

2

REVIEW1 OFLITERATURE

populatibn is ever static Itmay attain equilibriui but at

any given time itlis the resul~t of the interaction of three generalized

forces 4ecognized by Davis (1953a)s

Reproduction tends to increase the population mortality tends to decrease itandmovements tend to increase it or decrease it depending upon the net result of immigration and emigration

Lotka (1925) expressed the relationship among these forces conveniently

in the equation

k(-D)

Where

-N = number ofindividuals inthe population

B- birth andor immigration

S= death andor emigration

wuxitoft3me

k= oa constant

The population size (N) is therefore a convenient inde of the

state of- a popflation at any gvntmThere is atpresent a

number of techniques for estimating this important parameter

Andrewartha (1961) Emlen Stokes andDavis (1949) Olassified

the different ostimation techniques as measurements of absolute

density (diroct measurement) and of relative density (indirect

measurement)y density being defined as the number of animals in ashy

given area Kucheruk (1964) discussed them as indirect direcptan

LIST OF TABLES

-Table1 Page

1Movement ofs marked-rats deteed by recapturo method 2-1

lb movoement of radio-monitored rate 26

2a let soason rocapture data 28

2b Dry season recapturc data 28 3ao Monthly wet season densities as estimated

by the Petersen method 29 3b Monthly dry season densities as dete rmined

by different models based on the capture-release-recapture technique 29

4 Dry season population parameters estimated by Jollys stochastic model 32

LIST OF ILLUSTRATIONS

Figure Page

1 Wet 805 -1study area with traps set16

alk- Ydikces 1

2 Dry -esrnstudy gridt 18

3a Apparent home ranges of individlu ly marked rat based upon wet season recapture data 20

3bjApparent home ranges of individually marked rats based upon dry season recapture data 21

4a- Inclusive boundary strip home ranges of six

radio-monitorod rats 23

4b Movoment patetrns of radio-monitored rats 25

5 MontEly population densi ty par hectare 31

6 Distribubion of1 catch amonG t apo aet in g ~ 3

ABSTRACT

Benigno Edwin Abalos University of the Philippines November

1972 Estimating Population Parameters of the Ricefield Rat (Rattus

rattus mindanensis Mearns) Major Professor Pablo S Alfonso

Livetrapping was conducted twice a month for two crop seasons in

a selected rice growing area inSiniloan Laguna Data for the

estimation of population parameters were obtained independently for

eaohseason by moans of the capture release and recapture method

Monthly population density per hectare and subsequent damage to

rice was greater during the wet season In both seasons density

increased toward maturity of the crop Density was negati-ely

corrOlated with the oropcrtion of male0 Li the monthly samples while

nu eignifiant correlation ras found betreen density aad the

proportion o jaeiilos i the 5unple

Juvenilee were more mobile nd xcjibi ed lar-er home ranges than

Itadults adul males and femaes were equally Io tile favesting and X-nprepcartion withovt Lcorpert -n control did not eert immediate

arid Gignifiuant d-ioplacement effect on the population Trap location animal behavior and the prevailing I he

conditions offeted traipablity resulting in vatkbl -rp api bull n even

Within the samIiztxpping perlorl T le prcA m of few reoaptuares1 of mlarked a iwblind te that tine tapC1re release

and ecaptrt Sthrd alone ma b prnctical for AOos Iri

piira4Ion

INTRODUCTION

The study of animal poptilationshas recently received cons erab4 attention Many ttempts have been made to describe the structure of

agiven population quantitatively Consequently more refined

statistical methods have to be evolved to obtain accurate estimates of

the different parameters characteristic of the population

Population parameters in turn provide one of the bases for sound -pest management and maximum utilization of animals of importance to

man Allen (1949) further stressed the need for such parmeters lie

blamed the lack of fast and accurate estimation procedures for the sloW

progress in efficient wildlife management The statement holds

especially true for vertebrate poat management in the Philippines

ViUh ibe iiitantton to curtribute Li th- effort to renedy theo situation

III ootidy Jualutucted at thui Der arrent of ritomo3rgy and Applio-

Zoology and in the rice flelds of Sinloan Lagtuna frcm Scpterabe

971 tn June 1972

The me- of this study reoi1ctiv

1p T cjppkI unctr typical -Vicefiold condltiors of at -shy

-in~esta~ion a ila~b-le echni cjues for ust rig 5oolai Jxat parwietcs

Such 9s opation de saty) oirvival rates bullanoi homeo rnge

2mou Tmltc oiooc are saitte- L1 the 41ud~y of 1ociiz

roden-b pop41~atirnsfishy

2

REVIEW1 OFLITERATURE

populatibn is ever static Itmay attain equilibriui but at

any given time itlis the resul~t of the interaction of three generalized

forces 4ecognized by Davis (1953a)s

Reproduction tends to increase the population mortality tends to decrease itandmovements tend to increase it or decrease it depending upon the net result of immigration and emigration

Lotka (1925) expressed the relationship among these forces conveniently

in the equation

k(-D)

Where

-N = number ofindividuals inthe population

B- birth andor immigration

S= death andor emigration

wuxitoft3me

k= oa constant

The population size (N) is therefore a convenient inde of the

state of- a popflation at any gvntmThere is atpresent a

number of techniques for estimating this important parameter

Andrewartha (1961) Emlen Stokes andDavis (1949) Olassified

the different ostimation techniques as measurements of absolute

density (diroct measurement) and of relative density (indirect

measurement)y density being defined as the number of animals in ashy

given area Kucheruk (1964) discussed them as indirect direcptan

LIST OF ILLUSTRATIONS

Figure Page

1 Wet 805 -1study area with traps set16

alk- Ydikces 1

2 Dry -esrnstudy gridt 18

3a Apparent home ranges of individlu ly marked rat based upon wet season recapture data 20

3bjApparent home ranges of individually marked rats based upon dry season recapture data 21

4a- Inclusive boundary strip home ranges of six

radio-monitorod rats 23

4b Movoment patetrns of radio-monitored rats 25

5 MontEly population densi ty par hectare 31

6 Distribubion of1 catch amonG t apo aet in g ~ 3

ABSTRACT

Benigno Edwin Abalos University of the Philippines November

1972 Estimating Population Parameters of the Ricefield Rat (Rattus

rattus mindanensis Mearns) Major Professor Pablo S Alfonso

Livetrapping was conducted twice a month for two crop seasons in

a selected rice growing area inSiniloan Laguna Data for the

estimation of population parameters were obtained independently for

eaohseason by moans of the capture release and recapture method

Monthly population density per hectare and subsequent damage to

rice was greater during the wet season In both seasons density

increased toward maturity of the crop Density was negati-ely

corrOlated with the oropcrtion of male0 Li the monthly samples while

nu eignifiant correlation ras found betreen density aad the

proportion o jaeiilos i the 5unple

Juvenilee were more mobile nd xcjibi ed lar-er home ranges than

Itadults adul males and femaes were equally Io tile favesting and X-nprepcartion withovt Lcorpert -n control did not eert immediate

arid Gignifiuant d-ioplacement effect on the population Trap location animal behavior and the prevailing I he

conditions offeted traipablity resulting in vatkbl -rp api bull n even

Within the samIiztxpping perlorl T le prcA m of few reoaptuares1 of mlarked a iwblind te that tine tapC1re release

and ecaptrt Sthrd alone ma b prnctical for AOos Iri

piira4Ion

INTRODUCTION

The study of animal poptilationshas recently received cons erab4 attention Many ttempts have been made to describe the structure of

agiven population quantitatively Consequently more refined

statistical methods have to be evolved to obtain accurate estimates of

the different parameters characteristic of the population

Population parameters in turn provide one of the bases for sound -pest management and maximum utilization of animals of importance to

man Allen (1949) further stressed the need for such parmeters lie

blamed the lack of fast and accurate estimation procedures for the sloW

progress in efficient wildlife management The statement holds

especially true for vertebrate poat management in the Philippines

ViUh ibe iiitantton to curtribute Li th- effort to renedy theo situation

III ootidy Jualutucted at thui Der arrent of ritomo3rgy and Applio-

Zoology and in the rice flelds of Sinloan Lagtuna frcm Scpterabe

971 tn June 1972

The me- of this study reoi1ctiv

1p T cjppkI unctr typical -Vicefiold condltiors of at -shy

-in~esta~ion a ila~b-le echni cjues for ust rig 5oolai Jxat parwietcs

Such 9s opation de saty) oirvival rates bullanoi homeo rnge

2mou Tmltc oiooc are saitte- L1 the 41ud~y of 1ociiz

roden-b pop41~atirnsfishy

2

REVIEW1 OFLITERATURE

populatibn is ever static Itmay attain equilibriui but at

any given time itlis the resul~t of the interaction of three generalized

forces 4ecognized by Davis (1953a)s

Reproduction tends to increase the population mortality tends to decrease itandmovements tend to increase it or decrease it depending upon the net result of immigration and emigration

Lotka (1925) expressed the relationship among these forces conveniently

in the equation

k(-D)

Where

-N = number ofindividuals inthe population

B- birth andor immigration

S= death andor emigration

wuxitoft3me

k= oa constant

The population size (N) is therefore a convenient inde of the

state of- a popflation at any gvntmThere is atpresent a

number of techniques for estimating this important parameter

Andrewartha (1961) Emlen Stokes andDavis (1949) Olassified

the different ostimation techniques as measurements of absolute

density (diroct measurement) and of relative density (indirect

measurement)y density being defined as the number of animals in ashy

given area Kucheruk (1964) discussed them as indirect direcptan

ABSTRACT

Benigno Edwin Abalos University of the Philippines November

1972 Estimating Population Parameters of the Ricefield Rat (Rattus

rattus mindanensis Mearns) Major Professor Pablo S Alfonso

Livetrapping was conducted twice a month for two crop seasons in

a selected rice growing area inSiniloan Laguna Data for the

estimation of population parameters were obtained independently for

eaohseason by moans of the capture release and recapture method

Monthly population density per hectare and subsequent damage to

rice was greater during the wet season In both seasons density

increased toward maturity of the crop Density was negati-ely

corrOlated with the oropcrtion of male0 Li the monthly samples while

nu eignifiant correlation ras found betreen density aad the

proportion o jaeiilos i the 5unple

Juvenilee were more mobile nd xcjibi ed lar-er home ranges than

Itadults adul males and femaes were equally Io tile favesting and X-nprepcartion withovt Lcorpert -n control did not eert immediate

arid Gignifiuant d-ioplacement effect on the population Trap location animal behavior and the prevailing I he

conditions offeted traipablity resulting in vatkbl -rp api bull n even

Within the samIiztxpping perlorl T le prcA m of few reoaptuares1 of mlarked a iwblind te that tine tapC1re release

and ecaptrt Sthrd alone ma b prnctical for AOos Iri

piira4Ion

INTRODUCTION

The study of animal poptilationshas recently received cons erab4 attention Many ttempts have been made to describe the structure of

agiven population quantitatively Consequently more refined

statistical methods have to be evolved to obtain accurate estimates of

the different parameters characteristic of the population

Population parameters in turn provide one of the bases for sound -pest management and maximum utilization of animals of importance to

man Allen (1949) further stressed the need for such parmeters lie

blamed the lack of fast and accurate estimation procedures for the sloW

progress in efficient wildlife management The statement holds

especially true for vertebrate poat management in the Philippines

ViUh ibe iiitantton to curtribute Li th- effort to renedy theo situation

III ootidy Jualutucted at thui Der arrent of ritomo3rgy and Applio-

Zoology and in the rice flelds of Sinloan Lagtuna frcm Scpterabe

971 tn June 1972

The me- of this study reoi1ctiv

1p T cjppkI unctr typical -Vicefiold condltiors of at -shy

-in~esta~ion a ila~b-le echni cjues for ust rig 5oolai Jxat parwietcs

Such 9s opation de saty) oirvival rates bullanoi homeo rnge

2mou Tmltc oiooc are saitte- L1 the 41ud~y of 1ociiz

roden-b pop41~atirnsfishy

2

REVIEW1 OFLITERATURE

populatibn is ever static Itmay attain equilibriui but at

any given time itlis the resul~t of the interaction of three generalized

forces 4ecognized by Davis (1953a)s

Reproduction tends to increase the population mortality tends to decrease itandmovements tend to increase it or decrease it depending upon the net result of immigration and emigration

Lotka (1925) expressed the relationship among these forces conveniently

in the equation

k(-D)

Where

-N = number ofindividuals inthe population

B- birth andor immigration

S= death andor emigration

wuxitoft3me

k= oa constant

The population size (N) is therefore a convenient inde of the

state of- a popflation at any gvntmThere is atpresent a

number of techniques for estimating this important parameter

Andrewartha (1961) Emlen Stokes andDavis (1949) Olassified

the different ostimation techniques as measurements of absolute

density (diroct measurement) and of relative density (indirect

measurement)y density being defined as the number of animals in ashy

given area Kucheruk (1964) discussed them as indirect direcptan

INTRODUCTION

The study of animal poptilationshas recently received cons erab4 attention Many ttempts have been made to describe the structure of

agiven population quantitatively Consequently more refined

statistical methods have to be evolved to obtain accurate estimates of

the different parameters characteristic of the population

Population parameters in turn provide one of the bases for sound -pest management and maximum utilization of animals of importance to

man Allen (1949) further stressed the need for such parmeters lie

blamed the lack of fast and accurate estimation procedures for the sloW

progress in efficient wildlife management The statement holds

especially true for vertebrate poat management in the Philippines

ViUh ibe iiitantton to curtribute Li th- effort to renedy theo situation

III ootidy Jualutucted at thui Der arrent of ritomo3rgy and Applio-

Zoology and in the rice flelds of Sinloan Lagtuna frcm Scpterabe

971 tn June 1972

The me- of this study reoi1ctiv

1p T cjppkI unctr typical -Vicefiold condltiors of at -shy

-in~esta~ion a ila~b-le echni cjues for ust rig 5oolai Jxat parwietcs

Such 9s opation de saty) oirvival rates bullanoi homeo rnge

2mou Tmltc oiooc are saitte- L1 the 41ud~y of 1ociiz

roden-b pop41~atirnsfishy

2

REVIEW1 OFLITERATURE

populatibn is ever static Itmay attain equilibriui but at

any given time itlis the resul~t of the interaction of three generalized

forces 4ecognized by Davis (1953a)s

Reproduction tends to increase the population mortality tends to decrease itandmovements tend to increase it or decrease it depending upon the net result of immigration and emigration

Lotka (1925) expressed the relationship among these forces conveniently

in the equation

k(-D)

Where

-N = number ofindividuals inthe population

B- birth andor immigration

S= death andor emigration

wuxitoft3me

k= oa constant

The population size (N) is therefore a convenient inde of the

state of- a popflation at any gvntmThere is atpresent a

number of techniques for estimating this important parameter

Andrewartha (1961) Emlen Stokes andDavis (1949) Olassified

the different ostimation techniques as measurements of absolute

density (diroct measurement) and of relative density (indirect

measurement)y density being defined as the number of animals in ashy

given area Kucheruk (1964) discussed them as indirect direcptan

2

REVIEW1 OFLITERATURE

populatibn is ever static Itmay attain equilibriui but at

any given time itlis the resul~t of the interaction of three generalized

forces 4ecognized by Davis (1953a)s

Reproduction tends to increase the population mortality tends to decrease itandmovements tend to increase it or decrease it depending upon the net result of immigration and emigration

Lotka (1925) expressed the relationship among these forces conveniently

in the equation

k(-D)

Where

-N = number ofindividuals inthe population

B- birth andor immigration

S= death andor emigration

wuxitoft3me

k= oa constant

The population size (N) is therefore a convenient inde of the

state of- a popflation at any gvntmThere is atpresent a

number of techniques for estimating this important parameter

Andrewartha (1961) Emlen Stokes andDavis (1949) Olassified

the different ostimation techniques as measurements of absolute

density (diroct measurement) and of relative density (indirect

measurement)y density being defined as the number of animals in ashy

given area Kucheruk (1964) discussed them as indirect direcptan

3

Gtirreabslut cesus (167)fuxtOr grouped them into total countincompete count indirect count and markingmethods

-omplete enumeration utilizes the whole population an ths1give

absolute counts This includes methods such as exhaustive trappig -with return of marked animals to the field visual counting on measured

areass and systematic killing with an enumerationof the animals as

they are removed In this type of census each member of the population has to be counted without confusion duplication or omission The problem ismagnified whenever a large population is

under study and there are only a few enumerators This approach therefore althaugh direct and desirable usually is expensive and

time consuming

Incompleteenumeration isresorted to when only a part of the whole population can be seen or enumerated at any one time This has

the advantage over the total count when one is dealing with mobile

populations ranging over extensive areas Included in this grouping

are the quadrat methodp strip censuses roadside counts flushing counts and other sampling techniques

Indirect countson the other hand ars based on signs or indices of abundance sunh jqa 4-Iplusmns dropjpings nests and amount of food consumed rather than actual numbers These indices are useful in the study of timid or nocturnal animals but it may be difficult to compare the signs from one Per4od to another unless naturalvarIoati i

are considered

Trap-mark-reture metod This method is variusly alled as mark release and recapture method multi recapture census captureshyrecapture and the like Andrewartha(1961) considered it as a measure

of absolute density while Emlen etal (J99) grouped itudrindirect

masurement yielding relative data Some models under this group

likewise provide estimates of- survival an dilution rates which ar in

effect similar to birth and death rates

-This techiu ifat bcoming polr amngbiologists ee6

(1965) believed that Dail was the first to use- it in estimating

ipopuilation density i 1917 He stated that Petersen one of its main

foundersti used it only in estimating mortality rates in 1889 The

LincoInindex still used by mammalogists was first used to calculate

waterfowl abundance in 1930 Since then several refinements and added

features have been made on this technique

Jackson- (139 1940 1944 1948)-developed his deterministic

model to estimate tse-tso fly populations when every individualin the

population was assumed to be subjected to the same survival rate

Fisher and Ford (1947) used this method in studying the spread of a

gene ina moth colony Baley (1951P 1952 refined Jacksons methods

and improved the interpretation of recapture data Darroch (1958 1959)

gave estimates for a cI6Psedpopuation and for a population where there

isimmigration 6r death He also provided a two-sample censuswhen

tagging and sampling are stratified (161) Cormack (1964p 1966)

developed estimates for a nonrandom sample of fulmar petrels and a test

for equal catchability ofmnrkodand unmarked animals Seber (1962

1965)t considered the case when marked individuals cannotb recaptured

more than onc3 As in hunting and- fishing He also provided a test for

equi-catchability in-a closed population

JoJly(1963o 1965)developed his deterministic and stochastlo

models with maximum ikelihood equations estimates ofnumbers

survival and dilution rated with corresponding variances and covariances

Manly and Parr (1968) and later iManly (1969) aiso developedestimating

equations using rlcapture deta but these were reducible to Jolly S

Cormack (i971) cited alternative estimates when the standard

assoptions of the Jolly-Sober models do not occur Janion e (1968)

likewise suggested estimates of numbers of rodents with variable

probabiiity of capture Eberhardt (1969) suggested a modified method

for estimating density based on the assumption that recaptures follow

the geometric grequency distribution

Theefficiency of the technique is largely dependent on h6 well

the animals are marked before they are released into t eoppulation

Techniques of efficient marking of the animals and thair uses in

andecological studies ar iven by WooaburY (1956) Taber (1956)

Pendleton$1956) bull

The basic principle of the trap-mark-recapture method is rather

simple The population is first sampled Each animal caught is assigned a uniquenumber or marking code before it is released into

the population Later another sample is taken and the ratio between

the number of markedtand unmarked animals provides the estimates of

the population density given by the equation

NM

Where o

P populat ion density

IN= number of individuals captured including those recaptured

R =Rtaggedindividuale recaptured

N ~nmbe o tged individuals released into teppulation

The Procedure is generally~reppated over a period of time Every

unmarked individual is given a uniqu4e marked on itsIfirst capture

Recapturesare then recorded under appropriate dates without further

markings

Theproision ofthe estimates howeve are dependent on certain

assumptions which usually include

1 The marked animals distribute thomselveo uniformly with

unmarked individuals and

2 The marked ones re caught at thesame rateas the unmarked

Ones -

Andrevrhta- (1961) cited two tochnicaldifficalties encountez ed

inthis ziethod-A anely

hendegtraps art d spei~ty in an area that is not limited by sharp ecological boundaries difficalties arise with respect to the placing oftraps reltive to the boundaries of the area

2 It is difficult to attribute a precise variance to the -wtimatoa that are given by this method because the

-calculations are tediouD and difficult

Benigno (1969) 1 prepared a program (FORTRAN II) of the more

genera an iey applicable stochastic model of Joll (-1965 o

facilitate the calculations of the estimates and their variancs

EE Benigno Capture release and recapture technique programming and application (Unpublished undergraduate thesisUniversiftv of thn P 1 ninn 10QIQ

7

adrat method In this method small areas are chosen at random

from the area which contains the whole population Complete counts of the animals in thedsmaller-areas aro thentaken to estimate the total

number in the larger area It isa plie that the smaller areas are

of known sizes relative to the whole area One difficulty with this

ethod is that some animals have the tendency to escape the observer

hThe reliability of the estimates by this method therefore depends on

how representative the quadrats are to thewhole area and how muchon

of the actual numbers in the quadrats are observed This method is

likewise greatly affected by aggregation Gutierrez (1967) cited the

quadrat method as used nthe study of fishes birds and mammals

Bole (1939) and Pelikan et al (1969) also worked on this methoCL

Trapline indej Thia ita also known as trap-night index or simply trapping success is a simple measure of relative abundance

With this method a number of traps are usually set for three

consecutive nights and the trapping success is then taken as the

ratio of the total catch to the total effective trap-nights Formozov

and Isakov (1967) expressed the index in terms of 100 trap-nights

Southern (1965) dicusased the use of this method in tracking broad

changes of distribution in time and space of small rodent populations

Although the procedure is simpler than the other techniques its

reliability has been questioned by various workers Stickel (1948)

concluded that the trapline is not fully reliable due to differences

inindividual ranges and habitat factors Tanaka (1960) found

evidences against the method but stated that the density esimated by

this method bUareliable if the probability of capture reman

constant Kucheruk (1964) recommended the standardization of the

techniques of spacing traplinds in order to obtain comparable results

Hansson (1967) noted that the relation between the index and population

density differed with species

RemOvl technique This is im irto thetwo methods mentioned

(i939) and Davia (1964)ldescribed completeearlier Leslie and dvisshy

(1955) Chose selective-removal to yield absoldtedensity Ohapman

removal to effect chango in population composition while Cahalane (194l)

used trap-removal census Grodzinski etal (1966) suggested the use

Zippin (1956) describedof regression estimates with this method

and evaluated the use of this method in estimating animal populations

This tochnique assumes a stationary population during the trappixg

program Likdthe othertoohniques it also assumes a uniform and

constant probabi1ity of iwe from one trapping to another for a

given period Population size is then estimated by regression method

as

(3)E(y)=Nx)p

Whe)we

p the probability of cqtietQ rig aingle period of trapping

N the original population size shy

i the number of animals caught prior to the ith period

slope of the line estimates the probabilityTheabsolute value of the

of oaptuze and t hbor-inter cept estim~ates the population size

9 Determinationof the precision of the estimates as well as the appropriate sample size are givenby Zippin(1956)

hange-in-ratiQoestimate Kelker (1940 1943) used exratio equations for determining wildlife populations Chapman and Robson

(1960) analyzed the catch curve with respect to age distributions They stated that the catch curve from a stationary population based on the assumption that age distribution is geometric They gavo the annual

survival rate as z(i + - 1) I being the mean age of sample size -n Hanson (1963) calcQulated productivity survival and abundance of some vertebrates based on seX and age ratios

Rupp (1966) stated that the estimates based on changes inrelative abundance (change-inratio) of two classes of individuals in the population can be presented in one basic estimating equation namqIy

M_- p(M J Fy 7T(MJ

P2 P1 (4)

Where

N1 the totalnumber of animalsin thepopulation at

time 1(T) pi the decimal fraction -of population N whiCh consists of

one kind (Males8 for cicnple)

p2 new decimal fraction (of males) among N2 individualal 2N

X=number of males added or removed Tbetween and

F =number of femalos added or removed between T1 and Tshy

Where o

P populat ion density

IN= number of individuals captured including those recaptured

R =Rtaggedindividuale recaptured

N ~nmbe o tged individuals released into teppulation

The Procedure is generally~reppated over a period of time Every

unmarked individual is given a uniqu4e marked on itsIfirst capture

Recapturesare then recorded under appropriate dates without further

markings

Theproision ofthe estimates howeve are dependent on certain

assumptions which usually include

1 The marked animals distribute thomselveo uniformly with

unmarked individuals and

2 The marked ones re caught at thesame rateas the unmarked

Ones -

Andrevrhta- (1961) cited two tochnicaldifficalties encountez ed

inthis ziethod-A anely

hendegtraps art d spei~ty in an area that is not limited by sharp ecological boundaries difficalties arise with respect to the placing oftraps reltive to the boundaries of the area

2 It is difficult to attribute a precise variance to the -wtimatoa that are given by this method because the

-calculations are tediouD and difficult

Benigno (1969) 1 prepared a program (FORTRAN II) of the more

genera an iey applicable stochastic model of Joll (-1965 o

facilitate the calculations of the estimates and their variancs

EE Benigno Capture release and recapture technique programming and application (Unpublished undergraduate thesisUniversiftv of thn P 1 ninn 10QIQ

7

adrat method In this method small areas are chosen at random

from the area which contains the whole population Complete counts of the animals in thedsmaller-areas aro thentaken to estimate the total

number in the larger area It isa plie that the smaller areas are

of known sizes relative to the whole area One difficulty with this

ethod is that some animals have the tendency to escape the observer

hThe reliability of the estimates by this method therefore depends on

how representative the quadrats are to thewhole area and how muchon

of the actual numbers in the quadrats are observed This method is

likewise greatly affected by aggregation Gutierrez (1967) cited the

quadrat method as used nthe study of fishes birds and mammals

Bole (1939) and Pelikan et al (1969) also worked on this methoCL

Trapline indej Thia ita also known as trap-night index or simply trapping success is a simple measure of relative abundance

With this method a number of traps are usually set for three

consecutive nights and the trapping success is then taken as the

ratio of the total catch to the total effective trap-nights Formozov

and Isakov (1967) expressed the index in terms of 100 trap-nights

Southern (1965) dicusased the use of this method in tracking broad

changes of distribution in time and space of small rodent populations

Although the procedure is simpler than the other techniques its

reliability has been questioned by various workers Stickel (1948)

concluded that the trapline is not fully reliable due to differences

inindividual ranges and habitat factors Tanaka (1960) found

evidences against the method but stated that the density esimated by

this method bUareliable if the probability of capture reman

constant Kucheruk (1964) recommended the standardization of the

techniques of spacing traplinds in order to obtain comparable results

Hansson (1967) noted that the relation between the index and population

density differed with species

RemOvl technique This is im irto thetwo methods mentioned

(i939) and Davia (1964)ldescribed completeearlier Leslie and dvisshy

(1955) Chose selective-removal to yield absoldtedensity Ohapman

removal to effect chango in population composition while Cahalane (194l)

used trap-removal census Grodzinski etal (1966) suggested the use

Zippin (1956) describedof regression estimates with this method

and evaluated the use of this method in estimating animal populations

This tochnique assumes a stationary population during the trappixg

program Likdthe othertoohniques it also assumes a uniform and

constant probabi1ity of iwe from one trapping to another for a

given period Population size is then estimated by regression method

as

(3)E(y)=Nx)p

Whe)we

p the probability of cqtietQ rig aingle period of trapping

N the original population size shy

i the number of animals caught prior to the ith period

slope of the line estimates the probabilityTheabsolute value of the

of oaptuze and t hbor-inter cept estim~ates the population size

9 Determinationof the precision of the estimates as well as the appropriate sample size are givenby Zippin(1956)

hange-in-ratiQoestimate Kelker (1940 1943) used exratio equations for determining wildlife populations Chapman and Robson

(1960) analyzed the catch curve with respect to age distributions They stated that the catch curve from a stationary population based on the assumption that age distribution is geometric They gavo the annual

survival rate as z(i + - 1) I being the mean age of sample size -n Hanson (1963) calcQulated productivity survival and abundance of some vertebrates based on seX and age ratios

Rupp (1966) stated that the estimates based on changes inrelative abundance (change-inratio) of two classes of individuals in the population can be presented in one basic estimating equation namqIy

M_- p(M J Fy 7T(MJ

P2 P1 (4)

Where

N1 the totalnumber of animalsin thepopulation at

time 1(T) pi the decimal fraction -of population N whiCh consists of

one kind (Males8 for cicnple)

p2 new decimal fraction (of males) among N2 individualal 2N

X=number of males added or removed Tbetween and

F =number of femalos added or removed between T1 and Tshy

7

adrat method In this method small areas are chosen at random

from the area which contains the whole population Complete counts of the animals in thedsmaller-areas aro thentaken to estimate the total

number in the larger area It isa plie that the smaller areas are

of known sizes relative to the whole area One difficulty with this

ethod is that some animals have the tendency to escape the observer

hThe reliability of the estimates by this method therefore depends on

how representative the quadrats are to thewhole area and how muchon

of the actual numbers in the quadrats are observed This method is

likewise greatly affected by aggregation Gutierrez (1967) cited the

quadrat method as used nthe study of fishes birds and mammals

Bole (1939) and Pelikan et al (1969) also worked on this methoCL

Trapline indej Thia ita also known as trap-night index or simply trapping success is a simple measure of relative abundance

With this method a number of traps are usually set for three

consecutive nights and the trapping success is then taken as the

ratio of the total catch to the total effective trap-nights Formozov

and Isakov (1967) expressed the index in terms of 100 trap-nights

Southern (1965) dicusased the use of this method in tracking broad

changes of distribution in time and space of small rodent populations

Although the procedure is simpler than the other techniques its

reliability has been questioned by various workers Stickel (1948)

concluded that the trapline is not fully reliable due to differences

inindividual ranges and habitat factors Tanaka (1960) found

evidences against the method but stated that the density esimated by

this method bUareliable if the probability of capture reman

constant Kucheruk (1964) recommended the standardization of the

techniques of spacing traplinds in order to obtain comparable results

Hansson (1967) noted that the relation between the index and population

density differed with species

RemOvl technique This is im irto thetwo methods mentioned

(i939) and Davia (1964)ldescribed completeearlier Leslie and dvisshy

(1955) Chose selective-removal to yield absoldtedensity Ohapman

removal to effect chango in population composition while Cahalane (194l)

used trap-removal census Grodzinski etal (1966) suggested the use

Zippin (1956) describedof regression estimates with this method

and evaluated the use of this method in estimating animal populations

This tochnique assumes a stationary population during the trappixg

program Likdthe othertoohniques it also assumes a uniform and

constant probabi1ity of iwe from one trapping to another for a

given period Population size is then estimated by regression method

as

(3)E(y)=Nx)p

Whe)we

p the probability of cqtietQ rig aingle period of trapping

N the original population size shy

i the number of animals caught prior to the ith period

slope of the line estimates the probabilityTheabsolute value of the

of oaptuze and t hbor-inter cept estim~ates the population size

9 Determinationof the precision of the estimates as well as the appropriate sample size are givenby Zippin(1956)

hange-in-ratiQoestimate Kelker (1940 1943) used exratio equations for determining wildlife populations Chapman and Robson

(1960) analyzed the catch curve with respect to age distributions They stated that the catch curve from a stationary population based on the assumption that age distribution is geometric They gavo the annual

survival rate as z(i + - 1) I being the mean age of sample size -n Hanson (1963) calcQulated productivity survival and abundance of some vertebrates based on seX and age ratios

Rupp (1966) stated that the estimates based on changes inrelative abundance (change-inratio) of two classes of individuals in the population can be presented in one basic estimating equation namqIy

M_- p(M J Fy 7T(MJ

P2 P1 (4)

Where

N1 the totalnumber of animalsin thepopulation at

time 1(T) pi the decimal fraction -of population N whiCh consists of

one kind (Males8 for cicnple)

p2 new decimal fraction (of males) among N2 individualal 2N

X=number of males added or removed Tbetween and

F =number of femalos added or removed between T1 and Tshy

this method bUareliable if the probability of capture reman

constant Kucheruk (1964) recommended the standardization of the

techniques of spacing traplinds in order to obtain comparable results

Hansson (1967) noted that the relation between the index and population

density differed with species

RemOvl technique This is im irto thetwo methods mentioned

(i939) and Davia (1964)ldescribed completeearlier Leslie and dvisshy

(1955) Chose selective-removal to yield absoldtedensity Ohapman

removal to effect chango in population composition while Cahalane (194l)

used trap-removal census Grodzinski etal (1966) suggested the use

Zippin (1956) describedof regression estimates with this method

and evaluated the use of this method in estimating animal populations

This tochnique assumes a stationary population during the trappixg

program Likdthe othertoohniques it also assumes a uniform and

constant probabi1ity of iwe from one trapping to another for a

given period Population size is then estimated by regression method

as

(3)E(y)=Nx)p

Whe)we

p the probability of cqtietQ rig aingle period of trapping

N the original population size shy

i the number of animals caught prior to the ith period

slope of the line estimates the probabilityTheabsolute value of the

of oaptuze and t hbor-inter cept estim~ates the population size

9 Determinationof the precision of the estimates as well as the appropriate sample size are givenby Zippin(1956)

hange-in-ratiQoestimate Kelker (1940 1943) used exratio equations for determining wildlife populations Chapman and Robson

(1960) analyzed the catch curve with respect to age distributions They stated that the catch curve from a stationary population based on the assumption that age distribution is geometric They gavo the annual

survival rate as z(i + - 1) I being the mean age of sample size -n Hanson (1963) calcQulated productivity survival and abundance of some vertebrates based on seX and age ratios

Rupp (1966) stated that the estimates based on changes inrelative abundance (change-inratio) of two classes of individuals in the population can be presented in one basic estimating equation namqIy

M_- p(M J Fy 7T(MJ

P2 P1 (4)

Where

N1 the totalnumber of animalsin thepopulation at

time 1(T) pi the decimal fraction -of population N whiCh consists of

one kind (Males8 for cicnple)

p2 new decimal fraction (of males) among N2 individualal 2N

X=number of males added or removed Tbetween and

F =number of femalos added or removed between T1 and Tshy

9 Determinationof the precision of the estimates as well as the appropriate sample size are givenby Zippin(1956)

hange-in-ratiQoestimate Kelker (1940 1943) used exratio equations for determining wildlife populations Chapman and Robson

(1960) analyzed the catch curve with respect to age distributions They stated that the catch curve from a stationary population based on the assumption that age distribution is geometric They gavo the annual

survival rate as z(i + - 1) I being the mean age of sample size -n Hanson (1963) calcQulated productivity survival and abundance of some vertebrates based on seX and age ratios

Rupp (1966) stated that the estimates based on changes inrelative abundance (change-inratio) of two classes of individuals in the population can be presented in one basic estimating equation namqIy

M_- p(M J Fy 7T(MJ

P2 P1 (4)

Where

N1 the totalnumber of animalsin thepopulation at

time 1(T) pi the decimal fraction -of population N whiCh consists of

one kind (Males8 for cicnple)

p2 new decimal fraction (of males) among N2 individualal 2N

X=number of males added or removed Tbetween and

F =number of femalos added or removed between T1 and Tshy

InamorereCnt work Paulfc andRobson (1969) suggested a general

unified approach for estimating abundance productivity and exploitation rates from observed changes in population composition whether natural

or artificially constructed They provided plans for experiments and

surveys and also charts for determining sample size required to

estimate the population size within a given percent error Likewise

they showed that the multiple-mark-recapture analysis is a form of a

change-in-ratio estimate

The change-in-ratio estimate may be used when a population can

be Classified into two categories and a change occurs in the relative

abundance in the two types of animals

o olation structural model Population density and other

parameters may also be obtained from the population structure Blair

(1951) Leslie Venabloo and Venables (1952) Anderson (1961) and

Davenport (1964) studied the tx-ucture of some rodents under certain

condiLions Tanaka (1951) obsetrvod considerable yearly change in

population sLzo and structure but nirj not gIve the cbb-acter anl

cause of bhe population ehift Smirnov (1967) and Reimy Overtct

and Wight (1970) gave estimates of parameters based on the anaysis of

struut=-il jacdeAS

s4 g me od Every population har its irnat capacity for

iucoase iu numer y rndrWa ieta Birciynd(1954) suggcsth this

ca~paciby ba cinoterl by tiLnd defineo by

R Lorn 0~ (5)

Where

rm = innate capacity for increase in numbers calcuatd from experimentaldata and relating to a population with a

stable age distribution n=nbor of times a population will multiply per generation

(net reproductive rate)

T = generation time

Realizing the importance of this new population statistic Laughlin (1965) proposed a simple appro-cimation of equation (5)

r Loge RT (6) C

Where

V = Cohort generation time wLich is also equal to the mean age of mothers in cohort at birth of a female offspring

The an~log givese r c ihe nwaber of tiien a population multiplies

ReeIf perunit time 1dvanced techniques for forecaaig the nambers of some

populZations have been rpoposed by Scindv-ur (199) 3cov 96l Shkev(1963) andMaksimoir C196)

Home ane meas2emnnt Burt L90 1at the concepts of taraoitorLility and home rangu wore applicable tu 6mmal popuIationa He tined home rnge asc thot area trvesed by the ividoa in to normal act vitis of food gathering ming a -

Where

rm = innate capacity for increase in numbers calcuatd from experimentaldata and relating to a population with a

stable age distribution n=nbor of times a population will multiply per generation

(net reproductive rate)

T = generation time

Realizing the importance of this new population statistic Laughlin (1965) proposed a simple appro-cimation of equation (5)

r Loge RT (6) C

Where

V = Cohort generation time wLich is also equal to the mean age of mothers in cohort at birth of a female offspring

The an~log givese r c ihe nwaber of tiien a population multiplies

ReeIf perunit time 1dvanced techniques for forecaaig the nambers of some

populZations have been rpoposed by Scindv-ur (199) 3cov 96l Shkev(1963) andMaksimoir C196)

Home ane meas2emnnt Burt L90 1at the concepts of taraoitorLility and home rangu wore applicable tu 6mmal popuIationa He tined home rnge asc thot area trvesed by the ividoa in to normal act vitis of food gathering ming a -

caring for the young -Jorgenson 01968) stated that homerange may also

measure probable intsmall mammals Sticke (1964) provided

a means of utilizing the home range information to estimate density

The iestimation of this useful parameter has been studied from

synthetic recaptures or simulated trapping of artificial populations

by Davis (1953b) and Stickel (1954) Davis (1953b) found that

recaptures were not normally distributed but the frequency distribution

of distances between captures was approximately normal and showed that

there were few chances of recaptures at short distances He

recommended that the number of recaptures at particular distances be

divided by the number of chances of recaptures at those distances

Stickel (1954) stated that range size increased with succossive

captures ntil a level was reached which approimate-d the true range

He further re=aled thet fewer captures were requized whon traps wore

far apart then wlhen thoy vroo oloes togetier Ietzga0 and Hill (1971)

compared the araount of observed overlap of a given set of home ranges

against the epected overlap if those ranges were randomly distributrd

wthin the hlbitat They aluo devised a computur progr-m to determine

the expected -everap of a set of home rangos Home range may be analyzed from recapture data (Davis 1953b)

tracks on smoked karyograph pa-per (Justice L61) and by mean- of

telemetry (Tester rnd Sniff 1965) The first apjacO IV t ho same

as tho capture-relase-rencat-rePihnhd The only diff erne Js that

the distances between recapturelo of orked aidmas e also measured

13

Traps are usually arranged in rectangular grid Davis (1953b ) stated the disadvantages of the grid system asr

1 The animalls home range does not necessarily coincide with the distribution of the traps the home range may extend beyond the grid or the traps inwhich the animal was caught and that the home range can not be calculated for animals caught in traps that are in straight line

2 Great labor in laying out the grid itself the necessity of setting some traps in obviously unfavorable locations and the need to recapture a single individual many times (about 15-20 times) to obtain

adequate data

3 Little idea of the intensity of use of the various parts of

the home range is gained

Estimation techniques using recapture data include recording movement data in terms of frequency of maximum distance between

recaptttres (Evans and Holdenreid 1913) distancef of recaptures

(Davist Mien and Stokes 1948) miniumi method (Dalkje 1942 l4ohr

1947) and boundary strip method by Blair (1940)

The second approach makes use of smoked karyograph paper instead

of traps in detecting home ranges of individually too-jmarcod rats

The smoked paper placed in unbaited cartons are also arranged in rectangular grid Justice (19b) stated that with this iothod as

many as ton records can be obtained from an individual n a single nighb- the biases of trap inhibition learning and trap fatig inheeAntin the macikand-recapt o method can be avoided and

information suitable forinvestigation of the theoretical probability

density functions of anbmA3activity can be f ond

Difficuties encountered in the study of home range as stated

by Davis (1953b)are 1i Animals do not travel in straight lines between capturs

2 Animalsmay Jlean to go into- traps for food andhence give

too many short distances

3 Traps may not be suitably spaced to indicate maximum

Smovements

4 Transients are included

5 The data give only an index of home range

Stickel (1954) compared some methods and found the so-called

exclusive boundary strip method the mostas accurate In this method

rectangles are constructed the extertial points of capture are

considered centers of the rectanqles the sides of which equal the

distances between traps and bhe corners are so connected su as to

enclose the less area

M4TERAIJS ANRD IMTNODS

By means ofntubered stakes the study areas wera set up in

selected r c fieldsin Siniloan Laguna or--k in these areas

focused on the study vf rat moveOment size n3 fshape of nomui rangeshy

density and srvival rates badod on the captirereleasj-rccap6ire

mathod Prevailul farm pract cIc and we tber ondi Lions were

recorded

Wet season The study area (Figure)- onsisted of si rectangular

paddies totalling about 5400 sq m It was bounded on the northern

side by S~irius grossus grasses on the east by aimarshy area and

shorter grasses mostly Cyperus imbricatus and C compactu on the

south and west by rice fields The eastern half of the field was

Usually left uncultivated during the season as itwas often deeply

flooded The other half was also submerged almost throughout the yeari

In this study area 50 locally made live traps (17 x 28 x 13 cm

were cages) were set 10 meters apart along the dikes The live traps

were baitcd with coconut in the afternoon and inspected early the

net morning Live trapping was done every other week each trapping

period lasting three nights This portion of the study lasted six

months to include the entire wet season crop and the land preparation

and transplanting of thn ne-t ran

rytpeson During the dry season more fields incluling the

previouysl marshy areas were cultivated and planted to rice of the

04 variet A bigger (approrimat-zly 16900 sq m) and more uniform

area (Figure 2) adjacent to thi wet season plot vampO solected for the

rest of the study

A total of 196 collapsiblo live traps wore set 101meters apar

near numbered staice -rrarged in a permanent grid inside the paddies

Traps were baed with sweet potato late in the aiternofn d

inspected carly th4 ieoJt morniiig Trapping s alar dutneevery othoeshy

16

FGRASSES lin

UNCULTIVATED RICE FMlLPD

CULT ATED KELMi RIC

trapplite

1 wet seasipr Study Figurearea with traps Eet along paddy dies

week tocover the following stages of the dry season rico crop 4 weeks after transplanting (WAT) 8 WAT 12 WAT and 1 week after harvest

Each trapping period lasted three nights

In both seasonsy every rat was marked on its first capture by earpunching or-by numbered aluminum ear tags After determiningthe

sex weight reproductive condition and visible parasitism the -

numbered rat in good condition was released at the site of capture

S3ite of first capture and subsequent recaptures were noted During the last trapping period snap traps were set at 15-meter

interval for three consecutive nights around the grid in an attempt to recover marked rats that may have emigrated or shifted home range up

to 75 meters from the cides of the grid

Radio-trackin Radio-tracking uas done a week before harvest of the dry season crop to supplement the recapture data Only seven rats caught at least 10 metpoa +k- deg3Ao ie W- azawere fitted i 4 Wniature transistorized radio transmitters The rats were

monitored at least once every six boar from time of ralease until no further contects could bc made The dlke along line 6 of the grid

served as the reading dike (Figure 2) Most of the points were taken

simultaneously by two radio receivers stationed near points 6-1 and

6-4 The ttap sito in the grid also servod as reference points forW

the approCiniae locations of the rats

Homern andFes ftvemgrts Th distanceLtravoled by a markd or

radio-monitored nh ortc~ - nt was measu ed by baking thesh e distanceiat tuice l -

-18

14

12

SAE S RE M 3

Fiur 2Dr---64 ~ ok s dd S d

19

between two sa esiocontact points saon The distance 6xom

release point was taken int a similar manner Shapo andsize o home range was detormined by the inclusive

boundary strip method (Blair 1940) Boundary strips equal in wIdth thalf tho disatance between traps (f ive meters) were laid off around

the minimum area wherein the rat was locatod The home range was then

dividodinto smaller rectangles and triangles of known dimensions the sumof the smaller areas being equal to the area of the home rangebull

Popuiation densities Population densities were estimated by

models based on capture-releaso-recapture method yhose requirements

were met by the data For thewet season data unly the Petersen model as used by Bailey (192) a- applied For the dry season data

Raynes (1949) graphical model as well as Jollys (0965) abochastic model were also used Tn (1bo eiape apply Jollys (965) stochastic

model the Marchand April datawere combined and the recaoture in

June was excludedasit was made outsido the study grid Marked

arimals 6 ptured Ind recaptured within the same month and animal that

eScaped untagei were ec Ided from tecomputations rPcucatio

densities per hectare werebased on the numbr ofrats inthe

effective census areas as defined by MacTulich (1951)

IIESUIjrSLU~D DISC IOU

l~ igares3a and 3b sihow nAe apparent

s i d lnom-Ir of vlytvn -v marked rats based upon recapturo data

20

777 7 77 77 X7

7 77 7 77

74 77~7 9 V

7 c~ 7 17 7 7

77 1Om~ 7

7 _______ 7

7 7 7

- 7 7 7 7 7 7 7

7 S b 7 7 7 7 7

7 7 7

7 7 7 7 7

~ I7~~~ 7777 7 j777

J~ 7 7 7

7 __ 7

7 77 77 I

7 77

7 7 shy7 71 777I- 1 7

717 77

7 7 -

7 77 77~ 7

7 7 j 7 ~ 7 7

77 I 7 7I

1 77

77 77 77 77 7~~7 7 7~7 77 77

7177 7 7 77 7

7 7 77

7 77 7 77

7~j

7777777 j77 77 7~ 7 77 77~ 7 ~ 777 7U7~77A~I7~7U77777i77 ~ ~ ~ 7

77 777 77

7Ftgure 3a -Appare~2t home range~I of md vhiuaJiy rnazlced9za 7 ba~ed

7 7 - U~Ofl Wet season recaptUXe datampL 77 77 77 7

13

Traps are usually arranged in rectangular grid Davis (1953b ) stated the disadvantages of the grid system asr

1 The animalls home range does not necessarily coincide with the distribution of the traps the home range may extend beyond the grid or the traps inwhich the animal was caught and that the home range can not be calculated for animals caught in traps that are in straight line

2 Great labor in laying out the grid itself the necessity of setting some traps in obviously unfavorable locations and the need to recapture a single individual many times (about 15-20 times) to obtain

adequate data

3 Little idea of the intensity of use of the various parts of

the home range is gained

Estimation techniques using recapture data include recording movement data in terms of frequency of maximum distance between

recaptttres (Evans and Holdenreid 1913) distancef of recaptures

(Davist Mien and Stokes 1948) miniumi method (Dalkje 1942 l4ohr

1947) and boundary strip method by Blair (1940)

The second approach makes use of smoked karyograph paper instead

of traps in detecting home ranges of individually too-jmarcod rats

The smoked paper placed in unbaited cartons are also arranged in rectangular grid Justice (19b) stated that with this iothod as

many as ton records can be obtained from an individual n a single nighb- the biases of trap inhibition learning and trap fatig inheeAntin the macikand-recapt o method can be avoided and

information suitable forinvestigation of the theoretical probability

density functions of anbmA3activity can be f ond

Difficuties encountered in the study of home range as stated

by Davis (1953b)are 1i Animals do not travel in straight lines between capturs

2 Animalsmay Jlean to go into- traps for food andhence give

too many short distances

3 Traps may not be suitably spaced to indicate maximum

Smovements

4 Transients are included

5 The data give only an index of home range

Stickel (1954) compared some methods and found the so-called

exclusive boundary strip method the mostas accurate In this method

rectangles are constructed the extertial points of capture are

considered centers of the rectanqles the sides of which equal the

distances between traps and bhe corners are so connected su as to

enclose the less area

M4TERAIJS ANRD IMTNODS

By means ofntubered stakes the study areas wera set up in

selected r c fieldsin Siniloan Laguna or--k in these areas

focused on the study vf rat moveOment size n3 fshape of nomui rangeshy

density and srvival rates badod on the captirereleasj-rccap6ire

mathod Prevailul farm pract cIc and we tber ondi Lions were

recorded

Wet season The study area (Figure)- onsisted of si rectangular

paddies totalling about 5400 sq m It was bounded on the northern

side by S~irius grossus grasses on the east by aimarshy area and

shorter grasses mostly Cyperus imbricatus and C compactu on the

south and west by rice fields The eastern half of the field was

Usually left uncultivated during the season as itwas often deeply

flooded The other half was also submerged almost throughout the yeari

In this study area 50 locally made live traps (17 x 28 x 13 cm

were cages) were set 10 meters apart along the dikes The live traps

were baitcd with coconut in the afternoon and inspected early the

net morning Live trapping was done every other week each trapping

period lasting three nights This portion of the study lasted six

months to include the entire wet season crop and the land preparation

and transplanting of thn ne-t ran

rytpeson During the dry season more fields incluling the

previouysl marshy areas were cultivated and planted to rice of the

04 variet A bigger (approrimat-zly 16900 sq m) and more uniform

area (Figure 2) adjacent to thi wet season plot vampO solected for the

rest of the study

A total of 196 collapsiblo live traps wore set 101meters apar

near numbered staice -rrarged in a permanent grid inside the paddies

Traps were baed with sweet potato late in the aiternofn d

inspected carly th4 ieoJt morniiig Trapping s alar dutneevery othoeshy

16

FGRASSES lin

UNCULTIVATED RICE FMlLPD

CULT ATED KELMi RIC

trapplite

1 wet seasipr Study Figurearea with traps Eet along paddy dies

week tocover the following stages of the dry season rico crop 4 weeks after transplanting (WAT) 8 WAT 12 WAT and 1 week after harvest

Each trapping period lasted three nights

In both seasonsy every rat was marked on its first capture by earpunching or-by numbered aluminum ear tags After determiningthe

sex weight reproductive condition and visible parasitism the -

numbered rat in good condition was released at the site of capture

S3ite of first capture and subsequent recaptures were noted During the last trapping period snap traps were set at 15-meter

interval for three consecutive nights around the grid in an attempt to recover marked rats that may have emigrated or shifted home range up

to 75 meters from the cides of the grid

Radio-trackin Radio-tracking uas done a week before harvest of the dry season crop to supplement the recapture data Only seven rats caught at least 10 metpoa +k- deg3Ao ie W- azawere fitted i 4 Wniature transistorized radio transmitters The rats were

monitored at least once every six boar from time of ralease until no further contects could bc made The dlke along line 6 of the grid

served as the reading dike (Figure 2) Most of the points were taken

simultaneously by two radio receivers stationed near points 6-1 and

6-4 The ttap sito in the grid also servod as reference points forW

the approCiniae locations of the rats

Homern andFes ftvemgrts Th distanceLtravoled by a markd or

radio-monitored nh ortc~ - nt was measu ed by baking thesh e distanceiat tuice l -

-18

14

12

SAE S RE M 3

Fiur 2Dr---64 ~ ok s dd S d

19

between two sa esiocontact points saon The distance 6xom

release point was taken int a similar manner Shapo andsize o home range was detormined by the inclusive

boundary strip method (Blair 1940) Boundary strips equal in wIdth thalf tho disatance between traps (f ive meters) were laid off around

the minimum area wherein the rat was locatod The home range was then

dividodinto smaller rectangles and triangles of known dimensions the sumof the smaller areas being equal to the area of the home rangebull

Popuiation densities Population densities were estimated by

models based on capture-releaso-recapture method yhose requirements

were met by the data For thewet season data unly the Petersen model as used by Bailey (192) a- applied For the dry season data

Raynes (1949) graphical model as well as Jollys (0965) abochastic model were also used Tn (1bo eiape apply Jollys (965) stochastic

model the Marchand April datawere combined and the recaoture in

June was excludedasit was made outsido the study grid Marked

arimals 6 ptured Ind recaptured within the same month and animal that

eScaped untagei were ec Ided from tecomputations rPcucatio

densities per hectare werebased on the numbr ofrats inthe

effective census areas as defined by MacTulich (1951)

IIESUIjrSLU~D DISC IOU

l~ igares3a and 3b sihow nAe apparent

s i d lnom-Ir of vlytvn -v marked rats based upon recapturo data

20

777 7 77 77 X7

7 77 7 77

74 77~7 9 V

7 c~ 7 17 7 7

77 1Om~ 7

7 _______ 7

7 7 7

- 7 7 7 7 7 7 7

7 S b 7 7 7 7 7

7 7 7

7 7 7 7 7

~ I7~~~ 7777 7 j777

J~ 7 7 7

7 __ 7

7 77 77 I

7 77

7 7 shy7 71 777I- 1 7

717 77

7 7 -

7 77 77~ 7

7 7 j 7 ~ 7 7

77 I 7 7I

1 77

77 77 77 77 7~~7 7 7~7 77 77

7177 7 7 77 7

7 7 77

7 77 7 77

7~j

7777777 j77 77 7~ 7 77 77~ 7 ~ 777 7U7~77A~I7~7U77777i77 ~ ~ ~ 7

77 777 77

7Ftgure 3a -Appare~2t home range~I of md vhiuaJiy rnazlced9za 7 ba~ed

7 7 - U~Ofl Wet season recaptUXe datampL 77 77 77 7

information suitable forinvestigation of the theoretical probability

density functions of anbmA3activity can be f ond

Difficuties encountered in the study of home range as stated

by Davis (1953b)are 1i Animals do not travel in straight lines between capturs

2 Animalsmay Jlean to go into- traps for food andhence give

too many short distances

3 Traps may not be suitably spaced to indicate maximum

Smovements

4 Transients are included

5 The data give only an index of home range

Stickel (1954) compared some methods and found the so-called

exclusive boundary strip method the mostas accurate In this method

rectangles are constructed the extertial points of capture are

considered centers of the rectanqles the sides of which equal the

distances between traps and bhe corners are so connected su as to

enclose the less area

M4TERAIJS ANRD IMTNODS

By means ofntubered stakes the study areas wera set up in

selected r c fieldsin Siniloan Laguna or--k in these areas

focused on the study vf rat moveOment size n3 fshape of nomui rangeshy

density and srvival rates badod on the captirereleasj-rccap6ire

mathod Prevailul farm pract cIc and we tber ondi Lions were

recorded

Wet season The study area (Figure)- onsisted of si rectangular

paddies totalling about 5400 sq m It was bounded on the northern

side by S~irius grossus grasses on the east by aimarshy area and

shorter grasses mostly Cyperus imbricatus and C compactu on the

south and west by rice fields The eastern half of the field was

Usually left uncultivated during the season as itwas often deeply

flooded The other half was also submerged almost throughout the yeari

In this study area 50 locally made live traps (17 x 28 x 13 cm

were cages) were set 10 meters apart along the dikes The live traps

were baitcd with coconut in the afternoon and inspected early the

net morning Live trapping was done every other week each trapping

period lasting three nights This portion of the study lasted six

months to include the entire wet season crop and the land preparation

and transplanting of thn ne-t ran

rytpeson During the dry season more fields incluling the

previouysl marshy areas were cultivated and planted to rice of the

04 variet A bigger (approrimat-zly 16900 sq m) and more uniform

area (Figure 2) adjacent to thi wet season plot vampO solected for the

rest of the study

A total of 196 collapsiblo live traps wore set 101meters apar

near numbered staice -rrarged in a permanent grid inside the paddies

Traps were baed with sweet potato late in the aiternofn d

inspected carly th4 ieoJt morniiig Trapping s alar dutneevery othoeshy

16

FGRASSES lin

UNCULTIVATED RICE FMlLPD

CULT ATED KELMi RIC

trapplite

1 wet seasipr Study Figurearea with traps Eet along paddy dies

week tocover the following stages of the dry season rico crop 4 weeks after transplanting (WAT) 8 WAT 12 WAT and 1 week after harvest

Each trapping period lasted three nights

In both seasonsy every rat was marked on its first capture by earpunching or-by numbered aluminum ear tags After determiningthe

sex weight reproductive condition and visible parasitism the -

numbered rat in good condition was released at the site of capture

S3ite of first capture and subsequent recaptures were noted During the last trapping period snap traps were set at 15-meter

interval for three consecutive nights around the grid in an attempt to recover marked rats that may have emigrated or shifted home range up

to 75 meters from the cides of the grid

Radio-trackin Radio-tracking uas done a week before harvest of the dry season crop to supplement the recapture data Only seven rats caught at least 10 metpoa +k- deg3Ao ie W- azawere fitted i 4 Wniature transistorized radio transmitters The rats were

monitored at least once every six boar from time of ralease until no further contects could bc made The dlke along line 6 of the grid

served as the reading dike (Figure 2) Most of the points were taken

simultaneously by two radio receivers stationed near points 6-1 and

6-4 The ttap sito in the grid also servod as reference points forW

the approCiniae locations of the rats

Homern andFes ftvemgrts Th distanceLtravoled by a markd or

radio-monitored nh ortc~ - nt was measu ed by baking thesh e distanceiat tuice l -

-18

14

12

SAE S RE M 3

Fiur 2Dr---64 ~ ok s dd S d

19

between two sa esiocontact points saon The distance 6xom

release point was taken int a similar manner Shapo andsize o home range was detormined by the inclusive

boundary strip method (Blair 1940) Boundary strips equal in wIdth thalf tho disatance between traps (f ive meters) were laid off around

the minimum area wherein the rat was locatod The home range was then

dividodinto smaller rectangles and triangles of known dimensions the sumof the smaller areas being equal to the area of the home rangebull

Popuiation densities Population densities were estimated by

models based on capture-releaso-recapture method yhose requirements

were met by the data For thewet season data unly the Petersen model as used by Bailey (192) a- applied For the dry season data

Raynes (1949) graphical model as well as Jollys (0965) abochastic model were also used Tn (1bo eiape apply Jollys (965) stochastic

model the Marchand April datawere combined and the recaoture in

June was excludedasit was made outsido the study grid Marked

arimals 6 ptured Ind recaptured within the same month and animal that

eScaped untagei were ec Ided from tecomputations rPcucatio

densities per hectare werebased on the numbr ofrats inthe

effective census areas as defined by MacTulich (1951)

IIESUIjrSLU~D DISC IOU

l~ igares3a and 3b sihow nAe apparent

s i d lnom-Ir of vlytvn -v marked rats based upon recapturo data

20

777 7 77 77 X7

7 77 7 77

74 77~7 9 V

7 c~ 7 17 7 7

77 1Om~ 7

7 _______ 7

7 7 7

- 7 7 7 7 7 7 7

7 S b 7 7 7 7 7

7 7 7

7 7 7 7 7

~ I7~~~ 7777 7 j777

J~ 7 7 7

7 __ 7

7 77 77 I

7 77

7 7 shy7 71 777I- 1 7

717 77

7 7 -

7 77 77~ 7

7 7 j 7 ~ 7 7

77 I 7 7I

1 77

77 77 77 77 7~~7 7 7~7 77 77

7177 7 7 77 7

7 7 77

7 77 7 77

7~j

7777777 j77 77 7~ 7 77 77~ 7 ~ 777 7U7~77A~I7~7U77777i77 ~ ~ ~ 7

77 777 77

7Ftgure 3a -Appare~2t home range~I of md vhiuaJiy rnazlced9za 7 ba~ed

7 7 - U~Ofl Wet season recaptUXe datampL 77 77 77 7

Wet season The study area (Figure)- onsisted of si rectangular

paddies totalling about 5400 sq m It was bounded on the northern

side by S~irius grossus grasses on the east by aimarshy area and

shorter grasses mostly Cyperus imbricatus and C compactu on the

south and west by rice fields The eastern half of the field was

Usually left uncultivated during the season as itwas often deeply

flooded The other half was also submerged almost throughout the yeari

In this study area 50 locally made live traps (17 x 28 x 13 cm

were cages) were set 10 meters apart along the dikes The live traps

were baitcd with coconut in the afternoon and inspected early the

net morning Live trapping was done every other week each trapping

period lasting three nights This portion of the study lasted six

months to include the entire wet season crop and the land preparation

and transplanting of thn ne-t ran

rytpeson During the dry season more fields incluling the

previouysl marshy areas were cultivated and planted to rice of the

04 variet A bigger (approrimat-zly 16900 sq m) and more uniform

area (Figure 2) adjacent to thi wet season plot vampO solected for the

rest of the study

A total of 196 collapsiblo live traps wore set 101meters apar

near numbered staice -rrarged in a permanent grid inside the paddies

Traps were baed with sweet potato late in the aiternofn d

inspected carly th4 ieoJt morniiig Trapping s alar dutneevery othoeshy

16

FGRASSES lin

UNCULTIVATED RICE FMlLPD

CULT ATED KELMi RIC

trapplite

1 wet seasipr Study Figurearea with traps Eet along paddy dies

week tocover the following stages of the dry season rico crop 4 weeks after transplanting (WAT) 8 WAT 12 WAT and 1 week after harvest

Each trapping period lasted three nights

In both seasonsy every rat was marked on its first capture by earpunching or-by numbered aluminum ear tags After determiningthe

sex weight reproductive condition and visible parasitism the -

numbered rat in good condition was released at the site of capture

S3ite of first capture and subsequent recaptures were noted During the last trapping period snap traps were set at 15-meter

interval for three consecutive nights around the grid in an attempt to recover marked rats that may have emigrated or shifted home range up

to 75 meters from the cides of the grid

Radio-trackin Radio-tracking uas done a week before harvest of the dry season crop to supplement the recapture data Only seven rats caught at least 10 metpoa +k- deg3Ao ie W- azawere fitted i 4 Wniature transistorized radio transmitters The rats were

monitored at least once every six boar from time of ralease until no further contects could bc made The dlke along line 6 of the grid

served as the reading dike (Figure 2) Most of the points were taken

simultaneously by two radio receivers stationed near points 6-1 and

6-4 The ttap sito in the grid also servod as reference points forW

the approCiniae locations of the rats

Homern andFes ftvemgrts Th distanceLtravoled by a markd or

radio-monitored nh ortc~ - nt was measu ed by baking thesh e distanceiat tuice l -

-18

14

12

SAE S RE M 3

Fiur 2Dr---64 ~ ok s dd S d

19

between two sa esiocontact points saon The distance 6xom

release point was taken int a similar manner Shapo andsize o home range was detormined by the inclusive

boundary strip method (Blair 1940) Boundary strips equal in wIdth thalf tho disatance between traps (f ive meters) were laid off around

the minimum area wherein the rat was locatod The home range was then

dividodinto smaller rectangles and triangles of known dimensions the sumof the smaller areas being equal to the area of the home rangebull

Popuiation densities Population densities were estimated by

models based on capture-releaso-recapture method yhose requirements

were met by the data For thewet season data unly the Petersen model as used by Bailey (192) a- applied For the dry season data

Raynes (1949) graphical model as well as Jollys (0965) abochastic model were also used Tn (1bo eiape apply Jollys (965) stochastic

model the Marchand April datawere combined and the recaoture in

June was excludedasit was made outsido the study grid Marked

arimals 6 ptured Ind recaptured within the same month and animal that

eScaped untagei were ec Ided from tecomputations rPcucatio

densities per hectare werebased on the numbr ofrats inthe

effective census areas as defined by MacTulich (1951)

IIESUIjrSLU~D DISC IOU

l~ igares3a and 3b sihow nAe apparent

s i d lnom-Ir of vlytvn -v marked rats based upon recapturo data

20

777 7 77 77 X7

7 77 7 77

74 77~7 9 V

7 c~ 7 17 7 7

77 1Om~ 7

7 _______ 7

7 7 7

- 7 7 7 7 7 7 7

7 S b 7 7 7 7 7

7 7 7

7 7 7 7 7

~ I7~~~ 7777 7 j777

J~ 7 7 7

7 __ 7

7 77 77 I

7 77

7 7 shy7 71 777I- 1 7

717 77

7 7 -

7 77 77~ 7

7 7 j 7 ~ 7 7

77 I 7 7I

1 77

77 77 77 77 7~~7 7 7~7 77 77

7177 7 7 77 7

7 7 77

7 77 7 77

7~j

7777777 j77 77 7~ 7 77 77~ 7 ~ 777 7U7~77A~I7~7U77777i77 ~ ~ ~ 7

77 777 77

7Ftgure 3a -Appare~2t home range~I of md vhiuaJiy rnazlced9za 7 ba~ed

7 7 - U~Ofl Wet season recaptUXe datampL 77 77 77 7

16

FGRASSES lin

UNCULTIVATED RICE FMlLPD

CULT ATED KELMi RIC

trapplite

1 wet seasipr Study Figurearea with traps Eet along paddy dies

week tocover the following stages of the dry season rico crop 4 weeks after transplanting (WAT) 8 WAT 12 WAT and 1 week after harvest

Each trapping period lasted three nights

In both seasonsy every rat was marked on its first capture by earpunching or-by numbered aluminum ear tags After determiningthe

sex weight reproductive condition and visible parasitism the -

numbered rat in good condition was released at the site of capture

S3ite of first capture and subsequent recaptures were noted During the last trapping period snap traps were set at 15-meter

interval for three consecutive nights around the grid in an attempt to recover marked rats that may have emigrated or shifted home range up

to 75 meters from the cides of the grid

Radio-trackin Radio-tracking uas done a week before harvest of the dry season crop to supplement the recapture data Only seven rats caught at least 10 metpoa +k- deg3Ao ie W- azawere fitted i 4 Wniature transistorized radio transmitters The rats were

monitored at least once every six boar from time of ralease until no further contects could bc made The dlke along line 6 of the grid

served as the reading dike (Figure 2) Most of the points were taken

simultaneously by two radio receivers stationed near points 6-1 and

6-4 The ttap sito in the grid also servod as reference points forW

the approCiniae locations of the rats

Homern andFes ftvemgrts Th distanceLtravoled by a markd or

radio-monitored nh ortc~ - nt was measu ed by baking thesh e distanceiat tuice l -

-18

14

12

SAE S RE M 3

Fiur 2Dr---64 ~ ok s dd S d

19

between two sa esiocontact points saon The distance 6xom

release point was taken int a similar manner Shapo andsize o home range was detormined by the inclusive

boundary strip method (Blair 1940) Boundary strips equal in wIdth thalf tho disatance between traps (f ive meters) were laid off around

the minimum area wherein the rat was locatod The home range was then

dividodinto smaller rectangles and triangles of known dimensions the sumof the smaller areas being equal to the area of the home rangebull

Popuiation densities Population densities were estimated by

models based on capture-releaso-recapture method yhose requirements

were met by the data For thewet season data unly the Petersen model as used by Bailey (192) a- applied For the dry season data

Raynes (1949) graphical model as well as Jollys (0965) abochastic model were also used Tn (1bo eiape apply Jollys (965) stochastic

model the Marchand April datawere combined and the recaoture in

June was excludedasit was made outsido the study grid Marked

arimals 6 ptured Ind recaptured within the same month and animal that

eScaped untagei were ec Ided from tecomputations rPcucatio

densities per hectare werebased on the numbr ofrats inthe

effective census areas as defined by MacTulich (1951)

IIESUIjrSLU~D DISC IOU

l~ igares3a and 3b sihow nAe apparent

s i d lnom-Ir of vlytvn -v marked rats based upon recapturo data

20

777 7 77 77 X7

7 77 7 77

74 77~7 9 V

7 c~ 7 17 7 7

77 1Om~ 7

7 _______ 7

7 7 7

- 7 7 7 7 7 7 7

7 S b 7 7 7 7 7

7 7 7

7 7 7 7 7

~ I7~~~ 7777 7 j777

J~ 7 7 7

7 __ 7

7 77 77 I

7 77

7 7 shy7 71 777I- 1 7

717 77

7 7 -

7 77 77~ 7

7 7 j 7 ~ 7 7

77 I 7 7I

1 77

77 77 77 77 7~~7 7 7~7 77 77

7177 7 7 77 7

7 7 77

7 77 7 77

7~j

7777777 j77 77 7~ 7 77 77~ 7 ~ 777 7U7~77A~I7~7U77777i77 ~ ~ ~ 7

77 777 77

7Ftgure 3a -Appare~2t home range~I of md vhiuaJiy rnazlced9za 7 ba~ed

7 7 - U~Ofl Wet season recaptUXe datampL 77 77 77 7

week tocover the following stages of the dry season rico crop 4 weeks after transplanting (WAT) 8 WAT 12 WAT and 1 week after harvest

Each trapping period lasted three nights

In both seasonsy every rat was marked on its first capture by earpunching or-by numbered aluminum ear tags After determiningthe

sex weight reproductive condition and visible parasitism the -

numbered rat in good condition was released at the site of capture

S3ite of first capture and subsequent recaptures were noted During the last trapping period snap traps were set at 15-meter

interval for three consecutive nights around the grid in an attempt to recover marked rats that may have emigrated or shifted home range up

to 75 meters from the cides of the grid

Radio-trackin Radio-tracking uas done a week before harvest of the dry season crop to supplement the recapture data Only seven rats caught at least 10 metpoa +k- deg3Ao ie W- azawere fitted i 4 Wniature transistorized radio transmitters The rats were

monitored at least once every six boar from time of ralease until no further contects could bc made The dlke along line 6 of the grid

served as the reading dike (Figure 2) Most of the points were taken

simultaneously by two radio receivers stationed near points 6-1 and

6-4 The ttap sito in the grid also servod as reference points forW

the approCiniae locations of the rats

Homern andFes ftvemgrts Th distanceLtravoled by a markd or

radio-monitored nh ortc~ - nt was measu ed by baking thesh e distanceiat tuice l -

-18

14

12

SAE S RE M 3

Fiur 2Dr---64 ~ ok s dd S d

19

between two sa esiocontact points saon The distance 6xom

release point was taken int a similar manner Shapo andsize o home range was detormined by the inclusive

boundary strip method (Blair 1940) Boundary strips equal in wIdth thalf tho disatance between traps (f ive meters) were laid off around

the minimum area wherein the rat was locatod The home range was then

dividodinto smaller rectangles and triangles of known dimensions the sumof the smaller areas being equal to the area of the home rangebull

Popuiation densities Population densities were estimated by

models based on capture-releaso-recapture method yhose requirements

were met by the data For thewet season data unly the Petersen model as used by Bailey (192) a- applied For the dry season data

Raynes (1949) graphical model as well as Jollys (0965) abochastic model were also used Tn (1bo eiape apply Jollys (965) stochastic

model the Marchand April datawere combined and the recaoture in

June was excludedasit was made outsido the study grid Marked

arimals 6 ptured Ind recaptured within the same month and animal that

eScaped untagei were ec Ided from tecomputations rPcucatio

densities per hectare werebased on the numbr ofrats inthe

effective census areas as defined by MacTulich (1951)

IIESUIjrSLU~D DISC IOU

l~ igares3a and 3b sihow nAe apparent

s i d lnom-Ir of vlytvn -v marked rats based upon recapturo data

20

777 7 77 77 X7

7 77 7 77

74 77~7 9 V

7 c~ 7 17 7 7

77 1Om~ 7

7 _______ 7

7 7 7

- 7 7 7 7 7 7 7

7 S b 7 7 7 7 7

7 7 7

7 7 7 7 7

~ I7~~~ 7777 7 j777

J~ 7 7 7

7 __ 7

7 77 77 I

7 77

7 7 shy7 71 777I- 1 7

717 77

7 7 -

7 77 77~ 7

7 7 j 7 ~ 7 7

77 I 7 7I

1 77

77 77 77 77 7~~7 7 7~7 77 77

7177 7 7 77 7

7 7 77

7 77 7 77

7~j

7777777 j77 77 7~ 7 77 77~ 7 ~ 777 7U7~77A~I7~7U77777i77 ~ ~ ~ 7

77 777 77

7Ftgure 3a -Appare~2t home range~I of md vhiuaJiy rnazlced9za 7 ba~ed

7 7 - U~Ofl Wet season recaptUXe datampL 77 77 77 7

-18

14

12

SAE S RE M 3

Fiur 2Dr---64 ~ ok s dd S d

19

between two sa esiocontact points saon The distance 6xom

release point was taken int a similar manner Shapo andsize o home range was detormined by the inclusive

boundary strip method (Blair 1940) Boundary strips equal in wIdth thalf tho disatance between traps (f ive meters) were laid off around

the minimum area wherein the rat was locatod The home range was then

dividodinto smaller rectangles and triangles of known dimensions the sumof the smaller areas being equal to the area of the home rangebull

Popuiation densities Population densities were estimated by

models based on capture-releaso-recapture method yhose requirements

were met by the data For thewet season data unly the Petersen model as used by Bailey (192) a- applied For the dry season data

Raynes (1949) graphical model as well as Jollys (0965) abochastic model were also used Tn (1bo eiape apply Jollys (965) stochastic

model the Marchand April datawere combined and the recaoture in

June was excludedasit was made outsido the study grid Marked

arimals 6 ptured Ind recaptured within the same month and animal that

eScaped untagei were ec Ided from tecomputations rPcucatio

densities per hectare werebased on the numbr ofrats inthe

effective census areas as defined by MacTulich (1951)

IIESUIjrSLU~D DISC IOU

l~ igares3a and 3b sihow nAe apparent

s i d lnom-Ir of vlytvn -v marked rats based upon recapturo data

20

777 7 77 77 X7

7 77 7 77

74 77~7 9 V

7 c~ 7 17 7 7

77 1Om~ 7

7 _______ 7

7 7 7

- 7 7 7 7 7 7 7

7 S b 7 7 7 7 7

7 7 7

7 7 7 7 7

~ I7~~~ 7777 7 j777

J~ 7 7 7

7 __ 7

7 77 77 I

7 77

7 7 shy7 71 777I- 1 7

717 77

7 7 -

7 77 77~ 7

7 7 j 7 ~ 7 7

77 I 7 7I

1 77

77 77 77 77 7~~7 7 7~7 77 77

7177 7 7 77 7

7 7 77

7 77 7 77

7~j

7777777 j77 77 7~ 7 77 77~ 7 ~ 777 7U7~77A~I7~7U77777i77 ~ ~ ~ 7

77 777 77

7Ftgure 3a -Appare~2t home range~I of md vhiuaJiy rnazlced9za 7 ba~ed

7 7 - U~Ofl Wet season recaptUXe datampL 77 77 77 7

19

between two sa esiocontact points saon The distance 6xom

release point was taken int a similar manner Shapo andsize o home range was detormined by the inclusive

boundary strip method (Blair 1940) Boundary strips equal in wIdth thalf tho disatance between traps (f ive meters) were laid off around

the minimum area wherein the rat was locatod The home range was then

dividodinto smaller rectangles and triangles of known dimensions the sumof the smaller areas being equal to the area of the home rangebull

Popuiation densities Population densities were estimated by

models based on capture-releaso-recapture method yhose requirements

were met by the data For thewet season data unly the Petersen model as used by Bailey (192) a- applied For the dry season data

Raynes (1949) graphical model as well as Jollys (0965) abochastic model were also used Tn (1bo eiape apply Jollys (965) stochastic

model the Marchand April datawere combined and the recaoture in

June was excludedasit was made outsido the study grid Marked

arimals 6 ptured Ind recaptured within the same month and animal that

eScaped untagei were ec Ided from tecomputations rPcucatio

densities per hectare werebased on the numbr ofrats inthe

effective census areas as defined by MacTulich (1951)

IIESUIjrSLU~D DISC IOU

l~ igares3a and 3b sihow nAe apparent

s i d lnom-Ir of vlytvn -v marked rats based upon recapturo data

20

777 7 77 77 X7

7 77 7 77

74 77~7 9 V

7 c~ 7 17 7 7

77 1Om~ 7

7 _______ 7

7 7 7

- 7 7 7 7 7 7 7

7 S b 7 7 7 7 7

7 7 7

7 7 7 7 7

~ I7~~~ 7777 7 j777

J~ 7 7 7

7 __ 7

7 77 77 I

7 77

7 7 shy7 71 777I- 1 7

717 77

7 7 -

7 77 77~ 7

7 7 j 7 ~ 7 7

77 I 7 7I

1 77

77 77 77 77 7~~7 7 7~7 77 77

7177 7 7 77 7

7 7 77

7 77 7 77

7~j

7777777 j77 77 7~ 7 77 77~ 7 ~ 777 7U7~77A~I7~7U77777i77 ~ ~ ~ 7

77 777 77

7Ftgure 3a -Appare~2t home range~I of md vhiuaJiy rnazlced9za 7 ba~ed

7 7 - U~Ofl Wet season recaptUXe datampL 77 77 77 7

20

777 7 77 77 X7

7 77 7 77

74 77~7 9 V

7 c~ 7 17 7 7

77 1Om~ 7

7 _______ 7

7 7 7

- 7 7 7 7 7 7 7

7 S b 7 7 7 7 7

7 7 7

7 7 7 7 7

~ I7~~~ 7777 7 j777

J~ 7 7 7

7 __ 7

7 77 77 I

7 77

7 7 shy7 71 777I- 1 7

717 77

7 7 -

7 77 77~ 7

7 7 j 7 ~ 7 7

77 I 7 7I

1 77

77 77 77 77 7~~7 7 7~7 77 77

7177 7 7 77 7

7 7 77

7 77 7 77

7~j

7777777 j77 77 7~ 7 77 77~ 7 ~ 777 7U7~77A~I7~7U77777i77 ~ ~ ~ 7

77 777 77

7Ftgure 3a -Appare~2t home range~I of md vhiuaJiy rnazlced9za 7 ba~ed

7 7 - U~Ofl Wet season recaptUXe datampL 77 77 77 7

21

V

I

A I I I E]

I I

I I I I 2 - C shy

I

I II

F

I I ~ lii1

3b Figuzt3 Appareiit home ranges cC ndivid~J2~ r~arked rate based

A ~ a ~ dr~~ vtn~ dw~vp Tht~

Ailrats were recaptured only once over a prod of four months during

the wet season and one month in the dry season Individual home ranges

based on the two stations measured from 300 to 600-sq m (wet season data) andfom 200 to 800 sq m (dry season dat) Overappig of

home rangeswas evident Transients were aist included as indicated by

one home range extending beyond the study grid

Sizes and shapes of Individual home ranges of SD radio-monitorod

rats are shown in Figure 4a The homo ranges of the radio-monitored

ratsf likewise were not mutually exclusive Most of the deteoted

home ranges extended well beyond the study area

The approimate sizes of the home ranges based on two to eight

stations were from 400 to 4080 sq m twico up to five times larger

than the bizes based on two stations (recapture data) Based on the

second up to the last day radio-tracking data (throe to four stations)

maxlmum home range measured apprndmotely 2400 sq m These datA

could indicate that thc observed range size is proportional to the

-number oZ contacts or captures of the same individual as reported by

Stickel (1954) Range size increases with more rocapturo until a

levelapprocimating tho true range is reached Davis (1953b) saggested

the rieed to recapture a inglo individial about15-20 times to obtain

fidequate -data

A-Areas female r t 0 and Fbynd D ioro occpied by juvenile s

adu aes0 Whe aresB)2nid E worecupiod byQdult foead raLs

(igure 4a) Th JUvenA oa ppuarcd Lo havo larger borne ranngos

1925 08a 6q m tti thu adult (4)2160 3q mn) The adult malo

I i i 9 - 9 9 shy shy

Fi ur 4 i bull

iii aInc bondr hom rage of si I

f ~ [~

10m-n U

--

rate - h--e rane of 0iradio monitored[

andfemles had home ranges of similar sizes (Up to 2160 and 2100 sq in

respectively) The rolative sizes of theobserved homie ranges with

respect to age and sex agree with the findings of Stickel (1954) and

Getz (1961) on woodmico and other species Subadults may cover more

area since they are not as established as do adults in their home

ranges T he adult female inside area E may possibj bo a transient

to tho atrea A the available data cannot describe its apparent home

range

Movement patterns of radio-monitored rats are shomin in Figure 4b

Ratsestablishod in thoir respective home ranges m y be rratic but

theysoom to revolve about an imaginary point which Hayne (1949)

called center of activity

Distances traveled between two successivo stations distances from

site of release and tho time involved to cover such distances are

shown in Table la for recaptured rats and Table lb for radioshy

monitored rats

Table la Movement offirkcd rats det-cted by recapbaro metod

Distance ec Ago traveled bull Timebulleelaosed

Male Adult 20 4-montns-Male Adult 0 months Male Adult ~ 10 K Iday Male Male

Ae tlt Juvenilo

50 10

1 month days

Female Adult 63 2 weeks FemaleAul 32 1dy

25

+ 7 shy

-- -- ----shy

S-7-shy

1~~~77 7

gre 4b -L M D o e--ment pat nI -f nt xe rb-

X Ml~eaO pointrIEQENDno of raji mniord t13

Table lb Movement of radiom-monitored rats

Distance Distance from Sex ge traveled release site Time elapsed

(in (i )

Male Adult 30 30 6 hours

Mae Adlt 4+5 445 3 hours 40 10 3 hours 50 22 6 hours 50 45 6hours 40 10 6 hours 10 -20r 2days

522 6 hours 32 20 6 hours

Female juvenile 5535 3 hours 3 30P 3 hours

10 6 hours

15 20 15

12 6

hours hours

Female J avonile 35 35 3 hours 25 60 3 hours 15 70 6 hours 25 50 6 hours 230 2 days 25 55 6 hours 7C 83 iay

Feme Adult 80 80 3 hou s Adult- 3 0ota

Fonale Adult 330 i 30 3hDo

20 50 3 hours

4 40

z

1540

045 -shy70

07

6 hoirs 12 hors 6 hours+6 co=

27

Disregarding the t ime element the-average deParture o f marke

rats from their site of release was 2667 and 3875meters during the

wetand dry seasons respectively Radio-monitored rats had an average

of 4 0 18-meter departure from site of release From the point of

release juveniles ranged 10-83 meters adult males ranged 10-52

meters and adult females ranged 30-80 meters

Flash floods brought about by heavy rains weeding harvesting

and land preparation did not displace the rats to groat extent

similar to the findings of LaVoie et al (1971) Maximum departure

from point of release as disclosed by the recapture data under these

conditions was only 63 meters Likewise some rats remained within

50 metors from point of release for as long as four months Rats may

live long in their established home ranges and may not be immediately

displaced by usual farm activities without incorporating control

Population densities Tables 2a and 2b show the rocapture data

along with the monthly trap indices over the entire study period

Listed in Tables 3a and 3b are the population densities and

variances as estimated-by different models

Table 2a Wet soason recapture data

-Month--Tra Index Sa epte Mot T dReocapture Crop Stage

Same period Others rFxm activity

September 326 0 0 Transplanting

October 294 0 0 Booting

November 222 0 0 Mturity

December 403 0 0 Area cleared

January 32 0 1 2 Land preparatiot

February 2 0 0 Transplanting

Table 2b Dry season recapturo data

RIndex Crop Stage )ame period Others Farm activity

Month Tra Rocapture

ro-bootingMr3h 0 re1

Boot ing

April 1 0 0 WoedingMatlritj

My 47 1 1 rvest-ig

June 50 A K30 havst

L -

29

Table 3a Monthly wet season densities as estimated by the Petersen method

th Densitya Variance

October 132 7260 November 30 50820 December 1824 66100 January 1020 24400 February 693 213444

aaBasedon tho cumulative total number of marked animalssince Sbptemoer-

Table 3b Monthly dryseason densities as determined by difforent models based onthe capture-release-recapturo technique

ModelHayne Jolly Peterson Month NN se N 0-e

March 25 a 671a 15

Aprla a a a

May 160 55b 732 2 4 90

340d j1832d

aInsufficient data model not applicabl

becapture within bhe same month are exciuded

0Based on tne number of tagged animals atarting from tho trappingto which the recapture animal belonged

-dB6sdon the zotal number of animals Lagged archwine

30

L enunat te requenyof recapturesre ti6 to th total number of tagged individuals affects the precision of the est imates (Table 3b) -The Petersen and iiayne estimates cre ss preciso(seb 11832) _when based on the cumulative total numbor ofanimals

tagged since the first trapping period than When based on the total number tagged from the trapping period to which the recaptured animal belonged (se 490) moreAs tagged animals are released during the first period and few are recaptured during the next period the Petersen and Hayne Models tend toovrestimato the population size or

if they ever come close to the true value the confidence intervals are-widely spread On the other hand the Jolly model tends tounderestimate the population size (N 55 se = 735) as comped

to Petersens (N = 120 490)se and to hynes ( N- 160) when based on very ew recaptures few samples and low trap indices

(Table 2b) Dilution rates incnrporated in the Jolly model also cannot be determined due to insuffici-nt recaptoxe data

The effeotive census areas (MacLulich 1951) wore 99 sq ]m and 28548 sq m for the wet and dry seasons respectively Based on

thschanguP J11 population densities per heutarLampIert3ustitnttd using the Petersen method an( presented in Figure5 Poolaticn sizes were higher in the weL season than in tho Cy season I oth seasps density increased tward the matrity of the crop From Novjaber to

early Decembar (wet-Sea on) thec3 fields wplusmnih t m2tlkgfw wezo abandonedby +hp farmtirs -Dring this t it the ric plantsin

the studyr are andits v InItyi most ttally damagod abs

31

2000

1900

1800p

900

- I 800

a o 700

600

P40

3004

2001

100]

Oct Nov ~Dee Jan F-qb - Ar ipril a

Ionth

~Figure 5 MonthlyV population ctenpity pur hec bae

Wed s likewise filled the remaining -spaces inside the -paddies and on

the dikes The resiulting increase in covor and food supl ma hve favored anot increase in population sizeThis could aloexplain the

populatioi build up in November which became evident in the laer-pa2t

of December

It was noted that the proportion of males in the monthly samples

was negat ively correlated with poptilation1levol Cr=-87) No

sBignificantcorrelation Was- found-between population density and the proportion of juveniles in the samples

Trappabilitv Table 4 shows a very low dry season probability of survival of marked animalswithin the stadygrid (r=022) This Could mean that for every100marked rats roughl o lytormained

inside the grid for-the next months trappi g period therest ether

died or moved outside the study axea-

Table 4 Diy season population parajotos estimated by Jollys4tochastiedc modejl

Month N V(N)

-March-April 022 414

My 55

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

Ailrats were recaptured only once over a prod of four months during

the wet season and one month in the dry season Individual home ranges

based on the two stations measured from 300 to 600-sq m (wet season data) andfom 200 to 800 sq m (dry season dat) Overappig of

home rangeswas evident Transients were aist included as indicated by

one home range extending beyond the study grid

Sizes and shapes of Individual home ranges of SD radio-monitorod

rats are shown in Figure 4a The homo ranges of the radio-monitored

ratsf likewise were not mutually exclusive Most of the deteoted

home ranges extended well beyond the study area

The approimate sizes of the home ranges based on two to eight

stations were from 400 to 4080 sq m twico up to five times larger

than the bizes based on two stations (recapture data) Based on the

second up to the last day radio-tracking data (throe to four stations)

maxlmum home range measured apprndmotely 2400 sq m These datA

could indicate that thc observed range size is proportional to the

-number oZ contacts or captures of the same individual as reported by

Stickel (1954) Range size increases with more rocapturo until a

levelapprocimating tho true range is reached Davis (1953b) saggested

the rieed to recapture a inglo individial about15-20 times to obtain

fidequate -data

A-Areas female r t 0 and Fbynd D ioro occpied by juvenile s

adu aes0 Whe aresB)2nid E worecupiod byQdult foead raLs

(igure 4a) Th JUvenA oa ppuarcd Lo havo larger borne ranngos

1925 08a 6q m tti thu adult (4)2160 3q mn) The adult malo

I i i 9 - 9 9 shy shy

Fi ur 4 i bull

iii aInc bondr hom rage of si I

f ~ [~

10m-n U

--

rate - h--e rane of 0iradio monitored[

andfemles had home ranges of similar sizes (Up to 2160 and 2100 sq in

respectively) The rolative sizes of theobserved homie ranges with

respect to age and sex agree with the findings of Stickel (1954) and

Getz (1961) on woodmico and other species Subadults may cover more

area since they are not as established as do adults in their home

ranges T he adult female inside area E may possibj bo a transient

to tho atrea A the available data cannot describe its apparent home

range

Movement patterns of radio-monitored rats are shomin in Figure 4b

Ratsestablishod in thoir respective home ranges m y be rratic but

theysoom to revolve about an imaginary point which Hayne (1949)

called center of activity

Distances traveled between two successivo stations distances from

site of release and tho time involved to cover such distances are

shown in Table la for recaptured rats and Table lb for radioshy

monitored rats

Table la Movement offirkcd rats det-cted by recapbaro metod

Distance ec Ago traveled bull Timebulleelaosed

Male Adult 20 4-montns-Male Adult 0 months Male Adult ~ 10 K Iday Male Male

Ae tlt Juvenilo

50 10

1 month days

Female Adult 63 2 weeks FemaleAul 32 1dy

25

+ 7 shy

-- -- ----shy

S-7-shy

1~~~77 7

gre 4b -L M D o e--ment pat nI -f nt xe rb-

X Ml~eaO pointrIEQENDno of raji mniord t13

Table lb Movement of radiom-monitored rats

Distance Distance from Sex ge traveled release site Time elapsed

(in (i )

Male Adult 30 30 6 hours

Mae Adlt 4+5 445 3 hours 40 10 3 hours 50 22 6 hours 50 45 6hours 40 10 6 hours 10 -20r 2days

522 6 hours 32 20 6 hours

Female juvenile 5535 3 hours 3 30P 3 hours

10 6 hours

15 20 15

12 6

hours hours

Female J avonile 35 35 3 hours 25 60 3 hours 15 70 6 hours 25 50 6 hours 230 2 days 25 55 6 hours 7C 83 iay

Feme Adult 80 80 3 hou s Adult- 3 0ota

Fonale Adult 330 i 30 3hDo

20 50 3 hours

4 40

z

1540

045 -shy70

07

6 hoirs 12 hors 6 hours+6 co=

27

Disregarding the t ime element the-average deParture o f marke

rats from their site of release was 2667 and 3875meters during the

wetand dry seasons respectively Radio-monitored rats had an average

of 4 0 18-meter departure from site of release From the point of

release juveniles ranged 10-83 meters adult males ranged 10-52

meters and adult females ranged 30-80 meters

Flash floods brought about by heavy rains weeding harvesting

and land preparation did not displace the rats to groat extent

similar to the findings of LaVoie et al (1971) Maximum departure

from point of release as disclosed by the recapture data under these

conditions was only 63 meters Likewise some rats remained within

50 metors from point of release for as long as four months Rats may

live long in their established home ranges and may not be immediately

displaced by usual farm activities without incorporating control

Population densities Tables 2a and 2b show the rocapture data

along with the monthly trap indices over the entire study period

Listed in Tables 3a and 3b are the population densities and

variances as estimated-by different models

Table 2a Wet soason recapture data

-Month--Tra Index Sa epte Mot T dReocapture Crop Stage

Same period Others rFxm activity

September 326 0 0 Transplanting

October 294 0 0 Booting

November 222 0 0 Mturity

December 403 0 0 Area cleared

January 32 0 1 2 Land preparatiot

February 2 0 0 Transplanting

Table 2b Dry season recapturo data

RIndex Crop Stage )ame period Others Farm activity

Month Tra Rocapture

ro-bootingMr3h 0 re1

Boot ing

April 1 0 0 WoedingMatlritj

My 47 1 1 rvest-ig

June 50 A K30 havst

L -

29

Table 3a Monthly wet season densities as estimated by the Petersen method

th Densitya Variance

October 132 7260 November 30 50820 December 1824 66100 January 1020 24400 February 693 213444

aaBasedon tho cumulative total number of marked animalssince Sbptemoer-

Table 3b Monthly dryseason densities as determined by difforent models based onthe capture-release-recapturo technique

ModelHayne Jolly Peterson Month NN se N 0-e

March 25 a 671a 15

Aprla a a a

May 160 55b 732 2 4 90

340d j1832d

aInsufficient data model not applicabl

becapture within bhe same month are exciuded

0Based on tne number of tagged animals atarting from tho trappingto which the recapture animal belonged

-dB6sdon the zotal number of animals Lagged archwine

30

L enunat te requenyof recapturesre ti6 to th total number of tagged individuals affects the precision of the est imates (Table 3b) -The Petersen and iiayne estimates cre ss preciso(seb 11832) _when based on the cumulative total numbor ofanimals

tagged since the first trapping period than When based on the total number tagged from the trapping period to which the recaptured animal belonged (se 490) moreAs tagged animals are released during the first period and few are recaptured during the next period the Petersen and Hayne Models tend toovrestimato the population size or

if they ever come close to the true value the confidence intervals are-widely spread On the other hand the Jolly model tends tounderestimate the population size (N 55 se = 735) as comped

to Petersens (N = 120 490)se and to hynes ( N- 160) when based on very ew recaptures few samples and low trap indices

(Table 2b) Dilution rates incnrporated in the Jolly model also cannot be determined due to insuffici-nt recaptoxe data

The effeotive census areas (MacLulich 1951) wore 99 sq ]m and 28548 sq m for the wet and dry seasons respectively Based on

thschanguP J11 population densities per heutarLampIert3ustitnttd using the Petersen method an( presented in Figure5 Poolaticn sizes were higher in the weL season than in tho Cy season I oth seasps density increased tward the matrity of the crop From Novjaber to

early Decembar (wet-Sea on) thec3 fields wplusmnih t m2tlkgfw wezo abandonedby +hp farmtirs -Dring this t it the ric plantsin

the studyr are andits v InItyi most ttally damagod abs

31

2000

1900

1800p

900

- I 800

a o 700

600

P40

3004

2001

100]

Oct Nov ~Dee Jan F-qb - Ar ipril a

Ionth

~Figure 5 MonthlyV population ctenpity pur hec bae

Wed s likewise filled the remaining -spaces inside the -paddies and on

the dikes The resiulting increase in covor and food supl ma hve favored anot increase in population sizeThis could aloexplain the

populatioi build up in November which became evident in the laer-pa2t

of December

It was noted that the proportion of males in the monthly samples

was negat ively correlated with poptilation1levol Cr=-87) No

sBignificantcorrelation Was- found-between population density and the proportion of juveniles in the samples

Trappabilitv Table 4 shows a very low dry season probability of survival of marked animalswithin the stadygrid (r=022) This Could mean that for every100marked rats roughl o lytormained

inside the grid for-the next months trappi g period therest ether

died or moved outside the study axea-

Table 4 Diy season population parajotos estimated by Jollys4tochastiedc modejl

Month N V(N)

-March-April 022 414

My 55

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

I i i 9 - 9 9 shy shy

Fi ur 4 i bull

iii aInc bondr hom rage of si I

f ~ [~

10m-n U

--

rate - h--e rane of 0iradio monitored[

andfemles had home ranges of similar sizes (Up to 2160 and 2100 sq in

respectively) The rolative sizes of theobserved homie ranges with

respect to age and sex agree with the findings of Stickel (1954) and

Getz (1961) on woodmico and other species Subadults may cover more

area since they are not as established as do adults in their home

ranges T he adult female inside area E may possibj bo a transient

to tho atrea A the available data cannot describe its apparent home

range

Movement patterns of radio-monitored rats are shomin in Figure 4b

Ratsestablishod in thoir respective home ranges m y be rratic but

theysoom to revolve about an imaginary point which Hayne (1949)

called center of activity

Distances traveled between two successivo stations distances from

site of release and tho time involved to cover such distances are

shown in Table la for recaptured rats and Table lb for radioshy

monitored rats

Table la Movement offirkcd rats det-cted by recapbaro metod

Distance ec Ago traveled bull Timebulleelaosed

Male Adult 20 4-montns-Male Adult 0 months Male Adult ~ 10 K Iday Male Male

Ae tlt Juvenilo

50 10

1 month days

Female Adult 63 2 weeks FemaleAul 32 1dy

25

+ 7 shy

-- -- ----shy

S-7-shy

1~~~77 7

gre 4b -L M D o e--ment pat nI -f nt xe rb-

X Ml~eaO pointrIEQENDno of raji mniord t13

Table lb Movement of radiom-monitored rats

Distance Distance from Sex ge traveled release site Time elapsed

(in (i )

Male Adult 30 30 6 hours

Mae Adlt 4+5 445 3 hours 40 10 3 hours 50 22 6 hours 50 45 6hours 40 10 6 hours 10 -20r 2days

522 6 hours 32 20 6 hours

Female juvenile 5535 3 hours 3 30P 3 hours

10 6 hours

15 20 15

12 6

hours hours

Female J avonile 35 35 3 hours 25 60 3 hours 15 70 6 hours 25 50 6 hours 230 2 days 25 55 6 hours 7C 83 iay

Feme Adult 80 80 3 hou s Adult- 3 0ota

Fonale Adult 330 i 30 3hDo

20 50 3 hours

4 40

z

1540

045 -shy70

07

6 hoirs 12 hors 6 hours+6 co=

27

Disregarding the t ime element the-average deParture o f marke

rats from their site of release was 2667 and 3875meters during the

wetand dry seasons respectively Radio-monitored rats had an average

of 4 0 18-meter departure from site of release From the point of

release juveniles ranged 10-83 meters adult males ranged 10-52

meters and adult females ranged 30-80 meters

Flash floods brought about by heavy rains weeding harvesting

and land preparation did not displace the rats to groat extent

similar to the findings of LaVoie et al (1971) Maximum departure

from point of release as disclosed by the recapture data under these

conditions was only 63 meters Likewise some rats remained within

50 metors from point of release for as long as four months Rats may

live long in their established home ranges and may not be immediately

displaced by usual farm activities without incorporating control

Population densities Tables 2a and 2b show the rocapture data

along with the monthly trap indices over the entire study period

Listed in Tables 3a and 3b are the population densities and

variances as estimated-by different models

Table 2a Wet soason recapture data

-Month--Tra Index Sa epte Mot T dReocapture Crop Stage

Same period Others rFxm activity

September 326 0 0 Transplanting

October 294 0 0 Booting

November 222 0 0 Mturity

December 403 0 0 Area cleared

January 32 0 1 2 Land preparatiot

February 2 0 0 Transplanting

Table 2b Dry season recapturo data

RIndex Crop Stage )ame period Others Farm activity

Month Tra Rocapture

ro-bootingMr3h 0 re1

Boot ing

April 1 0 0 WoedingMatlritj

My 47 1 1 rvest-ig

June 50 A K30 havst

L -

29

Table 3a Monthly wet season densities as estimated by the Petersen method

th Densitya Variance

October 132 7260 November 30 50820 December 1824 66100 January 1020 24400 February 693 213444

aaBasedon tho cumulative total number of marked animalssince Sbptemoer-

Table 3b Monthly dryseason densities as determined by difforent models based onthe capture-release-recapturo technique

ModelHayne Jolly Peterson Month NN se N 0-e

March 25 a 671a 15

Aprla a a a

May 160 55b 732 2 4 90

340d j1832d

aInsufficient data model not applicabl

becapture within bhe same month are exciuded

0Based on tne number of tagged animals atarting from tho trappingto which the recapture animal belonged

-dB6sdon the zotal number of animals Lagged archwine

30

L enunat te requenyof recapturesre ti6 to th total number of tagged individuals affects the precision of the est imates (Table 3b) -The Petersen and iiayne estimates cre ss preciso(seb 11832) _when based on the cumulative total numbor ofanimals

tagged since the first trapping period than When based on the total number tagged from the trapping period to which the recaptured animal belonged (se 490) moreAs tagged animals are released during the first period and few are recaptured during the next period the Petersen and Hayne Models tend toovrestimato the population size or

if they ever come close to the true value the confidence intervals are-widely spread On the other hand the Jolly model tends tounderestimate the population size (N 55 se = 735) as comped

to Petersens (N = 120 490)se and to hynes ( N- 160) when based on very ew recaptures few samples and low trap indices

(Table 2b) Dilution rates incnrporated in the Jolly model also cannot be determined due to insuffici-nt recaptoxe data

The effeotive census areas (MacLulich 1951) wore 99 sq ]m and 28548 sq m for the wet and dry seasons respectively Based on

thschanguP J11 population densities per heutarLampIert3ustitnttd using the Petersen method an( presented in Figure5 Poolaticn sizes were higher in the weL season than in tho Cy season I oth seasps density increased tward the matrity of the crop From Novjaber to

early Decembar (wet-Sea on) thec3 fields wplusmnih t m2tlkgfw wezo abandonedby +hp farmtirs -Dring this t it the ric plantsin

the studyr are andits v InItyi most ttally damagod abs

31

2000

1900

1800p

900

- I 800

a o 700

600

P40

3004

2001

100]

Oct Nov ~Dee Jan F-qb - Ar ipril a

Ionth

~Figure 5 MonthlyV population ctenpity pur hec bae

Wed s likewise filled the remaining -spaces inside the -paddies and on

the dikes The resiulting increase in covor and food supl ma hve favored anot increase in population sizeThis could aloexplain the

populatioi build up in November which became evident in the laer-pa2t

of December

It was noted that the proportion of males in the monthly samples

was negat ively correlated with poptilation1levol Cr=-87) No

sBignificantcorrelation Was- found-between population density and the proportion of juveniles in the samples

Trappabilitv Table 4 shows a very low dry season probability of survival of marked animalswithin the stadygrid (r=022) This Could mean that for every100marked rats roughl o lytormained

inside the grid for-the next months trappi g period therest ether

died or moved outside the study axea-

Table 4 Diy season population parajotos estimated by Jollys4tochastiedc modejl

Month N V(N)

-March-April 022 414

My 55

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

andfemles had home ranges of similar sizes (Up to 2160 and 2100 sq in

respectively) The rolative sizes of theobserved homie ranges with

respect to age and sex agree with the findings of Stickel (1954) and

Getz (1961) on woodmico and other species Subadults may cover more

area since they are not as established as do adults in their home

ranges T he adult female inside area E may possibj bo a transient

to tho atrea A the available data cannot describe its apparent home

range

Movement patterns of radio-monitored rats are shomin in Figure 4b

Ratsestablishod in thoir respective home ranges m y be rratic but

theysoom to revolve about an imaginary point which Hayne (1949)

called center of activity

Distances traveled between two successivo stations distances from

site of release and tho time involved to cover such distances are

shown in Table la for recaptured rats and Table lb for radioshy

monitored rats

Table la Movement offirkcd rats det-cted by recapbaro metod

Distance ec Ago traveled bull Timebulleelaosed

Male Adult 20 4-montns-Male Adult 0 months Male Adult ~ 10 K Iday Male Male

Ae tlt Juvenilo

50 10

1 month days

Female Adult 63 2 weeks FemaleAul 32 1dy

25

+ 7 shy

-- -- ----shy

S-7-shy

1~~~77 7

gre 4b -L M D o e--ment pat nI -f nt xe rb-

X Ml~eaO pointrIEQENDno of raji mniord t13

Table lb Movement of radiom-monitored rats

Distance Distance from Sex ge traveled release site Time elapsed

(in (i )

Male Adult 30 30 6 hours

Mae Adlt 4+5 445 3 hours 40 10 3 hours 50 22 6 hours 50 45 6hours 40 10 6 hours 10 -20r 2days

522 6 hours 32 20 6 hours

Female juvenile 5535 3 hours 3 30P 3 hours

10 6 hours

15 20 15

12 6

hours hours

Female J avonile 35 35 3 hours 25 60 3 hours 15 70 6 hours 25 50 6 hours 230 2 days 25 55 6 hours 7C 83 iay

Feme Adult 80 80 3 hou s Adult- 3 0ota

Fonale Adult 330 i 30 3hDo

20 50 3 hours

4 40

z

1540

045 -shy70

07

6 hoirs 12 hors 6 hours+6 co=

27

Disregarding the t ime element the-average deParture o f marke

rats from their site of release was 2667 and 3875meters during the

wetand dry seasons respectively Radio-monitored rats had an average

of 4 0 18-meter departure from site of release From the point of

release juveniles ranged 10-83 meters adult males ranged 10-52

meters and adult females ranged 30-80 meters

Flash floods brought about by heavy rains weeding harvesting

and land preparation did not displace the rats to groat extent

similar to the findings of LaVoie et al (1971) Maximum departure

from point of release as disclosed by the recapture data under these

conditions was only 63 meters Likewise some rats remained within

50 metors from point of release for as long as four months Rats may

live long in their established home ranges and may not be immediately

displaced by usual farm activities without incorporating control

Population densities Tables 2a and 2b show the rocapture data

along with the monthly trap indices over the entire study period

Listed in Tables 3a and 3b are the population densities and

variances as estimated-by different models

Table 2a Wet soason recapture data

-Month--Tra Index Sa epte Mot T dReocapture Crop Stage

Same period Others rFxm activity

September 326 0 0 Transplanting

October 294 0 0 Booting

November 222 0 0 Mturity

December 403 0 0 Area cleared

January 32 0 1 2 Land preparatiot

February 2 0 0 Transplanting

Table 2b Dry season recapturo data

RIndex Crop Stage )ame period Others Farm activity

Month Tra Rocapture

ro-bootingMr3h 0 re1

Boot ing

April 1 0 0 WoedingMatlritj

My 47 1 1 rvest-ig

June 50 A K30 havst

L -

29

Table 3a Monthly wet season densities as estimated by the Petersen method

th Densitya Variance

October 132 7260 November 30 50820 December 1824 66100 January 1020 24400 February 693 213444

aaBasedon tho cumulative total number of marked animalssince Sbptemoer-

Table 3b Monthly dryseason densities as determined by difforent models based onthe capture-release-recapturo technique

ModelHayne Jolly Peterson Month NN se N 0-e

March 25 a 671a 15

Aprla a a a

May 160 55b 732 2 4 90

340d j1832d

aInsufficient data model not applicabl

becapture within bhe same month are exciuded

0Based on tne number of tagged animals atarting from tho trappingto which the recapture animal belonged

-dB6sdon the zotal number of animals Lagged archwine

30

L enunat te requenyof recapturesre ti6 to th total number of tagged individuals affects the precision of the est imates (Table 3b) -The Petersen and iiayne estimates cre ss preciso(seb 11832) _when based on the cumulative total numbor ofanimals

tagged since the first trapping period than When based on the total number tagged from the trapping period to which the recaptured animal belonged (se 490) moreAs tagged animals are released during the first period and few are recaptured during the next period the Petersen and Hayne Models tend toovrestimato the population size or

if they ever come close to the true value the confidence intervals are-widely spread On the other hand the Jolly model tends tounderestimate the population size (N 55 se = 735) as comped

to Petersens (N = 120 490)se and to hynes ( N- 160) when based on very ew recaptures few samples and low trap indices

(Table 2b) Dilution rates incnrporated in the Jolly model also cannot be determined due to insuffici-nt recaptoxe data

The effeotive census areas (MacLulich 1951) wore 99 sq ]m and 28548 sq m for the wet and dry seasons respectively Based on

thschanguP J11 population densities per heutarLampIert3ustitnttd using the Petersen method an( presented in Figure5 Poolaticn sizes were higher in the weL season than in tho Cy season I oth seasps density increased tward the matrity of the crop From Novjaber to

early Decembar (wet-Sea on) thec3 fields wplusmnih t m2tlkgfw wezo abandonedby +hp farmtirs -Dring this t it the ric plantsin

the studyr are andits v InItyi most ttally damagod abs

31

2000

1900

1800p

900

- I 800

a o 700

600

P40

3004

2001

100]

Oct Nov ~Dee Jan F-qb - Ar ipril a

Ionth

~Figure 5 MonthlyV population ctenpity pur hec bae

Wed s likewise filled the remaining -spaces inside the -paddies and on

the dikes The resiulting increase in covor and food supl ma hve favored anot increase in population sizeThis could aloexplain the

populatioi build up in November which became evident in the laer-pa2t

of December

It was noted that the proportion of males in the monthly samples

was negat ively correlated with poptilation1levol Cr=-87) No

sBignificantcorrelation Was- found-between population density and the proportion of juveniles in the samples

Trappabilitv Table 4 shows a very low dry season probability of survival of marked animalswithin the stadygrid (r=022) This Could mean that for every100marked rats roughl o lytormained

inside the grid for-the next months trappi g period therest ether

died or moved outside the study axea-

Table 4 Diy season population parajotos estimated by Jollys4tochastiedc modejl

Month N V(N)

-March-April 022 414

My 55

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

25

+ 7 shy

-- -- ----shy

S-7-shy

1~~~77 7

gre 4b -L M D o e--ment pat nI -f nt xe rb-

X Ml~eaO pointrIEQENDno of raji mniord t13

Table lb Movement of radiom-monitored rats

Distance Distance from Sex ge traveled release site Time elapsed

(in (i )

Male Adult 30 30 6 hours

Mae Adlt 4+5 445 3 hours 40 10 3 hours 50 22 6 hours 50 45 6hours 40 10 6 hours 10 -20r 2days

522 6 hours 32 20 6 hours

Female juvenile 5535 3 hours 3 30P 3 hours

10 6 hours

15 20 15

12 6

hours hours

Female J avonile 35 35 3 hours 25 60 3 hours 15 70 6 hours 25 50 6 hours 230 2 days 25 55 6 hours 7C 83 iay

Feme Adult 80 80 3 hou s Adult- 3 0ota

Fonale Adult 330 i 30 3hDo

20 50 3 hours

4 40

z

1540

045 -shy70

07

6 hoirs 12 hors 6 hours+6 co=

27

Disregarding the t ime element the-average deParture o f marke

rats from their site of release was 2667 and 3875meters during the

wetand dry seasons respectively Radio-monitored rats had an average

of 4 0 18-meter departure from site of release From the point of

release juveniles ranged 10-83 meters adult males ranged 10-52

meters and adult females ranged 30-80 meters

Flash floods brought about by heavy rains weeding harvesting

and land preparation did not displace the rats to groat extent

similar to the findings of LaVoie et al (1971) Maximum departure

from point of release as disclosed by the recapture data under these

conditions was only 63 meters Likewise some rats remained within

50 metors from point of release for as long as four months Rats may

live long in their established home ranges and may not be immediately

displaced by usual farm activities without incorporating control

Population densities Tables 2a and 2b show the rocapture data

along with the monthly trap indices over the entire study period

Listed in Tables 3a and 3b are the population densities and

variances as estimated-by different models

Table 2a Wet soason recapture data

-Month--Tra Index Sa epte Mot T dReocapture Crop Stage

Same period Others rFxm activity

September 326 0 0 Transplanting

October 294 0 0 Booting

November 222 0 0 Mturity

December 403 0 0 Area cleared

January 32 0 1 2 Land preparatiot

February 2 0 0 Transplanting

Table 2b Dry season recapturo data

RIndex Crop Stage )ame period Others Farm activity

Month Tra Rocapture

ro-bootingMr3h 0 re1

Boot ing

April 1 0 0 WoedingMatlritj

My 47 1 1 rvest-ig

June 50 A K30 havst

L -

29

Table 3a Monthly wet season densities as estimated by the Petersen method

th Densitya Variance

October 132 7260 November 30 50820 December 1824 66100 January 1020 24400 February 693 213444

aaBasedon tho cumulative total number of marked animalssince Sbptemoer-

Table 3b Monthly dryseason densities as determined by difforent models based onthe capture-release-recapturo technique

ModelHayne Jolly Peterson Month NN se N 0-e

March 25 a 671a 15

Aprla a a a

May 160 55b 732 2 4 90

340d j1832d

aInsufficient data model not applicabl

becapture within bhe same month are exciuded

0Based on tne number of tagged animals atarting from tho trappingto which the recapture animal belonged

-dB6sdon the zotal number of animals Lagged archwine

30

L enunat te requenyof recapturesre ti6 to th total number of tagged individuals affects the precision of the est imates (Table 3b) -The Petersen and iiayne estimates cre ss preciso(seb 11832) _when based on the cumulative total numbor ofanimals

tagged since the first trapping period than When based on the total number tagged from the trapping period to which the recaptured animal belonged (se 490) moreAs tagged animals are released during the first period and few are recaptured during the next period the Petersen and Hayne Models tend toovrestimato the population size or

if they ever come close to the true value the confidence intervals are-widely spread On the other hand the Jolly model tends tounderestimate the population size (N 55 se = 735) as comped

to Petersens (N = 120 490)se and to hynes ( N- 160) when based on very ew recaptures few samples and low trap indices

(Table 2b) Dilution rates incnrporated in the Jolly model also cannot be determined due to insuffici-nt recaptoxe data

The effeotive census areas (MacLulich 1951) wore 99 sq ]m and 28548 sq m for the wet and dry seasons respectively Based on

thschanguP J11 population densities per heutarLampIert3ustitnttd using the Petersen method an( presented in Figure5 Poolaticn sizes were higher in the weL season than in tho Cy season I oth seasps density increased tward the matrity of the crop From Novjaber to

early Decembar (wet-Sea on) thec3 fields wplusmnih t m2tlkgfw wezo abandonedby +hp farmtirs -Dring this t it the ric plantsin

the studyr are andits v InItyi most ttally damagod abs

31

2000

1900

1800p

900

- I 800

a o 700

600

P40

3004

2001

100]

Oct Nov ~Dee Jan F-qb - Ar ipril a

Ionth

~Figure 5 MonthlyV population ctenpity pur hec bae

Wed s likewise filled the remaining -spaces inside the -paddies and on

the dikes The resiulting increase in covor and food supl ma hve favored anot increase in population sizeThis could aloexplain the

populatioi build up in November which became evident in the laer-pa2t

of December

It was noted that the proportion of males in the monthly samples

was negat ively correlated with poptilation1levol Cr=-87) No

sBignificantcorrelation Was- found-between population density and the proportion of juveniles in the samples

Trappabilitv Table 4 shows a very low dry season probability of survival of marked animalswithin the stadygrid (r=022) This Could mean that for every100marked rats roughl o lytormained

inside the grid for-the next months trappi g period therest ether

died or moved outside the study axea-

Table 4 Diy season population parajotos estimated by Jollys4tochastiedc modejl

Month N V(N)

-March-April 022 414

My 55

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

Table lb Movement of radiom-monitored rats

Distance Distance from Sex ge traveled release site Time elapsed

(in (i )

Male Adult 30 30 6 hours

Mae Adlt 4+5 445 3 hours 40 10 3 hours 50 22 6 hours 50 45 6hours 40 10 6 hours 10 -20r 2days

522 6 hours 32 20 6 hours

Female juvenile 5535 3 hours 3 30P 3 hours

10 6 hours

15 20 15

12 6

hours hours

Female J avonile 35 35 3 hours 25 60 3 hours 15 70 6 hours 25 50 6 hours 230 2 days 25 55 6 hours 7C 83 iay

Feme Adult 80 80 3 hou s Adult- 3 0ota

Fonale Adult 330 i 30 3hDo

20 50 3 hours

4 40

z

1540

045 -shy70

07

6 hoirs 12 hors 6 hours+6 co=

27

Disregarding the t ime element the-average deParture o f marke

rats from their site of release was 2667 and 3875meters during the

wetand dry seasons respectively Radio-monitored rats had an average

of 4 0 18-meter departure from site of release From the point of

release juveniles ranged 10-83 meters adult males ranged 10-52

meters and adult females ranged 30-80 meters

Flash floods brought about by heavy rains weeding harvesting

and land preparation did not displace the rats to groat extent

similar to the findings of LaVoie et al (1971) Maximum departure

from point of release as disclosed by the recapture data under these

conditions was only 63 meters Likewise some rats remained within

50 metors from point of release for as long as four months Rats may

live long in their established home ranges and may not be immediately

displaced by usual farm activities without incorporating control

Population densities Tables 2a and 2b show the rocapture data

along with the monthly trap indices over the entire study period

Listed in Tables 3a and 3b are the population densities and

variances as estimated-by different models

Table 2a Wet soason recapture data

-Month--Tra Index Sa epte Mot T dReocapture Crop Stage

Same period Others rFxm activity

September 326 0 0 Transplanting

October 294 0 0 Booting

November 222 0 0 Mturity

December 403 0 0 Area cleared

January 32 0 1 2 Land preparatiot

February 2 0 0 Transplanting

Table 2b Dry season recapturo data

RIndex Crop Stage )ame period Others Farm activity

Month Tra Rocapture

ro-bootingMr3h 0 re1

Boot ing

April 1 0 0 WoedingMatlritj

My 47 1 1 rvest-ig

June 50 A K30 havst

L -

29

Table 3a Monthly wet season densities as estimated by the Petersen method

th Densitya Variance

October 132 7260 November 30 50820 December 1824 66100 January 1020 24400 February 693 213444

aaBasedon tho cumulative total number of marked animalssince Sbptemoer-

Table 3b Monthly dryseason densities as determined by difforent models based onthe capture-release-recapturo technique

ModelHayne Jolly Peterson Month NN se N 0-e

March 25 a 671a 15

Aprla a a a

May 160 55b 732 2 4 90

340d j1832d

aInsufficient data model not applicabl

becapture within bhe same month are exciuded

0Based on tne number of tagged animals atarting from tho trappingto which the recapture animal belonged

-dB6sdon the zotal number of animals Lagged archwine

30

L enunat te requenyof recapturesre ti6 to th total number of tagged individuals affects the precision of the est imates (Table 3b) -The Petersen and iiayne estimates cre ss preciso(seb 11832) _when based on the cumulative total numbor ofanimals

tagged since the first trapping period than When based on the total number tagged from the trapping period to which the recaptured animal belonged (se 490) moreAs tagged animals are released during the first period and few are recaptured during the next period the Petersen and Hayne Models tend toovrestimato the population size or

if they ever come close to the true value the confidence intervals are-widely spread On the other hand the Jolly model tends tounderestimate the population size (N 55 se = 735) as comped

to Petersens (N = 120 490)se and to hynes ( N- 160) when based on very ew recaptures few samples and low trap indices

(Table 2b) Dilution rates incnrporated in the Jolly model also cannot be determined due to insuffici-nt recaptoxe data

The effeotive census areas (MacLulich 1951) wore 99 sq ]m and 28548 sq m for the wet and dry seasons respectively Based on

thschanguP J11 population densities per heutarLampIert3ustitnttd using the Petersen method an( presented in Figure5 Poolaticn sizes were higher in the weL season than in tho Cy season I oth seasps density increased tward the matrity of the crop From Novjaber to

early Decembar (wet-Sea on) thec3 fields wplusmnih t m2tlkgfw wezo abandonedby +hp farmtirs -Dring this t it the ric plantsin

the studyr are andits v InItyi most ttally damagod abs

31

2000

1900

1800p

900

- I 800

a o 700

600

P40

3004

2001

100]

Oct Nov ~Dee Jan F-qb - Ar ipril a

Ionth

~Figure 5 MonthlyV population ctenpity pur hec bae

Wed s likewise filled the remaining -spaces inside the -paddies and on

the dikes The resiulting increase in covor and food supl ma hve favored anot increase in population sizeThis could aloexplain the

populatioi build up in November which became evident in the laer-pa2t

of December

It was noted that the proportion of males in the monthly samples

was negat ively correlated with poptilation1levol Cr=-87) No

sBignificantcorrelation Was- found-between population density and the proportion of juveniles in the samples

Trappabilitv Table 4 shows a very low dry season probability of survival of marked animalswithin the stadygrid (r=022) This Could mean that for every100marked rats roughl o lytormained

inside the grid for-the next months trappi g period therest ether

died or moved outside the study axea-

Table 4 Diy season population parajotos estimated by Jollys4tochastiedc modejl

Month N V(N)

-March-April 022 414

My 55

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

27

Disregarding the t ime element the-average deParture o f marke

rats from their site of release was 2667 and 3875meters during the

wetand dry seasons respectively Radio-monitored rats had an average

of 4 0 18-meter departure from site of release From the point of

release juveniles ranged 10-83 meters adult males ranged 10-52

meters and adult females ranged 30-80 meters

Flash floods brought about by heavy rains weeding harvesting

and land preparation did not displace the rats to groat extent

similar to the findings of LaVoie et al (1971) Maximum departure

from point of release as disclosed by the recapture data under these

conditions was only 63 meters Likewise some rats remained within

50 metors from point of release for as long as four months Rats may

live long in their established home ranges and may not be immediately

displaced by usual farm activities without incorporating control

Population densities Tables 2a and 2b show the rocapture data

along with the monthly trap indices over the entire study period

Listed in Tables 3a and 3b are the population densities and

variances as estimated-by different models

Table 2a Wet soason recapture data

-Month--Tra Index Sa epte Mot T dReocapture Crop Stage

Same period Others rFxm activity

September 326 0 0 Transplanting

October 294 0 0 Booting

November 222 0 0 Mturity

December 403 0 0 Area cleared

January 32 0 1 2 Land preparatiot

February 2 0 0 Transplanting

Table 2b Dry season recapturo data

RIndex Crop Stage )ame period Others Farm activity

Month Tra Rocapture

ro-bootingMr3h 0 re1

Boot ing

April 1 0 0 WoedingMatlritj

My 47 1 1 rvest-ig

June 50 A K30 havst

L -

29

Table 3a Monthly wet season densities as estimated by the Petersen method

th Densitya Variance

October 132 7260 November 30 50820 December 1824 66100 January 1020 24400 February 693 213444

aaBasedon tho cumulative total number of marked animalssince Sbptemoer-

Table 3b Monthly dryseason densities as determined by difforent models based onthe capture-release-recapturo technique

ModelHayne Jolly Peterson Month NN se N 0-e

March 25 a 671a 15

Aprla a a a

May 160 55b 732 2 4 90

340d j1832d

aInsufficient data model not applicabl

becapture within bhe same month are exciuded

0Based on tne number of tagged animals atarting from tho trappingto which the recapture animal belonged

-dB6sdon the zotal number of animals Lagged archwine

30

L enunat te requenyof recapturesre ti6 to th total number of tagged individuals affects the precision of the est imates (Table 3b) -The Petersen and iiayne estimates cre ss preciso(seb 11832) _when based on the cumulative total numbor ofanimals

tagged since the first trapping period than When based on the total number tagged from the trapping period to which the recaptured animal belonged (se 490) moreAs tagged animals are released during the first period and few are recaptured during the next period the Petersen and Hayne Models tend toovrestimato the population size or

if they ever come close to the true value the confidence intervals are-widely spread On the other hand the Jolly model tends tounderestimate the population size (N 55 se = 735) as comped

to Petersens (N = 120 490)se and to hynes ( N- 160) when based on very ew recaptures few samples and low trap indices

(Table 2b) Dilution rates incnrporated in the Jolly model also cannot be determined due to insuffici-nt recaptoxe data

The effeotive census areas (MacLulich 1951) wore 99 sq ]m and 28548 sq m for the wet and dry seasons respectively Based on

thschanguP J11 population densities per heutarLampIert3ustitnttd using the Petersen method an( presented in Figure5 Poolaticn sizes were higher in the weL season than in tho Cy season I oth seasps density increased tward the matrity of the crop From Novjaber to

early Decembar (wet-Sea on) thec3 fields wplusmnih t m2tlkgfw wezo abandonedby +hp farmtirs -Dring this t it the ric plantsin

the studyr are andits v InItyi most ttally damagod abs

31

2000

1900

1800p

900

- I 800

a o 700

600

P40

3004

2001

100]

Oct Nov ~Dee Jan F-qb - Ar ipril a

Ionth

~Figure 5 MonthlyV population ctenpity pur hec bae

Wed s likewise filled the remaining -spaces inside the -paddies and on

the dikes The resiulting increase in covor and food supl ma hve favored anot increase in population sizeThis could aloexplain the

populatioi build up in November which became evident in the laer-pa2t

of December

It was noted that the proportion of males in the monthly samples

was negat ively correlated with poptilation1levol Cr=-87) No

sBignificantcorrelation Was- found-between population density and the proportion of juveniles in the samples

Trappabilitv Table 4 shows a very low dry season probability of survival of marked animalswithin the stadygrid (r=022) This Could mean that for every100marked rats roughl o lytormained

inside the grid for-the next months trappi g period therest ether

died or moved outside the study axea-

Table 4 Diy season population parajotos estimated by Jollys4tochastiedc modejl

Month N V(N)

-March-April 022 414

My 55

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

Table 2a Wet soason recapture data

-Month--Tra Index Sa epte Mot T dReocapture Crop Stage

Same period Others rFxm activity

September 326 0 0 Transplanting

October 294 0 0 Booting

November 222 0 0 Mturity

December 403 0 0 Area cleared

January 32 0 1 2 Land preparatiot

February 2 0 0 Transplanting

Table 2b Dry season recapturo data

RIndex Crop Stage )ame period Others Farm activity

Month Tra Rocapture

ro-bootingMr3h 0 re1

Boot ing

April 1 0 0 WoedingMatlritj

My 47 1 1 rvest-ig

June 50 A K30 havst

L -

29

Table 3a Monthly wet season densities as estimated by the Petersen method

th Densitya Variance

October 132 7260 November 30 50820 December 1824 66100 January 1020 24400 February 693 213444

aaBasedon tho cumulative total number of marked animalssince Sbptemoer-

Table 3b Monthly dryseason densities as determined by difforent models based onthe capture-release-recapturo technique

ModelHayne Jolly Peterson Month NN se N 0-e

March 25 a 671a 15

Aprla a a a

May 160 55b 732 2 4 90

340d j1832d

aInsufficient data model not applicabl

becapture within bhe same month are exciuded

0Based on tne number of tagged animals atarting from tho trappingto which the recapture animal belonged

-dB6sdon the zotal number of animals Lagged archwine

30

L enunat te requenyof recapturesre ti6 to th total number of tagged individuals affects the precision of the est imates (Table 3b) -The Petersen and iiayne estimates cre ss preciso(seb 11832) _when based on the cumulative total numbor ofanimals

tagged since the first trapping period than When based on the total number tagged from the trapping period to which the recaptured animal belonged (se 490) moreAs tagged animals are released during the first period and few are recaptured during the next period the Petersen and Hayne Models tend toovrestimato the population size or

if they ever come close to the true value the confidence intervals are-widely spread On the other hand the Jolly model tends tounderestimate the population size (N 55 se = 735) as comped

to Petersens (N = 120 490)se and to hynes ( N- 160) when based on very ew recaptures few samples and low trap indices

(Table 2b) Dilution rates incnrporated in the Jolly model also cannot be determined due to insuffici-nt recaptoxe data

The effeotive census areas (MacLulich 1951) wore 99 sq ]m and 28548 sq m for the wet and dry seasons respectively Based on

thschanguP J11 population densities per heutarLampIert3ustitnttd using the Petersen method an( presented in Figure5 Poolaticn sizes were higher in the weL season than in tho Cy season I oth seasps density increased tward the matrity of the crop From Novjaber to

early Decembar (wet-Sea on) thec3 fields wplusmnih t m2tlkgfw wezo abandonedby +hp farmtirs -Dring this t it the ric plantsin

the studyr are andits v InItyi most ttally damagod abs

31

2000

1900

1800p

900

- I 800

a o 700

600

P40

3004

2001

100]

Oct Nov ~Dee Jan F-qb - Ar ipril a

Ionth

~Figure 5 MonthlyV population ctenpity pur hec bae

Wed s likewise filled the remaining -spaces inside the -paddies and on

the dikes The resiulting increase in covor and food supl ma hve favored anot increase in population sizeThis could aloexplain the

populatioi build up in November which became evident in the laer-pa2t

of December

It was noted that the proportion of males in the monthly samples

was negat ively correlated with poptilation1levol Cr=-87) No

sBignificantcorrelation Was- found-between population density and the proportion of juveniles in the samples

Trappabilitv Table 4 shows a very low dry season probability of survival of marked animalswithin the stadygrid (r=022) This Could mean that for every100marked rats roughl o lytormained

inside the grid for-the next months trappi g period therest ether

died or moved outside the study axea-

Table 4 Diy season population parajotos estimated by Jollys4tochastiedc modejl

Month N V(N)

-March-April 022 414

My 55

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

29

Table 3a Monthly wet season densities as estimated by the Petersen method

th Densitya Variance

October 132 7260 November 30 50820 December 1824 66100 January 1020 24400 February 693 213444

aaBasedon tho cumulative total number of marked animalssince Sbptemoer-

Table 3b Monthly dryseason densities as determined by difforent models based onthe capture-release-recapturo technique

ModelHayne Jolly Peterson Month NN se N 0-e

March 25 a 671a 15

Aprla a a a

May 160 55b 732 2 4 90

340d j1832d

aInsufficient data model not applicabl

becapture within bhe same month are exciuded

0Based on tne number of tagged animals atarting from tho trappingto which the recapture animal belonged

-dB6sdon the zotal number of animals Lagged archwine

30

L enunat te requenyof recapturesre ti6 to th total number of tagged individuals affects the precision of the est imates (Table 3b) -The Petersen and iiayne estimates cre ss preciso(seb 11832) _when based on the cumulative total numbor ofanimals

tagged since the first trapping period than When based on the total number tagged from the trapping period to which the recaptured animal belonged (se 490) moreAs tagged animals are released during the first period and few are recaptured during the next period the Petersen and Hayne Models tend toovrestimato the population size or

if they ever come close to the true value the confidence intervals are-widely spread On the other hand the Jolly model tends tounderestimate the population size (N 55 se = 735) as comped

to Petersens (N = 120 490)se and to hynes ( N- 160) when based on very ew recaptures few samples and low trap indices

(Table 2b) Dilution rates incnrporated in the Jolly model also cannot be determined due to insuffici-nt recaptoxe data

The effeotive census areas (MacLulich 1951) wore 99 sq ]m and 28548 sq m for the wet and dry seasons respectively Based on

thschanguP J11 population densities per heutarLampIert3ustitnttd using the Petersen method an( presented in Figure5 Poolaticn sizes were higher in the weL season than in tho Cy season I oth seasps density increased tward the matrity of the crop From Novjaber to

early Decembar (wet-Sea on) thec3 fields wplusmnih t m2tlkgfw wezo abandonedby +hp farmtirs -Dring this t it the ric plantsin

the studyr are andits v InItyi most ttally damagod abs

31

2000

1900

1800p

900

- I 800

a o 700

600

P40

3004

2001

100]

Oct Nov ~Dee Jan F-qb - Ar ipril a

Ionth

~Figure 5 MonthlyV population ctenpity pur hec bae

Wed s likewise filled the remaining -spaces inside the -paddies and on

the dikes The resiulting increase in covor and food supl ma hve favored anot increase in population sizeThis could aloexplain the

populatioi build up in November which became evident in the laer-pa2t

of December

It was noted that the proportion of males in the monthly samples

was negat ively correlated with poptilation1levol Cr=-87) No

sBignificantcorrelation Was- found-between population density and the proportion of juveniles in the samples

Trappabilitv Table 4 shows a very low dry season probability of survival of marked animalswithin the stadygrid (r=022) This Could mean that for every100marked rats roughl o lytormained

inside the grid for-the next months trappi g period therest ether

died or moved outside the study axea-

Table 4 Diy season population parajotos estimated by Jollys4tochastiedc modejl

Month N V(N)

-March-April 022 414

My 55

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

30

L enunat te requenyof recapturesre ti6 to th total number of tagged individuals affects the precision of the est imates (Table 3b) -The Petersen and iiayne estimates cre ss preciso(seb 11832) _when based on the cumulative total numbor ofanimals

tagged since the first trapping period than When based on the total number tagged from the trapping period to which the recaptured animal belonged (se 490) moreAs tagged animals are released during the first period and few are recaptured during the next period the Petersen and Hayne Models tend toovrestimato the population size or

if they ever come close to the true value the confidence intervals are-widely spread On the other hand the Jolly model tends tounderestimate the population size (N 55 se = 735) as comped

to Petersens (N = 120 490)se and to hynes ( N- 160) when based on very ew recaptures few samples and low trap indices

(Table 2b) Dilution rates incnrporated in the Jolly model also cannot be determined due to insuffici-nt recaptoxe data

The effeotive census areas (MacLulich 1951) wore 99 sq ]m and 28548 sq m for the wet and dry seasons respectively Based on

thschanguP J11 population densities per heutarLampIert3ustitnttd using the Petersen method an( presented in Figure5 Poolaticn sizes were higher in the weL season than in tho Cy season I oth seasps density increased tward the matrity of the crop From Novjaber to

early Decembar (wet-Sea on) thec3 fields wplusmnih t m2tlkgfw wezo abandonedby +hp farmtirs -Dring this t it the ric plantsin

the studyr are andits v InItyi most ttally damagod abs

31

2000

1900

1800p

900

- I 800

a o 700

600

P40

3004

2001

100]

Oct Nov ~Dee Jan F-qb - Ar ipril a

Ionth

~Figure 5 MonthlyV population ctenpity pur hec bae

Wed s likewise filled the remaining -spaces inside the -paddies and on

the dikes The resiulting increase in covor and food supl ma hve favored anot increase in population sizeThis could aloexplain the

populatioi build up in November which became evident in the laer-pa2t

of December

It was noted that the proportion of males in the monthly samples

was negat ively correlated with poptilation1levol Cr=-87) No

sBignificantcorrelation Was- found-between population density and the proportion of juveniles in the samples

Trappabilitv Table 4 shows a very low dry season probability of survival of marked animalswithin the stadygrid (r=022) This Could mean that for every100marked rats roughl o lytormained

inside the grid for-the next months trappi g period therest ether

died or moved outside the study axea-

Table 4 Diy season population parajotos estimated by Jollys4tochastiedc modejl

Month N V(N)

-March-April 022 414

My 55

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

31

2000

1900

1800p

900

- I 800

a o 700

600

P40

3004

2001

100]

Oct Nov ~Dee Jan F-qb - Ar ipril a

Ionth

~Figure 5 MonthlyV population ctenpity pur hec bae

Wed s likewise filled the remaining -spaces inside the -paddies and on

the dikes The resiulting increase in covor and food supl ma hve favored anot increase in population sizeThis could aloexplain the

populatioi build up in November which became evident in the laer-pa2t

of December

It was noted that the proportion of males in the monthly samples

was negat ively correlated with poptilation1levol Cr=-87) No

sBignificantcorrelation Was- found-between population density and the proportion of juveniles in the samples

Trappabilitv Table 4 shows a very low dry season probability of survival of marked animalswithin the stadygrid (r=022) This Could mean that for every100marked rats roughl o lytormained

inside the grid for-the next months trappi g period therest ether

died or moved outside the study axea-

Table 4 Diy season population parajotos estimated by Jollys4tochastiedc modejl

Month N V(N)

-March-April 022 414

My 55

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

Wed s likewise filled the remaining -spaces inside the -paddies and on

the dikes The resiulting increase in covor and food supl ma hve favored anot increase in population sizeThis could aloexplain the

populatioi build up in November which became evident in the laer-pa2t

of December

It was noted that the proportion of males in the monthly samples

was negat ively correlated with poptilation1levol Cr=-87) No

sBignificantcorrelation Was- found-between population density and the proportion of juveniles in the samples

Trappabilitv Table 4 shows a very low dry season probability of survival of marked animalswithin the stadygrid (r=022) This Could mean that for every100marked rats roughl o lytormained

inside the grid for-the next months trappi g period therest ether

died or moved outside the study axea-

Table 4 Diy season population parajotos estimated by Jollys4tochastiedc modejl

Month N V(N)

-March-April 022 414

My 55

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

33T() could alsexplain mathematically the ow

recaptures under the following goditio

a Equal probability of capture of marked -and_ unmarko danimals b~Low tr4pability (159 0 percent during th dry seso)

c Relatively uniformsurvival rates throughout the study perio chances of survival of marked-and unmar ked animals being qual and

d The populatfon is highly mobile

Under the- first two conditions mentioned tho chance of

-rcapturling the marked animal is greatly reduced During the dry season study only 2-5 rats were caught on the average for very 100 available traps (Table 2b) Since only 2 out of every 300 marked rats stay for the next monthts trapping period(Taho ) chances are the

2-5 rats caught per 100 ava lablw traps are all unmarked The third cOonditionis one assumption of moct capturerelaese-recapture mthods while the last conditionis sggeosted by themovement Mdhome range

data

The rate of recapture likeuise was inverscly pronortional to he available food supply and the amount of plant cover as can bo

refetedfrom Tables 2a and 2b All recaiarc- were madi onharvest

up to the prebotting satage tf the next crop when those factors were iTW FPombooilng toward maturity-and whil the fields remlned

irrigatced thren daplenty offood in osupply orrip-ofth nails lnsecto Indevon waodo which mayhave aompeted -with tho baltamp in-Uhe trapsl Th s could acunt or fihe low trapping SL~cesses (294

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

34

vad 222 percent during the wet season 15 and 41 percent during the

dryseason) and subsequently few or no recaptures during these per3ods SThose findings are in agreemont with those reported by Swink et al

(1969) in Central Luzon and Sanchez et al (1971) in Siniloaneir Lagunatagged64 e ent of

Swinket al (1969) recaptured over half l perc

-animalsduring the height of the dryseason when food and coverwer

at a minimnu Sanchez --at (pl)hada low trap indox (792 porcont)

at bootingbullt and gradually increaied toward land preparatibn for

thenext crop

The-0iocapture problem may also be traced todifferences in

individual b6havioriofmarked aninals -As can be seen from Tables 2a

and 2b three rats were captured marked and recaptured in just one

trapping eriod while four to were marked in one periodand

recaptured only in later trappings This implies that some rats may

tend to be taphappyor trapshy more tan others i] mci take only

one to re6apture traphappy ratand as 2ong astre in longershyday a

thn foau- months to recover a trapshy rat (Table la) -t e~n th e o t

TrappbiJity is likadse influenced by the reoponse of rab- to

thetrapsplocation o6f the traps as sh)wn in Figura 6 hec4teaso-6 rerve AtrhagAithoc)

Of the grid was clos t the imaginary center of activity most of

the Catches taere made )n the southwicsthorh pcrtiDlon of the grid SOrnO

trapsespec ily ontno deeoly sabmorgod eaotern porzion L thegr

dd not ha tc brghout the study This i0decte that

to re trap~ traps boVeseem preeato s aet in higher grov t SehN

deep irrigaticn watur

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

i

I i~

a

-

j i1 i

j

I

-

2 1

1

lt

12-

7

2

2

4

2

__a

2

1

1

2

-

bull

722

LEGM~D~

)C-

d edG 0 t-on of rid

Gente of grid

Traptrap -shy-

I

-

-

6 L~srhi~o o atgwi at ampuong tzp~ et in grd6

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

Setting more traps ingrId Inside the paddies did not imuprove recaptuxre data althoughthe frequency of recapture was better distributed Trapsuccess was generallyhigher when traps Wore set along the dikes during wet seanthan when traps were sotinside the

paddies duri the dryseason Likewise in the dry season grid trap

success was highor among traps sot within25 meters from the nearest

dikei(502 percent) than among traps setmoro than25 moters from the nearest dike (312 percent)

Trap success asquito variable-evenwithin thesamo trapping period Gnerally more ats were caught during overcast and rainy

nights than-n clear and moonlit nithts

OaDtre-release-rocaoture tochnqco a case study This study was conducted not only to estimate population parameters but also to set-so guidelinos for future works along this line In general the

aiiiormation obtained in the pIlesent work is much loss than expected

and the concluions based on thelimito2 obsorvatiDns rcmain to be

verified dt is hoped that a simpl-and objective case Study of th merito and dst Of tiswork would be of help to oter researchers

The difficulties encoLntorod in this study approximated those

roportod by 0avisa(g3)pioblo was 0lecticn0no tha of a fairly

horogenuous area which approximctely coinc dej with tia home ranges

dfthe animals and suLch that rio traps wou 14 be set Li obviously

unfavrable location This roblem was not successfully vorome n i ptIn454 t6 wer is otyadair part oh t Vd t otas eL ap e t oMdost cnbullto

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

areasThesebordering areas must haVe contributed some extraneous

factors whose individual effects could not be distinguished In the latter part not all paddies included in the grid were planted at the same time Likow se the fields were not equally flooded due to poor drainage particularly on the easternportion of the field

Related to this problem was the great time Llnd effort spent in

laying out the grid setting the traps and data collection espeoially in the deeply flooded portions of the field It took 14 man-hours to stake the 34 x 14 grid inside the paddies another 4 man-hours to set

the 196 live traps and 3 man-hours to collect the data More man-houtr and care were required during the reproductive stage s of the crop Also propor arrangement have to be made with the landowners and tenants especially towards maturity of the crop

It is stggested that a uniform study Plot hn ehoaon cb I(shy100meters from rough areas Blair (1941) recommendcd a study plot

101 0 times the expected home range of the species o

In his case the average home range of 2564 sq m hints the need for z uliform study area at least 160 m x 160 m or ita equivalent so as to include the othoruiez transients to a 130 m x 130m grid as useditr this st cr A larger plo will also provide more roliab]e data per trapping

Traps should be laid In grid pattera at samethe spaping l0m betweon traDs) if the problem men-ioned earlier re ro encountered

grid evenly distributesThe ho traps simplifies the ucalculations nl home ranges ad facilitate6 direot comparison 1dth similarlyk

conductodstudies Whene~ver this- isnot fasiOle the trapsi yb

38

i

set 10111apart along-the dikes of uniformnJy -Sized aind shaped paddies8 C

-sim study plot This system of laying trapsthe wet season

simulates a combination of different trap spacings recommended by

IKlkkawa (1964+) MaoLulioh (1951) and other investigators of home ranges

of different species

Traps should be checked timeand again for damage to prevent- animals from escaping numbered are bt- Z0Alo eartags ohi

ear punohng s9ie the holes may in time become indistinguishable from

irregular outs or damages along the margin of the ears Care should

likewise be exercised inhandling the animals to prevent shock and

possible death For bait it may be more convenient to use sweet

potato than fresh coconut Thus far this studhasyielded some information worth further

The capture-release~recapturetechnique may not be a practical

mothod for assessing-rodent populationo -density unlebs the problem

ofjfew recaptures is-solved On t he other hanid a change-ini-ratio

estimate might give a reliable index to population size based on the

observed negative corrolation between the proportion oC males in the

sample and population size A study aimcd at estimatin3 population

density should be planned such that two or morecounter-checking methods

are employed simultaneously For example the remva method may immediatoly follow the last data collectio for thentureeroloase-

recapture method or the two methods my alternate at some interval

time the change- in-ratio estimate may be used with the capture-releaseshy

9 recapture method by not-rtui t the populationratS caughti

certain tappig p ods so as to effect some change inpoplation composition Many possible combination of methods may be triedbut in anycaseavailability of resources should be considerod

Traps set in grid inside the paddies wore no better than traps setalong the dikes indetecting movements and home ranges of marked rats Improved teleometry and tagging techniques should give reliable data in this regard Inthe present study radio-monitored rats presented some problems such as difficulty inPinpointing the location of individuals especial]y at night weak signals and mixed radio receptions The tiniest lightest most powerful and most dw-4abi transistoriod radio transmitter has yet to be developed It isalso-vital that the rats fitted with telemetry devices be givenenough time to recover from the handling and the attaehmont of thu ofthe transmitter before movement data be collected Before

adjustment movement could possibly bo attributed to streso or

displacement behavior

Trappabilty upon which tho estimates of tho different parameters ara based is the result of the interaction ifscveral factors stated by Kickkwo 1964)as the onvironent ar d the chara tristlco of the L-4dividual as vill as thc population itself Unfrtwatelyp it is not easy to detent the sorato ffects Of eachfactor aid -onclude that the rrsult ie st im y th eun rc ach effect

4P

-AsKikkawa (1964) himself concluded

The standardization of a single method permitting the minimum expenditure of time and labor for maximum yieldof information on all aspects of a population is probably impossible Design of experiments and observations must be rado in accordance with the specific purpose of the study

In this connection a limited study may provide more meaningful

reslts than a broad one

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ANDERSON P K 1961 Density social structure and nonsocialenvironment in the house mouse populations and the implicationsfor regulations of numbers Trans D Y Acad Sci sor 2(23)47-451

ANDREWARTHA H G 1961 Introduction to the study of animal populations 281 p Chicago University of Chicago Press

and L C BIRCH 1954 The distribution andabundance of animals 782 p Chicago University of ChicagoPress

BAILEY N T J 1951 On estimating the size of mobile populationsfrom recapture data Biometrika 38 293-306

1952 Improvements in the interpretation ofrecapture data Jour knin Ecol 21 120-127

BLAIR W F 1940 Home ranges and population of the meadow volein Southern Michigan Jour lilrllf Mgt 4 i49-161

1951 Population structure social behavior andenvironmental relations in a nataral populatiLn of the beachmoase (Peromyspus polionotus leucocephalus) Ornntrib LabVert Biol University of Michigan 48- 1- 47

B0 B Py Jr 1939 The q adrat method of sudying small mammalpopulatiuns Sci Publ Cleveland Mas hat Hiat 5(4 15-77 BuRWW H 194U Territorial behavior and population of somesmall maramals in Southern hichigan Misc Publ Mus Z0al0

University of Michigan 45 3-58

913 Territoriality and home range conc~pts asapplied to mamnals Jour ammal 24 346-352

CIAPMAN D G 1955 Population estimation based on Thange ofcomposition caused by a selective remova Biomcrika 42 (3 and 4) 279-290

3 ROBSONad D i96 The analysis of atch curyeo B-lomtric3 16(3)i 354-368

42

CORMAK I M 1964 Estimates of survival hom the sighting of marked animals Biometrika 51 229-238

1966 A test for equalcatchability Biometrics 22(2) 330-342

1971 The logic of capture-recapturo ostimatosBiomotrics 27(1) 247

DMLE D D 1942 The cottaintail rabbits in Connecticut StateGeol and Nat Hist Surv Bull 65 1-97

DARROCH Js N 1958 The mltiple recapture census I Estimationof a closed population Biometrika 45 343-359

1959 The multiple recapture census IIEstimatiiwhen there is immigration or death Biomotrilca 48 336-351

1961 The two sample capture-recapture census whentagging and sampling are stratified Biometrika 48 241-260 DAVEUPORT L B Jr 1964 Structure of two PeroLscus polionotas

populations at the AEC Savannah Rivor Plant Jour Aammal 45 95-113

DAVIS DE 1953a Analysis of home ran-) from recaoturo data Jour Mammal 34 352-358

_ urRv 1953b The clhracteristics of rat pcpulations

Quart Rev Biol 28 373-401

1964 Manual for analysis of rodent populations-University Microfilms Ann Abor 82 p

J T EMEI nd A W STOKES 1948 Studius 3n hormo range inhown rat Jur Mammal 29 207-225

EBERRrDT T 0 1969 Population estimates from recapturefrequencies Jour 1ildlt Mgt 33(1) 28-39

EGOROV 0 V 1961 Forecasting thu numbor of squirroiC in YakutiyReferat Zh Biol (Moscow) No 30577 (WildI 1Wcl1Q02)

EMLEN J T A M STOKE aij D E 1949 DAVTIO 4etiods forestirniting populations uf brown rats n rXban ahbituo Ecoogy ) 4

EVANS F C and R HOLERIELD 1943 A population study of thebeechey ground squirrel in central California Jour Mammal 24i 231-260

FISHER R A and E B MDRD 1947 The spread of a gone in naturalconditions in a colony of the moth Panaxia domincla L Heredityils 143-174

FORMOZOV A N and Yu A ISAKOV (ed) 1967 Organization andmethods of censusing birds and harmful rodents (Translatedfrom Russian) U S Dept of Interior and Nat Sc FoundationWashington D 0 269 p

GETZ L L 1961 Homo ranges territoriality and movement of themeadow vole Jour Mammal 2 24-36

GRODZINSKI W ot al 1966 Estimation of rodent numbers by meansof prebaiting and intensive removal Acta Thoriol (Warsaw)11 297-314 (Biol Abstr 48 78977)

GUTIERREZ J S 1967 On the statistical problems of establishingeconomic measures of natural resources The Phil Statist 16(I and 2) 31-52

HANSON 1 R 1963 Calculation of productivity survival andabundance of selected vartebrates from sex and agu ratiosWildlf Monographo 9 60 p

HANSSON L 1967 Index lino catches as a basis of populationstudies on small animals Oikos (Sweden) 18 261276 (Biol Abstr 49 81826)

HAYNE D 949 Two methods for estimating populations fromtrapping recordo Jour Mxmal 30 39-411

HENRY C J W S OVERTON and H M WIGT 1970 Dothrtriningparameters for populations by using strucaral models Jourildlf Mgt 34(4) 690-703

JACKSON 1939 The aaalyjis of an anim-il population JqiAnim Ecl 8 238-246

1940 The analysis of a tsc-tse fly populationAnn Fugonis 10 32 1-3c9

S1944 The ann1ysito of a-tsn-tco poundlj PLpulationII Ann Eig)nies 12 17amp-205

_________ 198 h aayif a te-tse fly population III-Ann Eugenics 14 91-108

1JANION M et al 1968 Estimates of numbers of rodents with variable probability of capture Acta Theriol 1 285-294 (Wildlf Rov 134 24)

JOLLY G M 1963 Estimates of population parameters from multiple deterministic mode1recapture data with both death and dilution -

Biometrika 50(1 and 2) 113-126

1965 Explicit estimates from capture-recapture

data with both death and immigration - stochastic model

Biomtrika 52(1 and 2) 225-248

as a mcasure of probableJORGELSEN 0 D 1968 Home rango of small mammals Jour Mammalinteractions among populations

49(2) 104-112

K E 1961 A new method for measuring home ranges ofJUSTICE small mammals Jour Mammal 42(4) 462-270

Estimating der population by difforentialKELKER G I 1940 a of the Utah Acad of Scienceshunting loss in the sexes Proc

Arts and Letters 17 65-69

_ 1943 Sex ratio equations and formulas for

deturminlrg wildlife populations Proc of the Utach Acad of

Arts and ottier 20 189-191Sciences

KIKKAWA J 1964 Movoment activity and disti ibution of small

rodents OlcthrionoMs glareolus and Apodemus svlaticU_ in

woodland Jour Anita Ecol 33259-297

KUC1MUE V V 1964 Now rethods in numorical conseuvs of harruful rodenAt and shrews Reforat Zh Biol No 121204 I_ol Abstr 46 78632)

a useful pLpoUlatio-iLAUGHILIN R 1965 Capacity for increase statictr Jour E(ol 34 77-91

J P S1RiAIGL and J LIBAYLAVOIE G K G 0 ATWELL F N 3VIbK 37 Movonicv of the riceflold rat 1kttuE _tu2_

fTcuroscontin response Lc floodLg -nd ploing as shown by bone eboling Phil Agric 54 325-330

11965 note on the histrry if wArk-rocaot-rLECWlN E

population estitmaes jour Anim Ecol 34(2 493-454

IESLIEi P H 952 The estimation of popltopaactrobtaiined by from datamneans of the capturo-recapture methodlikelihood equations for estimating the death rate I The maximum

Biometrika38 269272

and D E DAVIB 1939the absolute number An attempt to determineof rats on a given area Jour Anin Ecol8 94-113

U 14 ENABIES and Lfertility and S V VENABLESpopulation 1952 Thestructure of the brown ratnorvegcus) in corn-ricks and some other habitats (Ratta Proc ZoolLand 122 187-238

LINCOOI F4 0 1930 Calculating waterfowl abundanceof banding returns Cir on the basis

U S Dept of Agric No 118 LOTKA A J 1925 Elements of Physical Biology 460 p BaltimoreWilliams and Wilkins Co MACLULICH D A 1951 A new technique of animal census withexamples Jour Mammal 32 318-328 MVKSIMOV A A 1963 Methods for locating and charting sites ofpropagation outbreaks of Arvicola terrestKip for counts of itspopulation and forecasts RefOrat Zh B1 (Moscow) No 121199(Biol Abstr 45 49086) IANY B J 1969 Some proprties of a now method of estimatingthe sie of mobile animal populations Biometrika 56(2) 407-410

--and M J PARR 1968popuJation A new method of estimatingsize survivorship and birth raterecapture data from capture-Trans Soc Br Ent 18 81-89 METZGAR L G and R HILL 1971 The measurement of dispersionsmall mammal populations inJour Mammal 52(1) 12-200 MOM) 0 0 1947 Table of equivalent populations of north Americansmall marmals Amer Midl hat 37 223-249 PAULII( G J and D S ROBSON 1969 Statistical calculationschange-in- stmators of

Wildlf 14et 33(1) of population pamprameters Jour1-27 erJu

PELIKA J 3t al 1964 On the quostion of investigating smallmammal by the quadrat method Acta Thoriol 9 1-24

PENDIETON R C 1956 Uses of marking nimals in ecological stLdies Labeling animals with radioisotopes Ecol 37 686689 1

RUPP R S 1966 Generalized equation for the ratio method of estimating population abundance Jour Wildlf tgt 30(3) 523-526

SANCHEZ F F J P SUMANGIL F N SWIHK G C ATWELL A DELA PAZ M W FALL J L LIBAY D 0 SANCHEZ D C TOLENTINO R R WEST and N B KVERNO 1971 Comparative study of populations of Rattus rattus mindanensis on rainfed and irrigatod ricefields of Luzon Philippines Annual Progress Report of the Rodent Research Center 29-37

SCHINDLER U 1959 Forecasting field vole populations Anz Schadlingsk 32 101-106 (For Abstr 21 668)

SEBER G F 1962 The multi-sample single recapture census Biometrika 49 339-349

_ 1965 A note on the multiple recapture census Biometrika 52(i and 2) 249-259

SHKILEVV V 1963 Indexer for predicting the population size of mrine rodents in the Maritime Region (USSR) Referat Zh Biol No 221201 (Wildlf Rev 118-121)

SMIRNOV V S 1967 The estimation of animal numbers based on the analysis of population structure In K Petrusewicz ed 1967 OoocplusmnI~aw Pruductivity of Terrestrial EGosyste 199-224

SOUTHE-R H N 1965 The traplino index to small mamml populatl0io Jour Zool London 147 217-221

STI]EL L F 1946 Experimental analysis of methods for measuring small mammal populations Jour Wildlf Mgc 10 I10159

- 1948 The trapline as a measure of small mammal populations jour Wildif Mgt 12 153-161

- 1954 A comparison of iertain methudq of measuring ranges of small mammals Jour Mammal 35 1-15-

SWINK F N J P SUANGIL G K LAVOIE A DELA PAZ G C AT WELL J L LIBAY and N B IVER10 1969 Population and movement studies Lf ricefreld rats Annual Progress Report of the Rodent Research Center 33-51

47

TABER R D Uses61956 mama of marking -animals in ecological studieseslgia stiis-Markingofmam l standard methods and new development

Ecol 37-681-685

TANAKA R 1954- Yoar1l change in size and structure a ofOlethionos population Hokkaido Jap Jour Ecol 4(2)51-55

___________ 1960 Evidence against reliability ofthe trap-nightindex as a relative measure of population in small mammals Jap

Jour Ed 1o0 (3) -102-05

TESTER J R and D B SINIFF 1965 Aspects of animal movements and home range data obtained by telemetry Trans N Ams Wildlf and Nat Resources Conf 30 379-392

WOODBURY A M 1956 Uses of marking animals in ecological studies Introduction Ecol 37 665

ZIPPIN C 1956 An e-valuation of the romoval methoed of estimating- animal popuntinna Biomtrics 12 163-139

APPENDIX

ADDITIONAL FORMULAS

Ptersen method (BailoY$ 1952)

) (R ) N- M(C + + 1 )

Where

N population size

14 =nuimber tagged in tho f rst period

C total number caught in ~secnrnd period

in 3cnd porodR nnmbor of tagged caught N =+ 4 i

2as = variance of N

y

Whora

N = populat ion Size - + + - +

+ + + previo aslyin arced - M x - numbr ++ ofan~ials - + + + + + + - + +

y proportion uf iixked anirra1Isin the Catch

Stochastic modol (J611 165

1 1

49

Ni population size at time i

M4 =total numnberof mdrked animals in population at time i

number of m ad ails inith sample

n numbor captured in thG ith soamIiple

s number released from the ith sample after marking

= probability that an animnal alive at the moment ofreloase

of the ith sample will survive till the timo of the (i+ i)th

sample (emigration-and death being synonymous for this

purpose) The period of captivity isassumed very short

compared with the interval between sampling

Effective census area (MacLulich 1951)

(+R)(Q ) - 22R 12

Where

A erfective consea a- ca

P =length of qaadra Q width oqadra

Rt roean diametor of home range or ranigo of movemont during

trapp-Ig peaziod

The thesis attached hereto entitled Estimating Population

Parameters of the Ricefield Rat (Rattus rattus mindanensis Mearns)

prepared and submitted by Edwin A Benigno in partial fulfillment of

the requirements for the degree of Master of Science (Applied Zoology) shy

is hereby accepted

Member Guidance Committee Member Guidance Com ittee

Member GuidanceCommitteeMember Guidance Committee(_

PABLO Ji ALFNSO Adviser and Chairman

Guiance Committee

AcoePWt~ aa pa1tial poundalfiltlmeit of the requfrmet for the

legree of Master of Science (Applied ZO Gi

FAUSTINO T ORIILO Dan 0o1ege of Agriculture University of the Philippi es

on________________

4P

-AsKikkawa (1964) himself concluded

The standardization of a single method permitting the minimum expenditure of time and labor for maximum yieldof information on all aspects of a population is probably impossible Design of experiments and observations must be rado in accordance with the specific purpose of the study

In this connection a limited study may provide more meaningful

reslts than a broad one

LITERATURE CITED

ALLEN D 1949 The purposes of mammai population studies Jour Mammal 30(l) 18-21

ANDERSON P K 1961 Density social structure and nonsocialenvironment in the house mouse populations and the implicationsfor regulations of numbers Trans D Y Acad Sci sor 2(23)47-451

ANDREWARTHA H G 1961 Introduction to the study of animal populations 281 p Chicago University of Chicago Press

and L C BIRCH 1954 The distribution andabundance of animals 782 p Chicago University of ChicagoPress

BAILEY N T J 1951 On estimating the size of mobile populationsfrom recapture data Biometrika 38 293-306

1952 Improvements in the interpretation ofrecapture data Jour knin Ecol 21 120-127

BLAIR W F 1940 Home ranges and population of the meadow volein Southern Michigan Jour lilrllf Mgt 4 i49-161

1951 Population structure social behavior andenvironmental relations in a nataral populatiLn of the beachmoase (Peromyspus polionotus leucocephalus) Ornntrib LabVert Biol University of Michigan 48- 1- 47

B0 B Py Jr 1939 The q adrat method of sudying small mammalpopulatiuns Sci Publ Cleveland Mas hat Hiat 5(4 15-77 BuRWW H 194U Territorial behavior and population of somesmall maramals in Southern hichigan Misc Publ Mus Z0al0

University of Michigan 45 3-58

913 Territoriality and home range conc~pts asapplied to mamnals Jour ammal 24 346-352

CIAPMAN D G 1955 Population estimation based on Thange ofcomposition caused by a selective remova Biomcrika 42 (3 and 4) 279-290

3 ROBSONad D i96 The analysis of atch curyeo B-lomtric3 16(3)i 354-368

42

CORMAK I M 1964 Estimates of survival hom the sighting of marked animals Biometrika 51 229-238

1966 A test for equalcatchability Biometrics 22(2) 330-342

1971 The logic of capture-recapturo ostimatosBiomotrics 27(1) 247

DMLE D D 1942 The cottaintail rabbits in Connecticut StateGeol and Nat Hist Surv Bull 65 1-97

DARROCH Js N 1958 The mltiple recapture census I Estimationof a closed population Biometrika 45 343-359

1959 The multiple recapture census IIEstimatiiwhen there is immigration or death Biomotrilca 48 336-351

1961 The two sample capture-recapture census whentagging and sampling are stratified Biometrika 48 241-260 DAVEUPORT L B Jr 1964 Structure of two PeroLscus polionotas

populations at the AEC Savannah Rivor Plant Jour Aammal 45 95-113

DAVIS DE 1953a Analysis of home ran-) from recaoturo data Jour Mammal 34 352-358

_ urRv 1953b The clhracteristics of rat pcpulations

Quart Rev Biol 28 373-401

1964 Manual for analysis of rodent populations-University Microfilms Ann Abor 82 p

J T EMEI nd A W STOKES 1948 Studius 3n hormo range inhown rat Jur Mammal 29 207-225

EBERRrDT T 0 1969 Population estimates from recapturefrequencies Jour 1ildlt Mgt 33(1) 28-39

EGOROV 0 V 1961 Forecasting thu numbor of squirroiC in YakutiyReferat Zh Biol (Moscow) No 30577 (WildI 1Wcl1Q02)

EMLEN J T A M STOKE aij D E 1949 DAVTIO 4etiods forestirniting populations uf brown rats n rXban ahbituo Ecoogy ) 4

EVANS F C and R HOLERIELD 1943 A population study of thebeechey ground squirrel in central California Jour Mammal 24i 231-260

FISHER R A and E B MDRD 1947 The spread of a gone in naturalconditions in a colony of the moth Panaxia domincla L Heredityils 143-174

FORMOZOV A N and Yu A ISAKOV (ed) 1967 Organization andmethods of censusing birds and harmful rodents (Translatedfrom Russian) U S Dept of Interior and Nat Sc FoundationWashington D 0 269 p

GETZ L L 1961 Homo ranges territoriality and movement of themeadow vole Jour Mammal 2 24-36

GRODZINSKI W ot al 1966 Estimation of rodent numbers by meansof prebaiting and intensive removal Acta Thoriol (Warsaw)11 297-314 (Biol Abstr 48 78977)

GUTIERREZ J S 1967 On the statistical problems of establishingeconomic measures of natural resources The Phil Statist 16(I and 2) 31-52

HANSON 1 R 1963 Calculation of productivity survival andabundance of selected vartebrates from sex and agu ratiosWildlf Monographo 9 60 p

HANSSON L 1967 Index lino catches as a basis of populationstudies on small animals Oikos (Sweden) 18 261276 (Biol Abstr 49 81826)

HAYNE D 949 Two methods for estimating populations fromtrapping recordo Jour Mxmal 30 39-411

HENRY C J W S OVERTON and H M WIGT 1970 Dothrtriningparameters for populations by using strucaral models Jourildlf Mgt 34(4) 690-703

JACKSON 1939 The aaalyjis of an anim-il population JqiAnim Ecl 8 238-246

1940 The analysis of a tsc-tse fly populationAnn Fugonis 10 32 1-3c9

S1944 The ann1ysito of a-tsn-tco poundlj PLpulationII Ann Eig)nies 12 17amp-205

_________ 198 h aayif a te-tse fly population III-Ann Eugenics 14 91-108

1JANION M et al 1968 Estimates of numbers of rodents with variable probability of capture Acta Theriol 1 285-294 (Wildlf Rov 134 24)

JOLLY G M 1963 Estimates of population parameters from multiple deterministic mode1recapture data with both death and dilution -

Biometrika 50(1 and 2) 113-126

1965 Explicit estimates from capture-recapture

data with both death and immigration - stochastic model

Biomtrika 52(1 and 2) 225-248

as a mcasure of probableJORGELSEN 0 D 1968 Home rango of small mammals Jour Mammalinteractions among populations

49(2) 104-112

K E 1961 A new method for measuring home ranges ofJUSTICE small mammals Jour Mammal 42(4) 462-270

Estimating der population by difforentialKELKER G I 1940 a of the Utah Acad of Scienceshunting loss in the sexes Proc

Arts and Letters 17 65-69

_ 1943 Sex ratio equations and formulas for

deturminlrg wildlife populations Proc of the Utach Acad of

Arts and ottier 20 189-191Sciences

KIKKAWA J 1964 Movoment activity and disti ibution of small

rodents OlcthrionoMs glareolus and Apodemus svlaticU_ in

woodland Jour Anita Ecol 33259-297

KUC1MUE V V 1964 Now rethods in numorical conseuvs of harruful rodenAt and shrews Reforat Zh Biol No 121204 I_ol Abstr 46 78632)

a useful pLpoUlatio-iLAUGHILIN R 1965 Capacity for increase statictr Jour E(ol 34 77-91

J P S1RiAIGL and J LIBAYLAVOIE G K G 0 ATWELL F N 3VIbK 37 Movonicv of the riceflold rat 1kttuE _tu2_

fTcuroscontin response Lc floodLg -nd ploing as shown by bone eboling Phil Agric 54 325-330

11965 note on the histrry if wArk-rocaot-rLECWlN E

population estitmaes jour Anim Ecol 34(2 493-454

IESLIEi P H 952 The estimation of popltopaactrobtaiined by from datamneans of the capturo-recapture methodlikelihood equations for estimating the death rate I The maximum

Biometrika38 269272

and D E DAVIB 1939the absolute number An attempt to determineof rats on a given area Jour Anin Ecol8 94-113

U 14 ENABIES and Lfertility and S V VENABLESpopulation 1952 Thestructure of the brown ratnorvegcus) in corn-ricks and some other habitats (Ratta Proc ZoolLand 122 187-238

LINCOOI F4 0 1930 Calculating waterfowl abundanceof banding returns Cir on the basis

U S Dept of Agric No 118 LOTKA A J 1925 Elements of Physical Biology 460 p BaltimoreWilliams and Wilkins Co MACLULICH D A 1951 A new technique of animal census withexamples Jour Mammal 32 318-328 MVKSIMOV A A 1963 Methods for locating and charting sites ofpropagation outbreaks of Arvicola terrestKip for counts of itspopulation and forecasts RefOrat Zh B1 (Moscow) No 121199(Biol Abstr 45 49086) IANY B J 1969 Some proprties of a now method of estimatingthe sie of mobile animal populations Biometrika 56(2) 407-410

--and M J PARR 1968popuJation A new method of estimatingsize survivorship and birth raterecapture data from capture-Trans Soc Br Ent 18 81-89 METZGAR L G and R HILL 1971 The measurement of dispersionsmall mammal populations inJour Mammal 52(1) 12-200 MOM) 0 0 1947 Table of equivalent populations of north Americansmall marmals Amer Midl hat 37 223-249 PAULII( G J and D S ROBSON 1969 Statistical calculationschange-in- stmators of

Wildlf 14et 33(1) of population pamprameters Jour1-27 erJu

PELIKA J 3t al 1964 On the quostion of investigating smallmammal by the quadrat method Acta Thoriol 9 1-24

PENDIETON R C 1956 Uses of marking nimals in ecological stLdies Labeling animals with radioisotopes Ecol 37 686689 1

RUPP R S 1966 Generalized equation for the ratio method of estimating population abundance Jour Wildlf tgt 30(3) 523-526

SANCHEZ F F J P SUMANGIL F N SWIHK G C ATWELL A DELA PAZ M W FALL J L LIBAY D 0 SANCHEZ D C TOLENTINO R R WEST and N B KVERNO 1971 Comparative study of populations of Rattus rattus mindanensis on rainfed and irrigatod ricefields of Luzon Philippines Annual Progress Report of the Rodent Research Center 29-37

SCHINDLER U 1959 Forecasting field vole populations Anz Schadlingsk 32 101-106 (For Abstr 21 668)

SEBER G F 1962 The multi-sample single recapture census Biometrika 49 339-349

_ 1965 A note on the multiple recapture census Biometrika 52(i and 2) 249-259

SHKILEVV V 1963 Indexer for predicting the population size of mrine rodents in the Maritime Region (USSR) Referat Zh Biol No 221201 (Wildlf Rev 118-121)

SMIRNOV V S 1967 The estimation of animal numbers based on the analysis of population structure In K Petrusewicz ed 1967 OoocplusmnI~aw Pruductivity of Terrestrial EGosyste 199-224

SOUTHE-R H N 1965 The traplino index to small mamml populatl0io Jour Zool London 147 217-221

STI]EL L F 1946 Experimental analysis of methods for measuring small mammal populations Jour Wildlf Mgc 10 I10159

- 1948 The trapline as a measure of small mammal populations jour Wildif Mgt 12 153-161

- 1954 A comparison of iertain methudq of measuring ranges of small mammals Jour Mammal 35 1-15-

SWINK F N J P SUANGIL G K LAVOIE A DELA PAZ G C AT WELL J L LIBAY and N B IVER10 1969 Population and movement studies Lf ricefreld rats Annual Progress Report of the Rodent Research Center 33-51

47

TABER R D Uses61956 mama of marking -animals in ecological studieseslgia stiis-Markingofmam l standard methods and new development

Ecol 37-681-685

TANAKA R 1954- Yoar1l change in size and structure a ofOlethionos population Hokkaido Jap Jour Ecol 4(2)51-55

___________ 1960 Evidence against reliability ofthe trap-nightindex as a relative measure of population in small mammals Jap

Jour Ed 1o0 (3) -102-05

TESTER J R and D B SINIFF 1965 Aspects of animal movements and home range data obtained by telemetry Trans N Ams Wildlf and Nat Resources Conf 30 379-392

WOODBURY A M 1956 Uses of marking animals in ecological studies Introduction Ecol 37 665

ZIPPIN C 1956 An e-valuation of the romoval methoed of estimating- animal popuntinna Biomtrics 12 163-139

APPENDIX

ADDITIONAL FORMULAS

Ptersen method (BailoY$ 1952)

) (R ) N- M(C + + 1 )

Where

N population size

14 =nuimber tagged in tho f rst period

C total number caught in ~secnrnd period

in 3cnd porodR nnmbor of tagged caught N =+ 4 i

2as = variance of N

y

Whora

N = populat ion Size - + + - +

+ + + previo aslyin arced - M x - numbr ++ ofan~ials - + + + + + + - + +

y proportion uf iixked anirra1Isin the Catch

Stochastic modol (J611 165

1 1

49

Ni population size at time i

M4 =total numnberof mdrked animals in population at time i

number of m ad ails inith sample

n numbor captured in thG ith soamIiple

s number released from the ith sample after marking

= probability that an animnal alive at the moment ofreloase

of the ith sample will survive till the timo of the (i+ i)th

sample (emigration-and death being synonymous for this

purpose) The period of captivity isassumed very short

compared with the interval between sampling

Effective census area (MacLulich 1951)

(+R)(Q ) - 22R 12

Where

A erfective consea a- ca

P =length of qaadra Q width oqadra

Rt roean diametor of home range or ranigo of movemont during

trapp-Ig peaziod

The thesis attached hereto entitled Estimating Population

Parameters of the Ricefield Rat (Rattus rattus mindanensis Mearns)

prepared and submitted by Edwin A Benigno in partial fulfillment of

the requirements for the degree of Master of Science (Applied Zoology) shy

is hereby accepted

Member Guidance Committee Member Guidance Com ittee

Member GuidanceCommitteeMember Guidance Committee(_

PABLO Ji ALFNSO Adviser and Chairman

Guiance Committee

AcoePWt~ aa pa1tial poundalfiltlmeit of the requfrmet for the

legree of Master of Science (Applied ZO Gi

FAUSTINO T ORIILO Dan 0o1ege of Agriculture University of the Philippi es

on________________

LITERATURE CITED

ALLEN D 1949 The purposes of mammai population studies Jour Mammal 30(l) 18-21

ANDERSON P K 1961 Density social structure and nonsocialenvironment in the house mouse populations and the implicationsfor regulations of numbers Trans D Y Acad Sci sor 2(23)47-451

ANDREWARTHA H G 1961 Introduction to the study of animal populations 281 p Chicago University of Chicago Press

and L C BIRCH 1954 The distribution andabundance of animals 782 p Chicago University of ChicagoPress

BAILEY N T J 1951 On estimating the size of mobile populationsfrom recapture data Biometrika 38 293-306

1952 Improvements in the interpretation ofrecapture data Jour knin Ecol 21 120-127

BLAIR W F 1940 Home ranges and population of the meadow volein Southern Michigan Jour lilrllf Mgt 4 i49-161

1951 Population structure social behavior andenvironmental relations in a nataral populatiLn of the beachmoase (Peromyspus polionotus leucocephalus) Ornntrib LabVert Biol University of Michigan 48- 1- 47

B0 B Py Jr 1939 The q adrat method of sudying small mammalpopulatiuns Sci Publ Cleveland Mas hat Hiat 5(4 15-77 BuRWW H 194U Territorial behavior and population of somesmall maramals in Southern hichigan Misc Publ Mus Z0al0

University of Michigan 45 3-58

913 Territoriality and home range conc~pts asapplied to mamnals Jour ammal 24 346-352

CIAPMAN D G 1955 Population estimation based on Thange ofcomposition caused by a selective remova Biomcrika 42 (3 and 4) 279-290

3 ROBSONad D i96 The analysis of atch curyeo B-lomtric3 16(3)i 354-368

42

CORMAK I M 1964 Estimates of survival hom the sighting of marked animals Biometrika 51 229-238

1966 A test for equalcatchability Biometrics 22(2) 330-342

1971 The logic of capture-recapturo ostimatosBiomotrics 27(1) 247

DMLE D D 1942 The cottaintail rabbits in Connecticut StateGeol and Nat Hist Surv Bull 65 1-97

DARROCH Js N 1958 The mltiple recapture census I Estimationof a closed population Biometrika 45 343-359

1959 The multiple recapture census IIEstimatiiwhen there is immigration or death Biomotrilca 48 336-351

1961 The two sample capture-recapture census whentagging and sampling are stratified Biometrika 48 241-260 DAVEUPORT L B Jr 1964 Structure of two PeroLscus polionotas

populations at the AEC Savannah Rivor Plant Jour Aammal 45 95-113

DAVIS DE 1953a Analysis of home ran-) from recaoturo data Jour Mammal 34 352-358

_ urRv 1953b The clhracteristics of rat pcpulations

Quart Rev Biol 28 373-401

1964 Manual for analysis of rodent populations-University Microfilms Ann Abor 82 p

J T EMEI nd A W STOKES 1948 Studius 3n hormo range inhown rat Jur Mammal 29 207-225

EBERRrDT T 0 1969 Population estimates from recapturefrequencies Jour 1ildlt Mgt 33(1) 28-39

EGOROV 0 V 1961 Forecasting thu numbor of squirroiC in YakutiyReferat Zh Biol (Moscow) No 30577 (WildI 1Wcl1Q02)

EMLEN J T A M STOKE aij D E 1949 DAVTIO 4etiods forestirniting populations uf brown rats n rXban ahbituo Ecoogy ) 4

EVANS F C and R HOLERIELD 1943 A population study of thebeechey ground squirrel in central California Jour Mammal 24i 231-260

FISHER R A and E B MDRD 1947 The spread of a gone in naturalconditions in a colony of the moth Panaxia domincla L Heredityils 143-174

FORMOZOV A N and Yu A ISAKOV (ed) 1967 Organization andmethods of censusing birds and harmful rodents (Translatedfrom Russian) U S Dept of Interior and Nat Sc FoundationWashington D 0 269 p

GETZ L L 1961 Homo ranges territoriality and movement of themeadow vole Jour Mammal 2 24-36

GRODZINSKI W ot al 1966 Estimation of rodent numbers by meansof prebaiting and intensive removal Acta Thoriol (Warsaw)11 297-314 (Biol Abstr 48 78977)

GUTIERREZ J S 1967 On the statistical problems of establishingeconomic measures of natural resources The Phil Statist 16(I and 2) 31-52

HANSON 1 R 1963 Calculation of productivity survival andabundance of selected vartebrates from sex and agu ratiosWildlf Monographo 9 60 p

HANSSON L 1967 Index lino catches as a basis of populationstudies on small animals Oikos (Sweden) 18 261276 (Biol Abstr 49 81826)

HAYNE D 949 Two methods for estimating populations fromtrapping recordo Jour Mxmal 30 39-411

HENRY C J W S OVERTON and H M WIGT 1970 Dothrtriningparameters for populations by using strucaral models Jourildlf Mgt 34(4) 690-703

JACKSON 1939 The aaalyjis of an anim-il population JqiAnim Ecl 8 238-246

1940 The analysis of a tsc-tse fly populationAnn Fugonis 10 32 1-3c9

S1944 The ann1ysito of a-tsn-tco poundlj PLpulationII Ann Eig)nies 12 17amp-205

_________ 198 h aayif a te-tse fly population III-Ann Eugenics 14 91-108

1JANION M et al 1968 Estimates of numbers of rodents with variable probability of capture Acta Theriol 1 285-294 (Wildlf Rov 134 24)

JOLLY G M 1963 Estimates of population parameters from multiple deterministic mode1recapture data with both death and dilution -

Biometrika 50(1 and 2) 113-126

1965 Explicit estimates from capture-recapture

data with both death and immigration - stochastic model

Biomtrika 52(1 and 2) 225-248

as a mcasure of probableJORGELSEN 0 D 1968 Home rango of small mammals Jour Mammalinteractions among populations

49(2) 104-112

K E 1961 A new method for measuring home ranges ofJUSTICE small mammals Jour Mammal 42(4) 462-270

Estimating der population by difforentialKELKER G I 1940 a of the Utah Acad of Scienceshunting loss in the sexes Proc

Arts and Letters 17 65-69

_ 1943 Sex ratio equations and formulas for

deturminlrg wildlife populations Proc of the Utach Acad of

Arts and ottier 20 189-191Sciences

KIKKAWA J 1964 Movoment activity and disti ibution of small

rodents OlcthrionoMs glareolus and Apodemus svlaticU_ in

woodland Jour Anita Ecol 33259-297

KUC1MUE V V 1964 Now rethods in numorical conseuvs of harruful rodenAt and shrews Reforat Zh Biol No 121204 I_ol Abstr 46 78632)

a useful pLpoUlatio-iLAUGHILIN R 1965 Capacity for increase statictr Jour E(ol 34 77-91

J P S1RiAIGL and J LIBAYLAVOIE G K G 0 ATWELL F N 3VIbK 37 Movonicv of the riceflold rat 1kttuE _tu2_

fTcuroscontin response Lc floodLg -nd ploing as shown by bone eboling Phil Agric 54 325-330

11965 note on the histrry if wArk-rocaot-rLECWlN E

population estitmaes jour Anim Ecol 34(2 493-454

IESLIEi P H 952 The estimation of popltopaactrobtaiined by from datamneans of the capturo-recapture methodlikelihood equations for estimating the death rate I The maximum

Biometrika38 269272

and D E DAVIB 1939the absolute number An attempt to determineof rats on a given area Jour Anin Ecol8 94-113

U 14 ENABIES and Lfertility and S V VENABLESpopulation 1952 Thestructure of the brown ratnorvegcus) in corn-ricks and some other habitats (Ratta Proc ZoolLand 122 187-238

LINCOOI F4 0 1930 Calculating waterfowl abundanceof banding returns Cir on the basis

U S Dept of Agric No 118 LOTKA A J 1925 Elements of Physical Biology 460 p BaltimoreWilliams and Wilkins Co MACLULICH D A 1951 A new technique of animal census withexamples Jour Mammal 32 318-328 MVKSIMOV A A 1963 Methods for locating and charting sites ofpropagation outbreaks of Arvicola terrestKip for counts of itspopulation and forecasts RefOrat Zh B1 (Moscow) No 121199(Biol Abstr 45 49086) IANY B J 1969 Some proprties of a now method of estimatingthe sie of mobile animal populations Biometrika 56(2) 407-410

--and M J PARR 1968popuJation A new method of estimatingsize survivorship and birth raterecapture data from capture-Trans Soc Br Ent 18 81-89 METZGAR L G and R HILL 1971 The measurement of dispersionsmall mammal populations inJour Mammal 52(1) 12-200 MOM) 0 0 1947 Table of equivalent populations of north Americansmall marmals Amer Midl hat 37 223-249 PAULII( G J and D S ROBSON 1969 Statistical calculationschange-in- stmators of

Wildlf 14et 33(1) of population pamprameters Jour1-27 erJu

PELIKA J 3t al 1964 On the quostion of investigating smallmammal by the quadrat method Acta Thoriol 9 1-24

PENDIETON R C 1956 Uses of marking nimals in ecological stLdies Labeling animals with radioisotopes Ecol 37 686689 1

RUPP R S 1966 Generalized equation for the ratio method of estimating population abundance Jour Wildlf tgt 30(3) 523-526

SANCHEZ F F J P SUMANGIL F N SWIHK G C ATWELL A DELA PAZ M W FALL J L LIBAY D 0 SANCHEZ D C TOLENTINO R R WEST and N B KVERNO 1971 Comparative study of populations of Rattus rattus mindanensis on rainfed and irrigatod ricefields of Luzon Philippines Annual Progress Report of the Rodent Research Center 29-37

SCHINDLER U 1959 Forecasting field vole populations Anz Schadlingsk 32 101-106 (For Abstr 21 668)

SEBER G F 1962 The multi-sample single recapture census Biometrika 49 339-349

_ 1965 A note on the multiple recapture census Biometrika 52(i and 2) 249-259

SHKILEVV V 1963 Indexer for predicting the population size of mrine rodents in the Maritime Region (USSR) Referat Zh Biol No 221201 (Wildlf Rev 118-121)

SMIRNOV V S 1967 The estimation of animal numbers based on the analysis of population structure In K Petrusewicz ed 1967 OoocplusmnI~aw Pruductivity of Terrestrial EGosyste 199-224

SOUTHE-R H N 1965 The traplino index to small mamml populatl0io Jour Zool London 147 217-221

STI]EL L F 1946 Experimental analysis of methods for measuring small mammal populations Jour Wildlf Mgc 10 I10159

- 1948 The trapline as a measure of small mammal populations jour Wildif Mgt 12 153-161

- 1954 A comparison of iertain methudq of measuring ranges of small mammals Jour Mammal 35 1-15-

SWINK F N J P SUANGIL G K LAVOIE A DELA PAZ G C AT WELL J L LIBAY and N B IVER10 1969 Population and movement studies Lf ricefreld rats Annual Progress Report of the Rodent Research Center 33-51

47

TABER R D Uses61956 mama of marking -animals in ecological studieseslgia stiis-Markingofmam l standard methods and new development

Ecol 37-681-685

TANAKA R 1954- Yoar1l change in size and structure a ofOlethionos population Hokkaido Jap Jour Ecol 4(2)51-55

___________ 1960 Evidence against reliability ofthe trap-nightindex as a relative measure of population in small mammals Jap

Jour Ed 1o0 (3) -102-05

TESTER J R and D B SINIFF 1965 Aspects of animal movements and home range data obtained by telemetry Trans N Ams Wildlf and Nat Resources Conf 30 379-392

WOODBURY A M 1956 Uses of marking animals in ecological studies Introduction Ecol 37 665

ZIPPIN C 1956 An e-valuation of the romoval methoed of estimating- animal popuntinna Biomtrics 12 163-139

APPENDIX

ADDITIONAL FORMULAS

Ptersen method (BailoY$ 1952)

) (R ) N- M(C + + 1 )

Where

N population size

14 =nuimber tagged in tho f rst period

C total number caught in ~secnrnd period

in 3cnd porodR nnmbor of tagged caught N =+ 4 i

2as = variance of N

y

Whora

N = populat ion Size - + + - +

+ + + previo aslyin arced - M x - numbr ++ ofan~ials - + + + + + + - + +

y proportion uf iixked anirra1Isin the Catch

Stochastic modol (J611 165

1 1

49

Ni population size at time i

M4 =total numnberof mdrked animals in population at time i

number of m ad ails inith sample

n numbor captured in thG ith soamIiple

s number released from the ith sample after marking

= probability that an animnal alive at the moment ofreloase

of the ith sample will survive till the timo of the (i+ i)th

sample (emigration-and death being synonymous for this

purpose) The period of captivity isassumed very short

compared with the interval between sampling

Effective census area (MacLulich 1951)

(+R)(Q ) - 22R 12

Where

A erfective consea a- ca

P =length of qaadra Q width oqadra

Rt roean diametor of home range or ranigo of movemont during

trapp-Ig peaziod

The thesis attached hereto entitled Estimating Population

Parameters of the Ricefield Rat (Rattus rattus mindanensis Mearns)

prepared and submitted by Edwin A Benigno in partial fulfillment of

the requirements for the degree of Master of Science (Applied Zoology) shy

is hereby accepted

Member Guidance Committee Member Guidance Com ittee

Member GuidanceCommitteeMember Guidance Committee(_

PABLO Ji ALFNSO Adviser and Chairman

Guiance Committee

AcoePWt~ aa pa1tial poundalfiltlmeit of the requfrmet for the

legree of Master of Science (Applied ZO Gi

FAUSTINO T ORIILO Dan 0o1ege of Agriculture University of the Philippi es

on________________

42

CORMAK I M 1964 Estimates of survival hom the sighting of marked animals Biometrika 51 229-238

1966 A test for equalcatchability Biometrics 22(2) 330-342

1971 The logic of capture-recapturo ostimatosBiomotrics 27(1) 247

DMLE D D 1942 The cottaintail rabbits in Connecticut StateGeol and Nat Hist Surv Bull 65 1-97

DARROCH Js N 1958 The mltiple recapture census I Estimationof a closed population Biometrika 45 343-359

1959 The multiple recapture census IIEstimatiiwhen there is immigration or death Biomotrilca 48 336-351

1961 The two sample capture-recapture census whentagging and sampling are stratified Biometrika 48 241-260 DAVEUPORT L B Jr 1964 Structure of two PeroLscus polionotas

populations at the AEC Savannah Rivor Plant Jour Aammal 45 95-113

DAVIS DE 1953a Analysis of home ran-) from recaoturo data Jour Mammal 34 352-358

_ urRv 1953b The clhracteristics of rat pcpulations

Quart Rev Biol 28 373-401

1964 Manual for analysis of rodent populations-University Microfilms Ann Abor 82 p

J T EMEI nd A W STOKES 1948 Studius 3n hormo range inhown rat Jur Mammal 29 207-225

EBERRrDT T 0 1969 Population estimates from recapturefrequencies Jour 1ildlt Mgt 33(1) 28-39

EGOROV 0 V 1961 Forecasting thu numbor of squirroiC in YakutiyReferat Zh Biol (Moscow) No 30577 (WildI 1Wcl1Q02)

EMLEN J T A M STOKE aij D E 1949 DAVTIO 4etiods forestirniting populations uf brown rats n rXban ahbituo Ecoogy ) 4

EVANS F C and R HOLERIELD 1943 A population study of thebeechey ground squirrel in central California Jour Mammal 24i 231-260

FISHER R A and E B MDRD 1947 The spread of a gone in naturalconditions in a colony of the moth Panaxia domincla L Heredityils 143-174

FORMOZOV A N and Yu A ISAKOV (ed) 1967 Organization andmethods of censusing birds and harmful rodents (Translatedfrom Russian) U S Dept of Interior and Nat Sc FoundationWashington D 0 269 p

GETZ L L 1961 Homo ranges territoriality and movement of themeadow vole Jour Mammal 2 24-36

GRODZINSKI W ot al 1966 Estimation of rodent numbers by meansof prebaiting and intensive removal Acta Thoriol (Warsaw)11 297-314 (Biol Abstr 48 78977)

GUTIERREZ J S 1967 On the statistical problems of establishingeconomic measures of natural resources The Phil Statist 16(I and 2) 31-52

HANSON 1 R 1963 Calculation of productivity survival andabundance of selected vartebrates from sex and agu ratiosWildlf Monographo 9 60 p

HANSSON L 1967 Index lino catches as a basis of populationstudies on small animals Oikos (Sweden) 18 261276 (Biol Abstr 49 81826)

HAYNE D 949 Two methods for estimating populations fromtrapping recordo Jour Mxmal 30 39-411

HENRY C J W S OVERTON and H M WIGT 1970 Dothrtriningparameters for populations by using strucaral models Jourildlf Mgt 34(4) 690-703

JACKSON 1939 The aaalyjis of an anim-il population JqiAnim Ecl 8 238-246

1940 The analysis of a tsc-tse fly populationAnn Fugonis 10 32 1-3c9

S1944 The ann1ysito of a-tsn-tco poundlj PLpulationII Ann Eig)nies 12 17amp-205

_________ 198 h aayif a te-tse fly population III-Ann Eugenics 14 91-108

1JANION M et al 1968 Estimates of numbers of rodents with variable probability of capture Acta Theriol 1 285-294 (Wildlf Rov 134 24)

JOLLY G M 1963 Estimates of population parameters from multiple deterministic mode1recapture data with both death and dilution -

Biometrika 50(1 and 2) 113-126

1965 Explicit estimates from capture-recapture

data with both death and immigration - stochastic model

Biomtrika 52(1 and 2) 225-248

as a mcasure of probableJORGELSEN 0 D 1968 Home rango of small mammals Jour Mammalinteractions among populations

49(2) 104-112

K E 1961 A new method for measuring home ranges ofJUSTICE small mammals Jour Mammal 42(4) 462-270

Estimating der population by difforentialKELKER G I 1940 a of the Utah Acad of Scienceshunting loss in the sexes Proc

Arts and Letters 17 65-69

_ 1943 Sex ratio equations and formulas for

deturminlrg wildlife populations Proc of the Utach Acad of

Arts and ottier 20 189-191Sciences

KIKKAWA J 1964 Movoment activity and disti ibution of small

rodents OlcthrionoMs glareolus and Apodemus svlaticU_ in

woodland Jour Anita Ecol 33259-297

KUC1MUE V V 1964 Now rethods in numorical conseuvs of harruful rodenAt and shrews Reforat Zh Biol No 121204 I_ol Abstr 46 78632)

a useful pLpoUlatio-iLAUGHILIN R 1965 Capacity for increase statictr Jour E(ol 34 77-91

J P S1RiAIGL and J LIBAYLAVOIE G K G 0 ATWELL F N 3VIbK 37 Movonicv of the riceflold rat 1kttuE _tu2_

fTcuroscontin response Lc floodLg -nd ploing as shown by bone eboling Phil Agric 54 325-330

11965 note on the histrry if wArk-rocaot-rLECWlN E

population estitmaes jour Anim Ecol 34(2 493-454

IESLIEi P H 952 The estimation of popltopaactrobtaiined by from datamneans of the capturo-recapture methodlikelihood equations for estimating the death rate I The maximum

Biometrika38 269272

and D E DAVIB 1939the absolute number An attempt to determineof rats on a given area Jour Anin Ecol8 94-113

U 14 ENABIES and Lfertility and S V VENABLESpopulation 1952 Thestructure of the brown ratnorvegcus) in corn-ricks and some other habitats (Ratta Proc ZoolLand 122 187-238

LINCOOI F4 0 1930 Calculating waterfowl abundanceof banding returns Cir on the basis

U S Dept of Agric No 118 LOTKA A J 1925 Elements of Physical Biology 460 p BaltimoreWilliams and Wilkins Co MACLULICH D A 1951 A new technique of animal census withexamples Jour Mammal 32 318-328 MVKSIMOV A A 1963 Methods for locating and charting sites ofpropagation outbreaks of Arvicola terrestKip for counts of itspopulation and forecasts RefOrat Zh B1 (Moscow) No 121199(Biol Abstr 45 49086) IANY B J 1969 Some proprties of a now method of estimatingthe sie of mobile animal populations Biometrika 56(2) 407-410

--and M J PARR 1968popuJation A new method of estimatingsize survivorship and birth raterecapture data from capture-Trans Soc Br Ent 18 81-89 METZGAR L G and R HILL 1971 The measurement of dispersionsmall mammal populations inJour Mammal 52(1) 12-200 MOM) 0 0 1947 Table of equivalent populations of north Americansmall marmals Amer Midl hat 37 223-249 PAULII( G J and D S ROBSON 1969 Statistical calculationschange-in- stmators of

Wildlf 14et 33(1) of population pamprameters Jour1-27 erJu

PELIKA J 3t al 1964 On the quostion of investigating smallmammal by the quadrat method Acta Thoriol 9 1-24

PENDIETON R C 1956 Uses of marking nimals in ecological stLdies Labeling animals with radioisotopes Ecol 37 686689 1

RUPP R S 1966 Generalized equation for the ratio method of estimating population abundance Jour Wildlf tgt 30(3) 523-526

SANCHEZ F F J P SUMANGIL F N SWIHK G C ATWELL A DELA PAZ M W FALL J L LIBAY D 0 SANCHEZ D C TOLENTINO R R WEST and N B KVERNO 1971 Comparative study of populations of Rattus rattus mindanensis on rainfed and irrigatod ricefields of Luzon Philippines Annual Progress Report of the Rodent Research Center 29-37

SCHINDLER U 1959 Forecasting field vole populations Anz Schadlingsk 32 101-106 (For Abstr 21 668)

SEBER G F 1962 The multi-sample single recapture census Biometrika 49 339-349

_ 1965 A note on the multiple recapture census Biometrika 52(i and 2) 249-259

SHKILEVV V 1963 Indexer for predicting the population size of mrine rodents in the Maritime Region (USSR) Referat Zh Biol No 221201 (Wildlf Rev 118-121)

SMIRNOV V S 1967 The estimation of animal numbers based on the analysis of population structure In K Petrusewicz ed 1967 OoocplusmnI~aw Pruductivity of Terrestrial EGosyste 199-224

SOUTHE-R H N 1965 The traplino index to small mamml populatl0io Jour Zool London 147 217-221

STI]EL L F 1946 Experimental analysis of methods for measuring small mammal populations Jour Wildlf Mgc 10 I10159

- 1948 The trapline as a measure of small mammal populations jour Wildif Mgt 12 153-161

- 1954 A comparison of iertain methudq of measuring ranges of small mammals Jour Mammal 35 1-15-

SWINK F N J P SUANGIL G K LAVOIE A DELA PAZ G C AT WELL J L LIBAY and N B IVER10 1969 Population and movement studies Lf ricefreld rats Annual Progress Report of the Rodent Research Center 33-51

47

TABER R D Uses61956 mama of marking -animals in ecological studieseslgia stiis-Markingofmam l standard methods and new development

Ecol 37-681-685

TANAKA R 1954- Yoar1l change in size and structure a ofOlethionos population Hokkaido Jap Jour Ecol 4(2)51-55

___________ 1960 Evidence against reliability ofthe trap-nightindex as a relative measure of population in small mammals Jap

Jour Ed 1o0 (3) -102-05

TESTER J R and D B SINIFF 1965 Aspects of animal movements and home range data obtained by telemetry Trans N Ams Wildlf and Nat Resources Conf 30 379-392

WOODBURY A M 1956 Uses of marking animals in ecological studies Introduction Ecol 37 665

ZIPPIN C 1956 An e-valuation of the romoval methoed of estimating- animal popuntinna Biomtrics 12 163-139

APPENDIX

ADDITIONAL FORMULAS

Ptersen method (BailoY$ 1952)

) (R ) N- M(C + + 1 )

Where

N population size

14 =nuimber tagged in tho f rst period

C total number caught in ~secnrnd period

in 3cnd porodR nnmbor of tagged caught N =+ 4 i

2as = variance of N

y

Whora

N = populat ion Size - + + - +

+ + + previo aslyin arced - M x - numbr ++ ofan~ials - + + + + + + - + +

y proportion uf iixked anirra1Isin the Catch

Stochastic modol (J611 165

1 1

49

Ni population size at time i

M4 =total numnberof mdrked animals in population at time i

number of m ad ails inith sample

n numbor captured in thG ith soamIiple

s number released from the ith sample after marking

= probability that an animnal alive at the moment ofreloase

of the ith sample will survive till the timo of the (i+ i)th

sample (emigration-and death being synonymous for this

purpose) The period of captivity isassumed very short

compared with the interval between sampling

Effective census area (MacLulich 1951)

(+R)(Q ) - 22R 12

Where

A erfective consea a- ca

P =length of qaadra Q width oqadra

Rt roean diametor of home range or ranigo of movemont during

trapp-Ig peaziod

The thesis attached hereto entitled Estimating Population

Parameters of the Ricefield Rat (Rattus rattus mindanensis Mearns)

prepared and submitted by Edwin A Benigno in partial fulfillment of

the requirements for the degree of Master of Science (Applied Zoology) shy

is hereby accepted

Member Guidance Committee Member Guidance Com ittee

Member GuidanceCommitteeMember Guidance Committee(_

PABLO Ji ALFNSO Adviser and Chairman

Guiance Committee

AcoePWt~ aa pa1tial poundalfiltlmeit of the requfrmet for the

legree of Master of Science (Applied ZO Gi

FAUSTINO T ORIILO Dan 0o1ege of Agriculture University of the Philippi es

on________________

EVANS F C and R HOLERIELD 1943 A population study of thebeechey ground squirrel in central California Jour Mammal 24i 231-260

FISHER R A and E B MDRD 1947 The spread of a gone in naturalconditions in a colony of the moth Panaxia domincla L Heredityils 143-174

FORMOZOV A N and Yu A ISAKOV (ed) 1967 Organization andmethods of censusing birds and harmful rodents (Translatedfrom Russian) U S Dept of Interior and Nat Sc FoundationWashington D 0 269 p

GETZ L L 1961 Homo ranges territoriality and movement of themeadow vole Jour Mammal 2 24-36

GRODZINSKI W ot al 1966 Estimation of rodent numbers by meansof prebaiting and intensive removal Acta Thoriol (Warsaw)11 297-314 (Biol Abstr 48 78977)

GUTIERREZ J S 1967 On the statistical problems of establishingeconomic measures of natural resources The Phil Statist 16(I and 2) 31-52

HANSON 1 R 1963 Calculation of productivity survival andabundance of selected vartebrates from sex and agu ratiosWildlf Monographo 9 60 p

HANSSON L 1967 Index lino catches as a basis of populationstudies on small animals Oikos (Sweden) 18 261276 (Biol Abstr 49 81826)

HAYNE D 949 Two methods for estimating populations fromtrapping recordo Jour Mxmal 30 39-411

HENRY C J W S OVERTON and H M WIGT 1970 Dothrtriningparameters for populations by using strucaral models Jourildlf Mgt 34(4) 690-703

JACKSON 1939 The aaalyjis of an anim-il population JqiAnim Ecl 8 238-246

1940 The analysis of a tsc-tse fly populationAnn Fugonis 10 32 1-3c9

S1944 The ann1ysito of a-tsn-tco poundlj PLpulationII Ann Eig)nies 12 17amp-205

_________ 198 h aayif a te-tse fly population III-Ann Eugenics 14 91-108

1JANION M et al 1968 Estimates of numbers of rodents with variable probability of capture Acta Theriol 1 285-294 (Wildlf Rov 134 24)

JOLLY G M 1963 Estimates of population parameters from multiple deterministic mode1recapture data with both death and dilution -

Biometrika 50(1 and 2) 113-126

1965 Explicit estimates from capture-recapture

data with both death and immigration - stochastic model

Biomtrika 52(1 and 2) 225-248

as a mcasure of probableJORGELSEN 0 D 1968 Home rango of small mammals Jour Mammalinteractions among populations

49(2) 104-112

K E 1961 A new method for measuring home ranges ofJUSTICE small mammals Jour Mammal 42(4) 462-270

Estimating der population by difforentialKELKER G I 1940 a of the Utah Acad of Scienceshunting loss in the sexes Proc

Arts and Letters 17 65-69

_ 1943 Sex ratio equations and formulas for

deturminlrg wildlife populations Proc of the Utach Acad of

Arts and ottier 20 189-191Sciences

KIKKAWA J 1964 Movoment activity and disti ibution of small

rodents OlcthrionoMs glareolus and Apodemus svlaticU_ in

woodland Jour Anita Ecol 33259-297

KUC1MUE V V 1964 Now rethods in numorical conseuvs of harruful rodenAt and shrews Reforat Zh Biol No 121204 I_ol Abstr 46 78632)

a useful pLpoUlatio-iLAUGHILIN R 1965 Capacity for increase statictr Jour E(ol 34 77-91

J P S1RiAIGL and J LIBAYLAVOIE G K G 0 ATWELL F N 3VIbK 37 Movonicv of the riceflold rat 1kttuE _tu2_

fTcuroscontin response Lc floodLg -nd ploing as shown by bone eboling Phil Agric 54 325-330

11965 note on the histrry if wArk-rocaot-rLECWlN E

population estitmaes jour Anim Ecol 34(2 493-454

IESLIEi P H 952 The estimation of popltopaactrobtaiined by from datamneans of the capturo-recapture methodlikelihood equations for estimating the death rate I The maximum

Biometrika38 269272

and D E DAVIB 1939the absolute number An attempt to determineof rats on a given area Jour Anin Ecol8 94-113

U 14 ENABIES and Lfertility and S V VENABLESpopulation 1952 Thestructure of the brown ratnorvegcus) in corn-ricks and some other habitats (Ratta Proc ZoolLand 122 187-238

LINCOOI F4 0 1930 Calculating waterfowl abundanceof banding returns Cir on the basis

U S Dept of Agric No 118 LOTKA A J 1925 Elements of Physical Biology 460 p BaltimoreWilliams and Wilkins Co MACLULICH D A 1951 A new technique of animal census withexamples Jour Mammal 32 318-328 MVKSIMOV A A 1963 Methods for locating and charting sites ofpropagation outbreaks of Arvicola terrestKip for counts of itspopulation and forecasts RefOrat Zh B1 (Moscow) No 121199(Biol Abstr 45 49086) IANY B J 1969 Some proprties of a now method of estimatingthe sie of mobile animal populations Biometrika 56(2) 407-410

--and M J PARR 1968popuJation A new method of estimatingsize survivorship and birth raterecapture data from capture-Trans Soc Br Ent 18 81-89 METZGAR L G and R HILL 1971 The measurement of dispersionsmall mammal populations inJour Mammal 52(1) 12-200 MOM) 0 0 1947 Table of equivalent populations of north Americansmall marmals Amer Midl hat 37 223-249 PAULII( G J and D S ROBSON 1969 Statistical calculationschange-in- stmators of

Wildlf 14et 33(1) of population pamprameters Jour1-27 erJu

PELIKA J 3t al 1964 On the quostion of investigating smallmammal by the quadrat method Acta Thoriol 9 1-24

PENDIETON R C 1956 Uses of marking nimals in ecological stLdies Labeling animals with radioisotopes Ecol 37 686689 1

RUPP R S 1966 Generalized equation for the ratio method of estimating population abundance Jour Wildlf tgt 30(3) 523-526

SANCHEZ F F J P SUMANGIL F N SWIHK G C ATWELL A DELA PAZ M W FALL J L LIBAY D 0 SANCHEZ D C TOLENTINO R R WEST and N B KVERNO 1971 Comparative study of populations of Rattus rattus mindanensis on rainfed and irrigatod ricefields of Luzon Philippines Annual Progress Report of the Rodent Research Center 29-37

SCHINDLER U 1959 Forecasting field vole populations Anz Schadlingsk 32 101-106 (For Abstr 21 668)

SEBER G F 1962 The multi-sample single recapture census Biometrika 49 339-349

_ 1965 A note on the multiple recapture census Biometrika 52(i and 2) 249-259

SHKILEVV V 1963 Indexer for predicting the population size of mrine rodents in the Maritime Region (USSR) Referat Zh Biol No 221201 (Wildlf Rev 118-121)

SMIRNOV V S 1967 The estimation of animal numbers based on the analysis of population structure In K Petrusewicz ed 1967 OoocplusmnI~aw Pruductivity of Terrestrial EGosyste 199-224

SOUTHE-R H N 1965 The traplino index to small mamml populatl0io Jour Zool London 147 217-221

STI]EL L F 1946 Experimental analysis of methods for measuring small mammal populations Jour Wildlf Mgc 10 I10159

- 1948 The trapline as a measure of small mammal populations jour Wildif Mgt 12 153-161

- 1954 A comparison of iertain methudq of measuring ranges of small mammals Jour Mammal 35 1-15-

SWINK F N J P SUANGIL G K LAVOIE A DELA PAZ G C AT WELL J L LIBAY and N B IVER10 1969 Population and movement studies Lf ricefreld rats Annual Progress Report of the Rodent Research Center 33-51

47

TABER R D Uses61956 mama of marking -animals in ecological studieseslgia stiis-Markingofmam l standard methods and new development

Ecol 37-681-685

TANAKA R 1954- Yoar1l change in size and structure a ofOlethionos population Hokkaido Jap Jour Ecol 4(2)51-55

___________ 1960 Evidence against reliability ofthe trap-nightindex as a relative measure of population in small mammals Jap

Jour Ed 1o0 (3) -102-05

TESTER J R and D B SINIFF 1965 Aspects of animal movements and home range data obtained by telemetry Trans N Ams Wildlf and Nat Resources Conf 30 379-392

WOODBURY A M 1956 Uses of marking animals in ecological studies Introduction Ecol 37 665

ZIPPIN C 1956 An e-valuation of the romoval methoed of estimating- animal popuntinna Biomtrics 12 163-139

APPENDIX

ADDITIONAL FORMULAS

Ptersen method (BailoY$ 1952)

) (R ) N- M(C + + 1 )

Where

N population size

14 =nuimber tagged in tho f rst period

C total number caught in ~secnrnd period

in 3cnd porodR nnmbor of tagged caught N =+ 4 i

2as = variance of N

y

Whora

N = populat ion Size - + + - +

+ + + previo aslyin arced - M x - numbr ++ ofan~ials - + + + + + + - + +

y proportion uf iixked anirra1Isin the Catch

Stochastic modol (J611 165

1 1

49

Ni population size at time i

M4 =total numnberof mdrked animals in population at time i

number of m ad ails inith sample

n numbor captured in thG ith soamIiple

s number released from the ith sample after marking

= probability that an animnal alive at the moment ofreloase

of the ith sample will survive till the timo of the (i+ i)th

sample (emigration-and death being synonymous for this

purpose) The period of captivity isassumed very short

compared with the interval between sampling

Effective census area (MacLulich 1951)

(+R)(Q ) - 22R 12

Where

A erfective consea a- ca

P =length of qaadra Q width oqadra

Rt roean diametor of home range or ranigo of movemont during

trapp-Ig peaziod

The thesis attached hereto entitled Estimating Population

Parameters of the Ricefield Rat (Rattus rattus mindanensis Mearns)

prepared and submitted by Edwin A Benigno in partial fulfillment of

the requirements for the degree of Master of Science (Applied Zoology) shy

is hereby accepted

Member Guidance Committee Member Guidance Com ittee

Member GuidanceCommitteeMember Guidance Committee(_

PABLO Ji ALFNSO Adviser and Chairman

Guiance Committee

AcoePWt~ aa pa1tial poundalfiltlmeit of the requfrmet for the

legree of Master of Science (Applied ZO Gi

FAUSTINO T ORIILO Dan 0o1ege of Agriculture University of the Philippi es

on________________

_________ 198 h aayif a te-tse fly population III-Ann Eugenics 14 91-108

1JANION M et al 1968 Estimates of numbers of rodents with variable probability of capture Acta Theriol 1 285-294 (Wildlf Rov 134 24)

JOLLY G M 1963 Estimates of population parameters from multiple deterministic mode1recapture data with both death and dilution -

Biometrika 50(1 and 2) 113-126

1965 Explicit estimates from capture-recapture

data with both death and immigration - stochastic model

Biomtrika 52(1 and 2) 225-248

as a mcasure of probableJORGELSEN 0 D 1968 Home rango of small mammals Jour Mammalinteractions among populations

49(2) 104-112

K E 1961 A new method for measuring home ranges ofJUSTICE small mammals Jour Mammal 42(4) 462-270

Estimating der population by difforentialKELKER G I 1940 a of the Utah Acad of Scienceshunting loss in the sexes Proc

Arts and Letters 17 65-69

_ 1943 Sex ratio equations and formulas for

deturminlrg wildlife populations Proc of the Utach Acad of

Arts and ottier 20 189-191Sciences

KIKKAWA J 1964 Movoment activity and disti ibution of small

rodents OlcthrionoMs glareolus and Apodemus svlaticU_ in

woodland Jour Anita Ecol 33259-297

KUC1MUE V V 1964 Now rethods in numorical conseuvs of harruful rodenAt and shrews Reforat Zh Biol No 121204 I_ol Abstr 46 78632)

a useful pLpoUlatio-iLAUGHILIN R 1965 Capacity for increase statictr Jour E(ol 34 77-91

J P S1RiAIGL and J LIBAYLAVOIE G K G 0 ATWELL F N 3VIbK 37 Movonicv of the riceflold rat 1kttuE _tu2_

fTcuroscontin response Lc floodLg -nd ploing as shown by bone eboling Phil Agric 54 325-330

11965 note on the histrry if wArk-rocaot-rLECWlN E

population estitmaes jour Anim Ecol 34(2 493-454

IESLIEi P H 952 The estimation of popltopaactrobtaiined by from datamneans of the capturo-recapture methodlikelihood equations for estimating the death rate I The maximum

Biometrika38 269272

and D E DAVIB 1939the absolute number An attempt to determineof rats on a given area Jour Anin Ecol8 94-113

U 14 ENABIES and Lfertility and S V VENABLESpopulation 1952 Thestructure of the brown ratnorvegcus) in corn-ricks and some other habitats (Ratta Proc ZoolLand 122 187-238

LINCOOI F4 0 1930 Calculating waterfowl abundanceof banding returns Cir on the basis

U S Dept of Agric No 118 LOTKA A J 1925 Elements of Physical Biology 460 p BaltimoreWilliams and Wilkins Co MACLULICH D A 1951 A new technique of animal census withexamples Jour Mammal 32 318-328 MVKSIMOV A A 1963 Methods for locating and charting sites ofpropagation outbreaks of Arvicola terrestKip for counts of itspopulation and forecasts RefOrat Zh B1 (Moscow) No 121199(Biol Abstr 45 49086) IANY B J 1969 Some proprties of a now method of estimatingthe sie of mobile animal populations Biometrika 56(2) 407-410

--and M J PARR 1968popuJation A new method of estimatingsize survivorship and birth raterecapture data from capture-Trans Soc Br Ent 18 81-89 METZGAR L G and R HILL 1971 The measurement of dispersionsmall mammal populations inJour Mammal 52(1) 12-200 MOM) 0 0 1947 Table of equivalent populations of north Americansmall marmals Amer Midl hat 37 223-249 PAULII( G J and D S ROBSON 1969 Statistical calculationschange-in- stmators of

Wildlf 14et 33(1) of population pamprameters Jour1-27 erJu

PELIKA J 3t al 1964 On the quostion of investigating smallmammal by the quadrat method Acta Thoriol 9 1-24

PENDIETON R C 1956 Uses of marking nimals in ecological stLdies Labeling animals with radioisotopes Ecol 37 686689 1

RUPP R S 1966 Generalized equation for the ratio method of estimating population abundance Jour Wildlf tgt 30(3) 523-526

SANCHEZ F F J P SUMANGIL F N SWIHK G C ATWELL A DELA PAZ M W FALL J L LIBAY D 0 SANCHEZ D C TOLENTINO R R WEST and N B KVERNO 1971 Comparative study of populations of Rattus rattus mindanensis on rainfed and irrigatod ricefields of Luzon Philippines Annual Progress Report of the Rodent Research Center 29-37

SCHINDLER U 1959 Forecasting field vole populations Anz Schadlingsk 32 101-106 (For Abstr 21 668)

SEBER G F 1962 The multi-sample single recapture census Biometrika 49 339-349

_ 1965 A note on the multiple recapture census Biometrika 52(i and 2) 249-259

SHKILEVV V 1963 Indexer for predicting the population size of mrine rodents in the Maritime Region (USSR) Referat Zh Biol No 221201 (Wildlf Rev 118-121)

SMIRNOV V S 1967 The estimation of animal numbers based on the analysis of population structure In K Petrusewicz ed 1967 OoocplusmnI~aw Pruductivity of Terrestrial EGosyste 199-224

SOUTHE-R H N 1965 The traplino index to small mamml populatl0io Jour Zool London 147 217-221

STI]EL L F 1946 Experimental analysis of methods for measuring small mammal populations Jour Wildlf Mgc 10 I10159

- 1948 The trapline as a measure of small mammal populations jour Wildif Mgt 12 153-161

- 1954 A comparison of iertain methudq of measuring ranges of small mammals Jour Mammal 35 1-15-

SWINK F N J P SUANGIL G K LAVOIE A DELA PAZ G C AT WELL J L LIBAY and N B IVER10 1969 Population and movement studies Lf ricefreld rats Annual Progress Report of the Rodent Research Center 33-51

47

TABER R D Uses61956 mama of marking -animals in ecological studieseslgia stiis-Markingofmam l standard methods and new development

Ecol 37-681-685

TANAKA R 1954- Yoar1l change in size and structure a ofOlethionos population Hokkaido Jap Jour Ecol 4(2)51-55

___________ 1960 Evidence against reliability ofthe trap-nightindex as a relative measure of population in small mammals Jap

Jour Ed 1o0 (3) -102-05

TESTER J R and D B SINIFF 1965 Aspects of animal movements and home range data obtained by telemetry Trans N Ams Wildlf and Nat Resources Conf 30 379-392

WOODBURY A M 1956 Uses of marking animals in ecological studies Introduction Ecol 37 665

ZIPPIN C 1956 An e-valuation of the romoval methoed of estimating- animal popuntinna Biomtrics 12 163-139

APPENDIX

ADDITIONAL FORMULAS

Ptersen method (BailoY$ 1952)

) (R ) N- M(C + + 1 )

Where

N population size

14 =nuimber tagged in tho f rst period

C total number caught in ~secnrnd period

in 3cnd porodR nnmbor of tagged caught N =+ 4 i

2as = variance of N

y

Whora

N = populat ion Size - + + - +

+ + + previo aslyin arced - M x - numbr ++ ofan~ials - + + + + + + - + +

y proportion uf iixked anirra1Isin the Catch

Stochastic modol (J611 165

1 1

49

Ni population size at time i

M4 =total numnberof mdrked animals in population at time i

number of m ad ails inith sample

n numbor captured in thG ith soamIiple

s number released from the ith sample after marking

= probability that an animnal alive at the moment ofreloase

of the ith sample will survive till the timo of the (i+ i)th

sample (emigration-and death being synonymous for this

purpose) The period of captivity isassumed very short

compared with the interval between sampling

Effective census area (MacLulich 1951)

(+R)(Q ) - 22R 12

Where

A erfective consea a- ca

P =length of qaadra Q width oqadra

Rt roean diametor of home range or ranigo of movemont during

trapp-Ig peaziod

The thesis attached hereto entitled Estimating Population

Parameters of the Ricefield Rat (Rattus rattus mindanensis Mearns)

prepared and submitted by Edwin A Benigno in partial fulfillment of

the requirements for the degree of Master of Science (Applied Zoology) shy

is hereby accepted

Member Guidance Committee Member Guidance Com ittee

Member GuidanceCommitteeMember Guidance Committee(_

PABLO Ji ALFNSO Adviser and Chairman

Guiance Committee

AcoePWt~ aa pa1tial poundalfiltlmeit of the requfrmet for the

legree of Master of Science (Applied ZO Gi

FAUSTINO T ORIILO Dan 0o1ege of Agriculture University of the Philippi es

on________________

IESLIEi P H 952 The estimation of popltopaactrobtaiined by from datamneans of the capturo-recapture methodlikelihood equations for estimating the death rate I The maximum

Biometrika38 269272

and D E DAVIB 1939the absolute number An attempt to determineof rats on a given area Jour Anin Ecol8 94-113

U 14 ENABIES and Lfertility and S V VENABLESpopulation 1952 Thestructure of the brown ratnorvegcus) in corn-ricks and some other habitats (Ratta Proc ZoolLand 122 187-238

LINCOOI F4 0 1930 Calculating waterfowl abundanceof banding returns Cir on the basis

U S Dept of Agric No 118 LOTKA A J 1925 Elements of Physical Biology 460 p BaltimoreWilliams and Wilkins Co MACLULICH D A 1951 A new technique of animal census withexamples Jour Mammal 32 318-328 MVKSIMOV A A 1963 Methods for locating and charting sites ofpropagation outbreaks of Arvicola terrestKip for counts of itspopulation and forecasts RefOrat Zh B1 (Moscow) No 121199(Biol Abstr 45 49086) IANY B J 1969 Some proprties of a now method of estimatingthe sie of mobile animal populations Biometrika 56(2) 407-410

--and M J PARR 1968popuJation A new method of estimatingsize survivorship and birth raterecapture data from capture-Trans Soc Br Ent 18 81-89 METZGAR L G and R HILL 1971 The measurement of dispersionsmall mammal populations inJour Mammal 52(1) 12-200 MOM) 0 0 1947 Table of equivalent populations of north Americansmall marmals Amer Midl hat 37 223-249 PAULII( G J and D S ROBSON 1969 Statistical calculationschange-in- stmators of

Wildlf 14et 33(1) of population pamprameters Jour1-27 erJu

PELIKA J 3t al 1964 On the quostion of investigating smallmammal by the quadrat method Acta Thoriol 9 1-24

PENDIETON R C 1956 Uses of marking nimals in ecological stLdies Labeling animals with radioisotopes Ecol 37 686689 1

RUPP R S 1966 Generalized equation for the ratio method of estimating population abundance Jour Wildlf tgt 30(3) 523-526

SANCHEZ F F J P SUMANGIL F N SWIHK G C ATWELL A DELA PAZ M W FALL J L LIBAY D 0 SANCHEZ D C TOLENTINO R R WEST and N B KVERNO 1971 Comparative study of populations of Rattus rattus mindanensis on rainfed and irrigatod ricefields of Luzon Philippines Annual Progress Report of the Rodent Research Center 29-37

SCHINDLER U 1959 Forecasting field vole populations Anz Schadlingsk 32 101-106 (For Abstr 21 668)

SEBER G F 1962 The multi-sample single recapture census Biometrika 49 339-349

_ 1965 A note on the multiple recapture census Biometrika 52(i and 2) 249-259

SHKILEVV V 1963 Indexer for predicting the population size of mrine rodents in the Maritime Region (USSR) Referat Zh Biol No 221201 (Wildlf Rev 118-121)

SMIRNOV V S 1967 The estimation of animal numbers based on the analysis of population structure In K Petrusewicz ed 1967 OoocplusmnI~aw Pruductivity of Terrestrial EGosyste 199-224

SOUTHE-R H N 1965 The traplino index to small mamml populatl0io Jour Zool London 147 217-221

STI]EL L F 1946 Experimental analysis of methods for measuring small mammal populations Jour Wildlf Mgc 10 I10159

- 1948 The trapline as a measure of small mammal populations jour Wildif Mgt 12 153-161

- 1954 A comparison of iertain methudq of measuring ranges of small mammals Jour Mammal 35 1-15-

SWINK F N J P SUANGIL G K LAVOIE A DELA PAZ G C AT WELL J L LIBAY and N B IVER10 1969 Population and movement studies Lf ricefreld rats Annual Progress Report of the Rodent Research Center 33-51

47

TABER R D Uses61956 mama of marking -animals in ecological studieseslgia stiis-Markingofmam l standard methods and new development

Ecol 37-681-685

TANAKA R 1954- Yoar1l change in size and structure a ofOlethionos population Hokkaido Jap Jour Ecol 4(2)51-55

___________ 1960 Evidence against reliability ofthe trap-nightindex as a relative measure of population in small mammals Jap

Jour Ed 1o0 (3) -102-05

TESTER J R and D B SINIFF 1965 Aspects of animal movements and home range data obtained by telemetry Trans N Ams Wildlf and Nat Resources Conf 30 379-392

WOODBURY A M 1956 Uses of marking animals in ecological studies Introduction Ecol 37 665

ZIPPIN C 1956 An e-valuation of the romoval methoed of estimating- animal popuntinna Biomtrics 12 163-139

APPENDIX

ADDITIONAL FORMULAS

Ptersen method (BailoY$ 1952)

) (R ) N- M(C + + 1 )

Where

N population size

14 =nuimber tagged in tho f rst period

C total number caught in ~secnrnd period

in 3cnd porodR nnmbor of tagged caught N =+ 4 i

2as = variance of N

y

Whora

N = populat ion Size - + + - +

+ + + previo aslyin arced - M x - numbr ++ ofan~ials - + + + + + + - + +

y proportion uf iixked anirra1Isin the Catch

Stochastic modol (J611 165

1 1

49

Ni population size at time i

M4 =total numnberof mdrked animals in population at time i

number of m ad ails inith sample

n numbor captured in thG ith soamIiple

s number released from the ith sample after marking

= probability that an animnal alive at the moment ofreloase

of the ith sample will survive till the timo of the (i+ i)th

sample (emigration-and death being synonymous for this

purpose) The period of captivity isassumed very short

compared with the interval between sampling

Effective census area (MacLulich 1951)

(+R)(Q ) - 22R 12

Where

A erfective consea a- ca

P =length of qaadra Q width oqadra

Rt roean diametor of home range or ranigo of movemont during

trapp-Ig peaziod

The thesis attached hereto entitled Estimating Population

Parameters of the Ricefield Rat (Rattus rattus mindanensis Mearns)

prepared and submitted by Edwin A Benigno in partial fulfillment of

the requirements for the degree of Master of Science (Applied Zoology) shy

is hereby accepted

Member Guidance Committee Member Guidance Com ittee

Member GuidanceCommitteeMember Guidance Committee(_

PABLO Ji ALFNSO Adviser and Chairman

Guiance Committee

AcoePWt~ aa pa1tial poundalfiltlmeit of the requfrmet for the

legree of Master of Science (Applied ZO Gi

FAUSTINO T ORIILO Dan 0o1ege of Agriculture University of the Philippi es

on________________

PENDIETON R C 1956 Uses of marking nimals in ecological stLdies Labeling animals with radioisotopes Ecol 37 686689 1

RUPP R S 1966 Generalized equation for the ratio method of estimating population abundance Jour Wildlf tgt 30(3) 523-526

SANCHEZ F F J P SUMANGIL F N SWIHK G C ATWELL A DELA PAZ M W FALL J L LIBAY D 0 SANCHEZ D C TOLENTINO R R WEST and N B KVERNO 1971 Comparative study of populations of Rattus rattus mindanensis on rainfed and irrigatod ricefields of Luzon Philippines Annual Progress Report of the Rodent Research Center 29-37

SCHINDLER U 1959 Forecasting field vole populations Anz Schadlingsk 32 101-106 (For Abstr 21 668)

SEBER G F 1962 The multi-sample single recapture census Biometrika 49 339-349

_ 1965 A note on the multiple recapture census Biometrika 52(i and 2) 249-259

SHKILEVV V 1963 Indexer for predicting the population size of mrine rodents in the Maritime Region (USSR) Referat Zh Biol No 221201 (Wildlf Rev 118-121)

SMIRNOV V S 1967 The estimation of animal numbers based on the analysis of population structure In K Petrusewicz ed 1967 OoocplusmnI~aw Pruductivity of Terrestrial EGosyste 199-224

SOUTHE-R H N 1965 The traplino index to small mamml populatl0io Jour Zool London 147 217-221

STI]EL L F 1946 Experimental analysis of methods for measuring small mammal populations Jour Wildlf Mgc 10 I10159

- 1948 The trapline as a measure of small mammal populations jour Wildif Mgt 12 153-161

- 1954 A comparison of iertain methudq of measuring ranges of small mammals Jour Mammal 35 1-15-

SWINK F N J P SUANGIL G K LAVOIE A DELA PAZ G C AT WELL J L LIBAY and N B IVER10 1969 Population and movement studies Lf ricefreld rats Annual Progress Report of the Rodent Research Center 33-51

47

TABER R D Uses61956 mama of marking -animals in ecological studieseslgia stiis-Markingofmam l standard methods and new development

Ecol 37-681-685

TANAKA R 1954- Yoar1l change in size and structure a ofOlethionos population Hokkaido Jap Jour Ecol 4(2)51-55

___________ 1960 Evidence against reliability ofthe trap-nightindex as a relative measure of population in small mammals Jap

Jour Ed 1o0 (3) -102-05

TESTER J R and D B SINIFF 1965 Aspects of animal movements and home range data obtained by telemetry Trans N Ams Wildlf and Nat Resources Conf 30 379-392

WOODBURY A M 1956 Uses of marking animals in ecological studies Introduction Ecol 37 665

ZIPPIN C 1956 An e-valuation of the romoval methoed of estimating- animal popuntinna Biomtrics 12 163-139

APPENDIX

ADDITIONAL FORMULAS

Ptersen method (BailoY$ 1952)

) (R ) N- M(C + + 1 )

Where

N population size

14 =nuimber tagged in tho f rst period

C total number caught in ~secnrnd period

in 3cnd porodR nnmbor of tagged caught N =+ 4 i

2as = variance of N

y

Whora

N = populat ion Size - + + - +

+ + + previo aslyin arced - M x - numbr ++ ofan~ials - + + + + + + - + +

y proportion uf iixked anirra1Isin the Catch

Stochastic modol (J611 165

1 1

49

Ni population size at time i

M4 =total numnberof mdrked animals in population at time i

number of m ad ails inith sample

n numbor captured in thG ith soamIiple

s number released from the ith sample after marking

= probability that an animnal alive at the moment ofreloase

of the ith sample will survive till the timo of the (i+ i)th

sample (emigration-and death being synonymous for this

purpose) The period of captivity isassumed very short

compared with the interval between sampling

Effective census area (MacLulich 1951)

(+R)(Q ) - 22R 12

Where

A erfective consea a- ca

P =length of qaadra Q width oqadra

Rt roean diametor of home range or ranigo of movemont during

trapp-Ig peaziod

The thesis attached hereto entitled Estimating Population

Parameters of the Ricefield Rat (Rattus rattus mindanensis Mearns)

prepared and submitted by Edwin A Benigno in partial fulfillment of

the requirements for the degree of Master of Science (Applied Zoology) shy

is hereby accepted

Member Guidance Committee Member Guidance Com ittee

Member GuidanceCommitteeMember Guidance Committee(_

PABLO Ji ALFNSO Adviser and Chairman

Guiance Committee

AcoePWt~ aa pa1tial poundalfiltlmeit of the requfrmet for the

legree of Master of Science (Applied ZO Gi

FAUSTINO T ORIILO Dan 0o1ege of Agriculture University of the Philippi es

on________________

47

TABER R D Uses61956 mama of marking -animals in ecological studieseslgia stiis-Markingofmam l standard methods and new development

Ecol 37-681-685

TANAKA R 1954- Yoar1l change in size and structure a ofOlethionos population Hokkaido Jap Jour Ecol 4(2)51-55

___________ 1960 Evidence against reliability ofthe trap-nightindex as a relative measure of population in small mammals Jap

Jour Ed 1o0 (3) -102-05

TESTER J R and D B SINIFF 1965 Aspects of animal movements and home range data obtained by telemetry Trans N Ams Wildlf and Nat Resources Conf 30 379-392

WOODBURY A M 1956 Uses of marking animals in ecological studies Introduction Ecol 37 665

ZIPPIN C 1956 An e-valuation of the romoval methoed of estimating- animal popuntinna Biomtrics 12 163-139

APPENDIX

ADDITIONAL FORMULAS

Ptersen method (BailoY$ 1952)

) (R ) N- M(C + + 1 )

Where

N population size

14 =nuimber tagged in tho f rst period

C total number caught in ~secnrnd period

in 3cnd porodR nnmbor of tagged caught N =+ 4 i

2as = variance of N

y

Whora

N = populat ion Size - + + - +

+ + + previo aslyin arced - M x - numbr ++ ofan~ials - + + + + + + - + +

y proportion uf iixked anirra1Isin the Catch

Stochastic modol (J611 165

1 1

49

Ni population size at time i

M4 =total numnberof mdrked animals in population at time i

number of m ad ails inith sample

n numbor captured in thG ith soamIiple

s number released from the ith sample after marking

= probability that an animnal alive at the moment ofreloase

of the ith sample will survive till the timo of the (i+ i)th

sample (emigration-and death being synonymous for this

purpose) The period of captivity isassumed very short

compared with the interval between sampling

Effective census area (MacLulich 1951)

(+R)(Q ) - 22R 12

Where

A erfective consea a- ca

P =length of qaadra Q width oqadra

Rt roean diametor of home range or ranigo of movemont during

trapp-Ig peaziod

The thesis attached hereto entitled Estimating Population

Parameters of the Ricefield Rat (Rattus rattus mindanensis Mearns)

prepared and submitted by Edwin A Benigno in partial fulfillment of

the requirements for the degree of Master of Science (Applied Zoology) shy

is hereby accepted

Member Guidance Committee Member Guidance Com ittee

Member GuidanceCommitteeMember Guidance Committee(_

PABLO Ji ALFNSO Adviser and Chairman

Guiance Committee

AcoePWt~ aa pa1tial poundalfiltlmeit of the requfrmet for the

legree of Master of Science (Applied ZO Gi

FAUSTINO T ORIILO Dan 0o1ege of Agriculture University of the Philippi es

on________________

APPENDIX

ADDITIONAL FORMULAS

Ptersen method (BailoY$ 1952)

) (R ) N- M(C + + 1 )

Where

N population size

14 =nuimber tagged in tho f rst period

C total number caught in ~secnrnd period

in 3cnd porodR nnmbor of tagged caught N =+ 4 i

2as = variance of N

y

Whora

N = populat ion Size - + + - +

+ + + previo aslyin arced - M x - numbr ++ ofan~ials - + + + + + + - + +

y proportion uf iixked anirra1Isin the Catch

Stochastic modol (J611 165

1 1

49

Ni population size at time i

M4 =total numnberof mdrked animals in population at time i

number of m ad ails inith sample

n numbor captured in thG ith soamIiple

s number released from the ith sample after marking

= probability that an animnal alive at the moment ofreloase

of the ith sample will survive till the timo of the (i+ i)th

sample (emigration-and death being synonymous for this

purpose) The period of captivity isassumed very short

compared with the interval between sampling

Effective census area (MacLulich 1951)

(+R)(Q ) - 22R 12

Where

A erfective consea a- ca

P =length of qaadra Q width oqadra

Rt roean diametor of home range or ranigo of movemont during

trapp-Ig peaziod

The thesis attached hereto entitled Estimating Population

Parameters of the Ricefield Rat (Rattus rattus mindanensis Mearns)

prepared and submitted by Edwin A Benigno in partial fulfillment of

the requirements for the degree of Master of Science (Applied Zoology) shy

is hereby accepted

Member Guidance Committee Member Guidance Com ittee

Member GuidanceCommitteeMember Guidance Committee(_

PABLO Ji ALFNSO Adviser and Chairman

Guiance Committee

AcoePWt~ aa pa1tial poundalfiltlmeit of the requfrmet for the

legree of Master of Science (Applied ZO Gi

FAUSTINO T ORIILO Dan 0o1ege of Agriculture University of the Philippi es

on________________

49

Ni population size at time i

M4 =total numnberof mdrked animals in population at time i

number of m ad ails inith sample

n numbor captured in thG ith soamIiple

s number released from the ith sample after marking

= probability that an animnal alive at the moment ofreloase

of the ith sample will survive till the timo of the (i+ i)th

sample (emigration-and death being synonymous for this

purpose) The period of captivity isassumed very short

compared with the interval between sampling

Effective census area (MacLulich 1951)

(+R)(Q ) - 22R 12

Where

A erfective consea a- ca

P =length of qaadra Q width oqadra

Rt roean diametor of home range or ranigo of movemont during

trapp-Ig peaziod

The thesis attached hereto entitled Estimating Population

Parameters of the Ricefield Rat (Rattus rattus mindanensis Mearns)

prepared and submitted by Edwin A Benigno in partial fulfillment of

the requirements for the degree of Master of Science (Applied Zoology) shy

is hereby accepted

Member Guidance Committee Member Guidance Com ittee

Member GuidanceCommitteeMember Guidance Committee(_

PABLO Ji ALFNSO Adviser and Chairman

Guiance Committee

AcoePWt~ aa pa1tial poundalfiltlmeit of the requfrmet for the

legree of Master of Science (Applied ZO Gi

FAUSTINO T ORIILO Dan 0o1ege of Agriculture University of the Philippi es

on________________

The thesis attached hereto entitled Estimating Population

Parameters of the Ricefield Rat (Rattus rattus mindanensis Mearns)

prepared and submitted by Edwin A Benigno in partial fulfillment of

the requirements for the degree of Master of Science (Applied Zoology) shy

is hereby accepted

Member Guidance Committee Member Guidance Com ittee

Member GuidanceCommitteeMember Guidance Committee(_

PABLO Ji ALFNSO Adviser and Chairman

Guiance Committee

AcoePWt~ aa pa1tial poundalfiltlmeit of the requfrmet for the

legree of Master of Science (Applied ZO Gi

FAUSTINO T ORIILO Dan 0o1ege of Agriculture University of the Philippi es

on________________