POPULATION DENSITY OF BENGAL MONITOR (Varanus bengalensis) AT DIFFERENT HABITATS OF

DISTRICT SWABI, KHYBER PAKHTUNKHWA, PAKISTAN

Gul Zada*, Muhammad Rais, Iftikhar Hussain, Tariq Mehmood and Maqsood Anwar

Department of Wildlife Management, PMAS Arid Agriculture University Rawalpind

* Presenter; Paper emanated from M.Sc Research Report

INTRODUCTION

Bengal Lizard (Order: Squamata; Family: Varanidae; Genus: VARANUS; Species: BENGALENSIS) is a well-known large-sized lizard species in Pakistan.

73 species of Genus Varanus in Africa, Australia and Asia; Nine in Asia; Four in South Asia (reptile-database.org).

The Genus Varanus is represented by three species in Pakistan (Khan 2006).

Conservation Status: Least Concern ( as per IUCN redlist.org accessed 18/04/2011).

Listed in Schedule III (Protected Animals) of KPK Wildlife Act (1975) and KPK Wildlife Rule (1977) (Shafique, 2005).

Easily identifiable: Juveniles colorful with a series of yellow spots and dark transverse bars on dorsal side. Adults have light brown or grey color with dark spots.

Males have flaps near the vent that is formed by clusters of scales. (Auffenberg, 1994 and Khan, 2006).

Lives in burrows/ crevices; Diurnal

Feeds on invertebrates such as, arthropods; also prey upon small birds and their eggs, rats, frogs, fish and rotten flesh (Smith, 1930; Murthy, 1978; Auffenberg, 1979 and Tikader, 1983).

Widely distributed in Pakistan in various habitats, but more abundant in agricultural areas (Auffenberg et al. 1991 and Khan, 2006).

Hunted for pelt used in various products such as shoes and bags etc; eaten, oil extraction.

OBJECTIVE

To estimate density (number of individuals and burrows) of Bengal Lizard at various habitat types viz. agriculture lands, stream banks and muddy houses near human habitations.

OUTCOMESQuantitative data on population will be gathered that could be

used to assess conservation status of lizards of Pakistan in general and varanids in particular.

Baseline data will help design detailed ecological studies.

Study Area Gangodher Village, Tehsil and District Swabi (34° 7' 12" Latitude North, 72° 28' 20"

Longitude East), Khyber Pakhtunkhwa Province, Pakistan

Three sampling units were selected: 1. Zahir Shah Aratt, 2. PalosiKhwar and 3. Gangodher Kaly An area of 20 square kilometer were surveyed within each sampling units.

Each sampling unit represented three distinct habitats viz. agricultural fields (Wheat, Maize, Tobacco and Vegetables) , stream banks and muddy houses (human habitations).

Population and Burrow Density was calculated by dividing number of individuals/ burrows with the area.

Study Period: Eight months; March to November 2010. Study Parameters: Population density and Burrow Density

MATERIALS AND METHODS

Agriculture Fields Stream Bank

Muddy House (Human Habitations)

Population Density: Fixed-width Line Transect

Number of individuals of Bengal Lizard were recorded along a line of predetermined length and width viz. 400 meters and 25 meters (on either side), respectively (Sutherland, 1996).

Area of Transect= Length X 2 Width

= 400 X 2 (25)= 20000 meter square

= 20 square kilometer

Burrow Count

Number of active and passive burrows were counted along the transects.

To differentiate passive from active burrows, openings of burrows were covered with dry vegetation in the evening and were checked in the subsequent morning.

Presence of foot prints, tail trails and removed vegetation indicated the burrow was active.

SURVEY TECHNIQUE

RESULTS

Agriculture Fields

Stream Banks Muddy House (Human

Habitations)

Total

Number Population Density

Number Population Density

Number Population Density

Number Population Density

March 1 0.05 2 0.1 1 0.05 1.33 0.06April 2 0.1 4 0.2 1 0.05 2.33 0.116May 2 0.1 5 0.25 2 0.1 3 0.15June 2 0.1 4 0.2 3 0.15 3 0.15July 5 0.25 8 0.4 4 0.2 5.66 0.28August 0 0 1 0.05 2 0.1 1 0.05September

4 0.2 3 0.15 4 0.2 3.66 0.18

October 3 0.15 3 0.15 4 0.2 3.33 0.167November

3 0.15 3 0.15 4 0.2 3.33 0.167

Total 2.4 0.122 3.37 0.183 2.78 0.139 2.96 0.149

Table 1: Number and Population Density of Bengal Lizard recorded from different habitats during March, 2010 and November, 2010 from Zahir Shah Aratt , District Swabi

Agriculture Fields

Stream Banks Muddy House (Human

Habitations)

Total

Number Population Density

Number Population Density

Number Population Density

Number Population Density

March 2 0.1 3 0.15 1 0.05 2 0.1April 3 0.15 2 0.1 2 0.1 2.33 0.116May 3 0.15 3 0.15 2 0.1 2.66 0.134June 5 0.25 2 0.1 3 0.15 3.33 0.167July 4 0.2 5 0.25 0 0.0 3 0.15August 3 0.15 3 0.15 0 0.0 2 0.1September

3 0.15 1 0.05 3 0.15 2.33 0.116

October 1 0.05 4 0.2 1 0.05 2 0.1November

1 0.05 3 0.15 1 0.05 1.66 0.083

Total 2.78 0.138 2.89 0.144 1.45 0.072 2.37 0.119

Table 2: Number and Population Density of Bengal Lizard recorded from different habitats during March, 2010 and November, 2010 from PalosiKhwar, Disttrict Swabi

Agriculture Fields

Stream Banks Muddy House (Human

Habitations)

Total

Number Population Density

Number

Population Density

Number

Population Density

Number

Population Density

March 2 0.1 2 0.1 0 0.0 1.33 0.06April 3 0.15 2 0.1 0 0.0 1.66 0.083May 3 0.15 2 0.1 0 0.0 1.66 0.083June 3 0.15 2 0.1 1 0.05 2 0.1July 8 0.4 2 0.1 3 0.15 4.33 0.21August 2 0.1 2 0.1 0 0.0 1.33 0.06September

2 0.1 3 0.15 4 0.2 3 0.15

October 3 0.15 2 0.1 2 0.1 2.33 0.12November

3 0.15 2 0.1 2 0.1 2.33 0.12

Total 3.22 0.16 2.11 0.105 1.33 0.06 2.22 0.11

Table 3: Number and Population Density of Bengal Lizard recorded from different habitats during March,2010 and November, 2010 from Gangodher Kaly, Disttrict Swabi

Agriculture Fields Stream Banks Total

Active Passive Active Passive Active Passive

March 3 (0.15) 3 (0.15) 6 (0.3) 4 (0.2) 4.5 (0.22)

3.5 (0.17)

April 4 (0.2) 3 (0;15) 4 (0.2) 5 (0.25) 4 (0.2)

4 (0.2)

May 4 (0.2) 4 (0.2) 7 (0.35)

5 (0.25) 5.5 (0.27)

4.5 (0.22)

June 8 (0.4) 4 (0.2) 13 (0.65)

5 (0.25) 10.5 (0.52)

4.5 (0.22)

July 8 (0.4) 2 (0.1) 15 (0.75)

6 (0.3) 11.5 (0.57)

4 (0.2)

August 4 (0.2) 6 (0.3) 5 (0.25)

8 (0.4) 4.5 (0.22)

7 (0.35)

September 5 (0.25) 4 (0.2) 6 (0.3) 8 (0.4) 5.5 (0.27)

6 (0.3)

October 6 (0.3) 5 (0.25) 5 (0.25)

7 (0.35) 5.5 (0.27)

6 (0.3)

November 5 (0.25) 6 (0.3) 4 (0.2) 8 (0.4) 4.5 (0.22)

7 (0.35)

Total 5.22 (0.26)

4.11 (0.20)

7.22 (0.36)

6.22 (0.31)

6.22 (0.31)

5.1 (0.26)

Table 4: Burrow Number and Density of Bengal Lizard recorded from different habitats during March, 2010 and November, 2010 from Zahir Shah Aratt, District Swabi

Agriculture Fields Stream Banks Total

Active Passive Active Passive Active Passive

March 4 (0.2) 4 (0.2) 7 (0.35)

6 (0.3) 5.5 (0.22)

5 (0.22)

April 7 (0.35) 5 (0.25)

8 (0.4) 10 (0.5)

7.5 (0.37)

7.5 (0.37)

May 7 (0.35) 4 (0.2) 7 (0.35)

2 (0.2) 7 (0.35)

7 (0.32)

June 8 (0.4) 4 (0.2) 15 (0.75)

5 (0.25) 11.5 (0.52)

4.5 (0.22)

July 9 (0.4) 3 (0.15)

14 (0.7)

5 (0.25) 11.5 (0.52)

4 (0.2)

August 4 (0.2) 6 (0.3) 5 (0.25)

5 (0.45) 4.5 (0.22)

5.5 (0.27)

September

4 (0.2) 4 (0.2) 6 (0.3) 7 (0.35) 5 (0.25) 5.5 (0.27)

October 4 (0.2) 5 (0.25) 4 (0.2) 7 (0.35) 4 (0.2) 6 (0.3)

November

3 (0.15) 5 (0.25) 5 (0.25) 7 (0.35) 4 (0.2) 6 (0.3)

Total 5.5 (0.27)

4.4 (0.22)

7.8 (0.39)

6 (0.3) 6.72 (0.33)

5.6 (0.28)

Table 5: Burrow Number and Density of Bengal Lizard recorded from different habitats during March, 2010 and November, 2010 from PalosiKhwar, District Swabi

Agriculture Fields Stream Banks Total

Active Passive Active Passive Active Passive

March 3 (0.15) 5 (0.25)

3 (0.15)

7 (0.35)

3 (0.15) 6 (0.3)

April 7 (0.35) 7 (0.35)

7 (0.35) 5 (0.25)

7 (0.35) 6 (0.3)

May 8 (0.4) 6 (0.3) 8 (0.4) 4 (0.2) 8 (0.4) 5 (0.22)

June 7 (0.35) 4 (0.2) 6 (0.3) 4 (0.2) 7.5 (0.37)

4 (0.2)

July 7 (0.35) 3 (0.15)

8 (0.4) 4 (0.2) 7.5 (0.37)

3.5 (0.17)

August 2 (0.1) 6 (0.3) 1 (0.15) 11 (0.5.5)

1.5 (0.075)

8.5 (0.42)

September 4 (0.2) 7 (0.35) 5 (0.25)

10 (0.5) 4.5 (0.22)

8.5 (0.42)

October 4 (0.2) 7 (035) 5 (0.25) 10 (0.5) 4.5 (0.22)

8.5 (0.42)

November 4 (0.2) 6 (0.3) 5 (0.25) 11 (0.5.5)

4.5 (0.22)

8.5 (0.42)

Total 5.11 (0.25)

5.6 (0.28)

5.33 (0.26)

7.33 (0.36)

6.22 (0.31)

6.5 (0.32)

Table 6: Burrow Number and Density of Bengal Lizard recorded from different habitats during March, 2010 and November, 2010 from Gangodher Kaly, District Swabi

Muddy Houses Agriculture Fields

Stream Banks

Total

Zahir Shah Aratt

0.38* 0.12* 0.18 0.14

Palosi Khwar 0.07* 0.13* 0.14 0.119Gangodher

Kaly0.06* 0.16* 0.1 0.11

District Swabi0.50±0.43 0.13±0.01 0.14±0.02

0.123±0.008

Table 7: Population Density (Mean ± SE) of Bengal Lizard recorded from different habitats of the selected sampling units of District Swabi from March, 2010 to November, 2010.

Agriculture Fields Stream BanksTotal

Active Passive Active Passive Active PassiveZahir Shah Aratt

5.22 4.11* 7.22 6.22* 6.22 5.16Palosi Khwar 5.55* 4.44 7.8* 6 6.72 5.6

Gangodher Kaly 5.11 5.66 5.33 7.33 5.22 6.49District Swabi

3.62± 0.13 3.63± 0.47 4.80±0.74 4.68± 0.414.23± 0.44

4.25± 0.39

Table 8: Burrow Densities (Mean ± SE) of Bengal Lizard recorded from different habitats of the selected sampling units of District Swabi from March, 2010 to November, 2010.

Pair of values marked with * in a row shows significant difference i.e. P<0.05Population Density= Number of individuals per square kilometer

DISCUSSION•No previous study on population status of the species in Pakistan.

•Large lizards account for over 50% of all lizards considered threatened (IUCN, 1990).

•Bengal lizard (Varanusbengalensis) is quite predominant and occurs throughout the Indian subcontinent (Smith, 1935; Murthy, 1978 and 1985; Tikader, 1983;Auffenberg, 1986)

•Many populations of monitor lizards are threatened due to habitat destruction and fragmentation (Pianka, 1969; Auffenberg, 1988; Branch, 1991).

•Members of genus Varanus, the monitor lizards are considered particularly Vulnerable with all 37 species categorized as threatened or endangered by the US Fish and Wildlife Service.

CONCLUSION•Bengal Monitor (Varanus bengalensis) is a widespread and well known large-sized lizard species in Pakistan.

•Using Fixed-width Line Transect Method density (number of individuals and burrows) of Bengal Monitor at different habitats viz. agriculture fields, bank streams and muddy houses near human habitations in District Swabi, Khyber PakhtunKhwa were recorded from March, 2010 to November, 2010.

•Average population densities (per square kilometer) recorded from agriculture fields, bank streams and muddy houses were 0.13±0.01, 0.14±0.01 and 0.50±0.43 respectively.

•Densities of active burrows (per square kilometer) were 3.62±0.13 and 4.80±0.79 in agriculture fields and bank streams respectively.

•Densities of passive burrows were 3.63±0.47 and 4.68±0.32 in agriculture fields and bank streams respectively.

•Higher density of lizard and burrows along bank streams and muddy houses reflected lizard’s habitat preference.

•Trapping of lizards and persecution by locals were recorded as main threats to the species in the area.

THAN

KS!