the diet and the habitat utilisation os badger.pdf

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Thediet and habitat utilisation of the badger Meles meles) in

an

area to the south ofDurhamcity

by

G

Fletcher

A

dissertation submitted in partial

ful f i lmen t

of the requirements

for

thedegreeof Master of Science in Advanced Ecology

BiologicalSciences

TheUniversityofDurham

(1992)

Th e

copyright of this thesis rests with the author.

No quotation from it should be published without

hispriorwritten consent and information derived

from it should be acknowledged.

2 ^

FEB 1993


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C O N T E N T S

T I T L E P A G E

C O N T E N T S I

A B S T R A C T H

L I S T

O F F I G U R E S m

L I S T O F T A B L E S VI

A C K N O W L E D G E M E N T S VH

1.0 I N T R O D U C T I O N 1

1.1 Biology of the badger 2

1.2 Study aims 10

2.0 S T U D Y A R E A 12

2.1 Location and land use 12

2.2 Geology 12

23 Sett locations 16

2 3 1 H ollinside Sett 16

2 3 3 Reservoir Sett 16

2 3 3 Piggery Bank Sett 21

2 3 4 Badger Bank Sett 21

2 3 5 River Bank Sett 21

3.0 M E T H O D S 26

3.1 B a i tmarking 26

3.2 Dung collection 27

33 Dung analysis 27

3.4 E a r th w o r m abundance 30

3.5 Pitfal l trapping 30

3.6 Weather 31

4.0 R E S U L T S 32

5.0 D I S C U S S I O N 73

6.0 S U M M A R Y 81

7.0 R E F E R E N C E S 82


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A B S T R A C T

The study investigates the diet and habitatutilisationof

f ive

badger clans in an

areaofmixedwoodland, pasture and arable land between mid May and mid July 1992.

Duringthe study period 244 faecalsampleswere collected and analysed to determine

the badgers' diet.Baitmarking was used to determine the extent of each clan's home

range. Badger diet was then compared wi thpreyavailability.

The diet consisted predominantly of earthworms. A variety of other

invertebrates and cereal were also taken. Earthworms were

found

to be consumed in

greater volume on 'worm nights' than on 'non-worm nights' and this was the only

correlationfoundbetweenavailabilityin theterritoryand

presence

in the diet for any of

the prey types taken.

There was a negative relationship between the percentage frequency of

occurrence of cereal and earthworms in the diet. This coupledwi ththe fact that theonly

badger clan wi th no cereal available in its

territory

consumed a

significantly

greater

volume of earthworms than the other clans suggested that there was a relationship

between earthworms and cereal in the diet, wi th

badgers

replacing one staple foodby

eating more of another staplefoodaccording toavailability.

The sizes of Coleoptera, larvae and Hymenoptera in the diet were compared

with the

sizes

oftheseprey items available in the habitat. The results clearly showed

that

badgers

were selecting against the

sizes

that were commonly available to them.

They

took

significantly

more of the larger prey items (>10mm) than i f they were taking

themin proportion to theiravailabilityin the habitat.

I I


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L I S T

O F F I G U R E S

Page

F i g 1 The study

area

13

F i g 2

Houghall Farm - showing

field

sizes 14

F i g

3 Houghall Farm - showing crop types andsitesof earthworm 15

sampling and p i t fa l ltraps

F i g 4 Geology of the study

area

17

F i g

5 Position ofbadgersettsand

outlying

holes 18

F i g

6 Hollinsidesett 19

F ig

7 Reservoirsett 20

F i g

8 Piggery Banksett 23

F i g 9

Badger Bank

sett

24

F ig 10 River Banksett 25

F i g 11 Number ofsubsamples neededto obtain 90 of the prey items 29

per

sample

F i g

12 Position of latrines 33

F i g

13 Positions where coloured markers were found and lines 35

connecting them

wi th

the appropriatesett

F i g

14 Homerangesas estimated by bait marking 36

Figs.

15a-e Percentageofeachhabitat type

wi thin

each

territory

37

Figs.16a b A comparison between habitats in terms of number and volume 39

ofearthworms perm

I I I


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Figs.17a-c

A comparison between habitats in terms of Coleoptera, 40

Hymenoptera and larvaeavailability

F i g 18a

Percentagefrequency of occurrence infaecesof

each

prey 44

category,

ignoring

non-fooditems

F ig

18b

Percentageofscatsin

which

eachprey category waspresent, 45

ignoring

non-food

items

F i g 18c

Percentagevolume of

each

prey category,

ignoring

non-food 46

items

Figs.

19a b

Thepercentageoccurrence andpercentagevolume ofeachprey 48

category taken duringeachmonth of the study

F ig

20 Rainfall

and temperature for the study period 49

Figs.

21a b

Percentagefrequency occurrence andpercentagevolume of 51

each

prey category taken on

worm

nights and non-worm nights

Figs.

22a b

Thepercentageoccurrence andpercentagevolume ofeachprey 53

category taken bybadgersof thef ivedifferentclans in the study

area

Figs.23a-n

The

percentage

occurrence and

percentage

volume of

each

prey 55

category taken by thef iveclans

Figs.

24a-e

Temporal variations in meanpercentageoccurrence ofeachprey 59

category during the study period foreachclan

Figs.25a b

Comparison between clans. The meanpercentageoccurrence 63

and mean

percentage

volume of

each

prey taken over the

whole

study period

Figs.

26a-e

Relativeavailabilityofeachprey category ineachterritory 64

F i g

27

Correlation between earthworm and cereal consumption in 71

terms of

percentage

occurrence in the diet

I V


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F i g 28

Correlation between larvae and Hymenoptera consumption in 71

terms ofpercentagevolume in the diet

Figs.29a

-c Comparison betweenpercentagefrequency of occurrence of 72

each

sizeclassof Coleoptera, larvae and Hymenoptera

in

the diet and habitat


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L I S T O F T A B L E S

T A B L E 1.

The

dates

on

which

plastic markers were recovered f o rm

eachlatrine (numbered as inF ig . 12) and the colour ofthese

markers

Page

34

T A B L E

2. Home

range estimates

34

T A B L E3. The number of dungsamplescollected per clan per month

43

T A B L E

4.

Results of the faecal analysis -

expressed

as

percentage

frequency 43

o f occurrence,percentageofscatsandpercentagevolume

T A B L E5.

Datesof

worm

nights that occurred during the study period 50

T A B L E6.

Prey

availability

in the

territory

as a

function

ofpercentage

occurrence of prey in the diet

67

T A B L E

7. Prey

availability

in the

territory

as a

function

of

percentage

volume

in the diet

67

T A B L E8.

Correlations between percentageoccurrence ofdifferentprey 69

types in the diet

T A B L E9.

Correlations between

percentage

volume ofdifferentprey

types in the diet

70

V I


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A C K N O W L E D G E M E N T S

M y thanks to Dr.N .Dunstone fo rhis help and advice on this thesis and

to Dr.

P. Hulme for his advice on the statistical content. I alsowishto thank

N .Bruguier for his

assistance

wi ththe fieldwork.

V I I


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1.0 I N T R O D U C T I O N

A n animal's home range is the

area

overwhichit movesduringthe course of its

activities.The home range mustsatisfythe animal'sbiologicalrequirements and there is

consequently a relationship between home range, size and body weight of

individuals,

group size, and prey abundance,

mobil i ty

anddistribution.Animals,such as carnivores,

which activelysearch for their mobile orwidely distributedfoodoccupy home

ranges

that are, on average, fourtimes larger than the homerangesof browsers that crop their

food.

Badgers are large, clan l iving animals widely distributed throughout Britain.

They

are omnivorous and therefore feed on both mobile and sedentary prey. Badger

density is afunctionof group size andterritorysize(Kruuk 1978a,b). Results of a study

byKruukand Parish (1982) indicated that badger group sizeincreases

wi th

thequality

o f

food

patches(i.e. amount of

food

per patch),

whilst

territory size is afunctionof

dispersal of

patches

(related to climate and heterogeneity of the habitat).

Previous work by Kruuk and Parish (1981) has shown that badgers take

consistently

highlevels of earthworms Lumbricus spp.) in terms of both frequency and

volume.

Other prey items were taken in

proportion

to

availability.

It has been suggested

that the size of badger territories is related not to thetotalbiomass of the animals'

main

food,earthworms, but to thedistributionof places where thisfoodis available atnight

(Kruuk

1978a;

Kruuk

and Parish 1982).

A predator exploitingworms on the surface

would

need a range encompassing

differenthabitats anddifferentmicroclimatesin order to have worms available asoften

as possible

during

thedifferentseasonsand weather types. Such a defended rangecould

be occupied by one predator but the

minimum

range size in this

case

covering various

habitatswouldhave a contorted

outline,

wi tha higher ratio of border to surface

area.

A

more efficient strategy would be to occupy, wi th several conspecifics, an

area

approaching a hexagonal shape,

wi th

a consequently more defensible border

(Kruuk

1978a).

Although

Kruuk

and Parish (1982)foundno correlation between territory size

and the number of badgers inhabiting the territory (group size) the overall badger

density increased strongly

wi th

earthworm biomass. The mechanism by

which worm

biomass may affect badger numbers is not yetknownand it must be noted the

worm


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biomass andproductivityis vastly inexcessof what the

badger

population is estimated

to

consume

(Kruuk

1978a;

Brown

1983).

The relationships between

badger

population size, dispersion and

food

resources

are l ikely tohold onlywhenbadgersare not persecuted and where theyhave

adequate

placesfor digging theirsetts

(Kruuk

and Parish 1982).

Thisstudy aims to use faecal analysis to determinebadgerdiet and to compare

the

food

eaten

wi th

that available in a habitat comprising mixed arable farmland and

deciduous woodland in County Durham. Badger diet w i l l be investigated in terms of

prey types taken and their relative frequency and volume

wi thin

the diet. The home

range

of

each badger

clan

wi thin

the study area

w i l l

be

assessed

so that the type and

proportions of habitat available to

each

clan can be calculated. Measurements of prey

availability

ineachhabitat type wi l l

allow

a comparison to bemadebetween the prey

types (and their relative abundance) available to

badgers

in

each territory.

By

comparing the

food

eatenbyeachclan

wi th

the

food

available to that clan, thedegree

of

selectivity by badgers in the study area can be

assessed

and compared

wi th

the

findingsofKruukand Parish (1981).

1.1 Biology of the badger

The European badger Meles meles) is a member of the

family

Mustelidae and

is the only speciesofbadger inhabitingBritain. They are the largest British carnivore

and are

powerfully

built animals

wi th

a relatively small head, a

thick,

short neck, a

long, wedge-shaped body and a stumpy tail . The legs of the badger are short but

extremely strong andeach

foot

has f ivetoes.They

havelong,

sharpclaws, especially on

the fi-ont feet and together

these

characteristics make the animal an

efficient

digger,

capable of

moving

heavy material in confined

areas.

It is

d i f f i cu l t

to distinguish males

(boars) f r om females (sows) in the field but boarsdo

have

a much broader head and

thickerneck.

Although

classified as a member of the Carnivora, the

badger

is in fact an

omnivore

and this is illustrated in the dentition. The incisors,

canines

and

front

premolars are typical of a carnivore,

whilst

the last premolar and the molars are

flattened and

modified

for crushing and grindinglike the teeth of a

typical

herbivore

(Neal

1948, 1962, 1966, 1977;

Kruuk

1989; Corbet and Harris 1991).


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Being

remarkably adaptable to a great variety of habitats, badgers are

widespread throughout

Britain

and

Ireland

(Corbet and Harris 1991). However, their

density

is very variable due to requirements for suitablesoilfordigging,adequate

food

supply, sufficientcover for protection and freedom of disturbance

f rom

man and his

activities.

The genus

Meles

appears

to have evolved in temperate forests of

Asia

and

spread intoEurope.Primitiveforms were present in the early Pleistocene. By the early

MiddlePleistocene, badgers in Europe were verysimilarto modern

forms.

The earliest

record forBri tain is a 250,000 years oldfossil f r om Cambridgeshire (Cowan 1955).

Badgers have probably inhabited the North-east of England in

fluctuating

numbers

throughout

historic times. Bones of the badger have beenfoundin a number of ancient

caves

in County Durham.

Since the

First Wor ld

War numbers of badgers in

Britain

steadily increased,

reaching a peak in about 1960.Afterthat, numbers fell mainlydue to human

activities,

including road and

rail

accidents, persecution f r om gamekeepers, farmers and rabbit

trappers, poisoning

fi-omhighly

toxic organochlorine cereal seed dressings (Jefferies

1969

and badgerdiggingandbaiting,shooting and gassing (Paget and Patchett 1978).

Legislation(Badgers Act 1973) helped recovery but recently persecution has caused a

dramatic drop in some regions

particularly

in parts of

Yorkshire,

the

Midlands,

Essex

and S. Wales.

Badger densities vary immensely

f r om

habitat to habitat and also fluctuate on a

seasonal

and yearly basis. In the better habitats there can be up to twenty adults per

km2 Atypicaldensity where badgers are common is around ten adults per km^.

The

burrow system of a badger isknownas a sett, provides shelter

during

the

day and is also used for breeding. A sett consists of a system of tunnels and chambers

and

typically

has three to ten entrances, although very largesettscan have as many as

fo r ty or f i f t y . Chambers are usually

lined wi th

bedding

which

may consist ofgrass,

bracken, straw, leaves or moss and

appears

to prevent heat loss. A badger sett can be

distinguished

f r o m

a fox's earth by the much largerheapsofsoiloutside the entrance

and thepresenceofvegetationin the excavated soi l .


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Theentrancesto thesettare typically 300 to 350mm in diameter. Large rabbit

holescan achievea diameter similar to this but wi thin a short distanceof theentrance

the tunnels narrow to about 150mm. The spoil

heap

or mound of earth outside each

entrancecan be very large, may contain up to40m3of

soil

weighing several

tonnes

and

mayhave beenexcavated bygenerationsofbadgers.

The type of soil is an important factor in the choice of site. Sandy soil is

normallypreferred to clay as it iseasyto dig, is dry and therefore relatively warm and

there is

less

danger of the

roof

collapsing. Chalky strata are also used by

badgers

because these provide excellent drainage and are wel l protected by the hard rock.

However, where the chalk is very hard softerstrata

w i l l

bechosen i f available.

Another important factor in site choice is the

presence

of

some

kind

of cover

nearasett.Cover allowsbadgerstoemergeinconspicuously and explains whybadgers

show a marked preferencefor deciduous woods and

copses.

Hedgerows andscrub are

also frequentlyused as

sites.

Coniferous woodland contains comparatively fewsetts,

probably due to a lack of ground cover and the scarcity of suitable food.

The

vast

majority of setts (88 ) are dug on sloping land. This facilitates

removal of the excavated

soi l ,

which spills down theslopeand as sloping land isalso

usually

wel l

drained the

sett

is more

likely

to be dry and warm. The mound which

forms outside theentrancebuilds up to fo rma platform. This formation

catches

wind

eddies f r om any direction, so danger can be assessed by

scents

without the badger

exposing itself

fu l ly

(Neal 1977).

Near any occupiedsett thereis awel l marked system ofpaths.

These

lead

f r om

activeentrancestoplaces of importance such as outlyingsetts, main feeding grounds,

dung pits and drinking places. Constant trampling of paths may denude them of

vegetation and distinct

paths

can often be

followed

in woodland for several hundred

metres.

Paths

oftenf o l l owman-made boundaries

like

fences, hedgerowsand footpaths.

Badgers

fo rm

social groups called clans comprising an

average

of six

individuals, normally consisting of both boars and sows. The term clan

denotes

a

number of individuals collectively inhabiting and usually defending an

area.

The

individuals

are usually though not always, related and do not

necessarily

travel together

(Kruuk 1989). Each clan occupies a territory which is actively defended particularly

during

the

f i r s t

part of the

year.


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Faeces

are usually deposited in

funnel

shaped dung pits about 150mmdeepand

with

asimilardiameter at the top. The pits are not covered after use and several may be

dugclose together. Such an aggregation of pits is called a latrine.About70 of badger

latrines are located on or

near

theterritorial boundary andsomedung pits are usually

alsofound wi th in20m of the sett. Studies have been carried out to show that

badgers

mark

their territories and that latrine use reflects territoriality (Kruuk 1978b;

Cheeseman

et al. 1981) and the findings ofKruuk (1978a) and Pigozzi (1990) both

show that

badgers

defecate most

frequentlynear

the boundary of the

territory.

Badgers have quite an extensive vocal repertoirewhichthey use as a

means

of

communication. However,

scent

is probably the most important

means

of

communication

both wi th in and between social groups. There are various

sources

of

scentincludingthe subcaudal glands, the anal glands, sweat andsebaceousglands, urine

andinterdigitalglands.

The large subcaudal gland is important in the maintenance of

territory

and in

individual

recognitionwi th ina social group. The anal glands of the badger are paired

sac-like structures that produce a strongsmelling,orange secretion whichis frequently

deposited wi th faecesat latrines. Davieset al.(1988) stated that there was littledoubt

that one primary

function

of anal secretion is to signal

species identity.

Their results

also provide

some

evidence that anal secretion contains information about group

identity and that the secretion would be wel l suited to long-termsignalling. This is

consistent wi th the idea that it is deposited around

territory

boundaries for the purpose

o f territorydefence.

Badgers are largely crepuscular and nocturnal, emerging

f r om

the sett usually

around dusk

f r om

May to August and after dark at other times.

Although

there is no

true hibernation, emergence and

activity

are reduced in winter, especially in the north.

During

periods of

severe

fi-ost

badgers

can survive underground for several days

with

nofood.In secluded placesdaylightappearancesare not unusual andbadgersmay lie in

undergrowthaway

f r om

the sett,

particularly

at times of

drought

andfoodshortage.

The home range is anareaoverwhich an animal normally travels in pursuit of

itsroutine activities and is an area

wi th

a certain productivity that meets the energy

requirements of the individual,or group, that occupies it (Jewell 1966). The range, or

home range of the badger is a defendedarea,a proper

territory

in the accepted

sense

of

the

word.

The

ranges

of

individual

badgers tends

to be smaller than that of the whole

clanor group who

live

more orlesstogether in one main sett.


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Various

methods

have been used

to calculate

badger

home ranges. These

include radio tracking and bait marking (Parish and

Kruuk

1982).

Kruuk

(1978b)used

bait marking and radio tracking to calculate the home

ranges

ofbadgersin Wytham

Woodsnear

Oxford.

Anaveragerangeof 80hectareswas found,

wi th

one being only

just over 20hectaresin size. Workcarried out in Scotland

(Kruuk

1989) foundbadger

ranges hereto be larger than in Wytham Woods,

wi th

rangesof between 100 and 300

hectares. Home range

size

seemed to be related to

food availability,

in the Scottish

studyareasKruukfound that abadgerhad towalkfurther to get to a good feeding site,

compared to an animal l ivingin Wytham.

Wi t h radio tracking a map can be drawn for each animal showing locations

where it has

been

observed. A convex polygon drawn around all

these

observation

points forms the

area

that lies in the

badger's

home

range

over that period.

The technique of bait marking involves leaving

food

marked

wi th

chopped-up

plastic outside a sett. The f o l l owing day this plastic (having passed through the

digestive tract of a badger) can be recovered f r omlatrines. Most latrines are located on

territory borders so by using different coloured plastic foreach setta picture ofeach

homerangecan bebuiltup.

In

every

badger range

the animals may use several feeding

areas.

Different

parts

o fthe

rangew i l l

be good feedingsitesatdifferenttimes and

each

site may

gave

periods

when nofoodis available to thebadgers. Badgerscatch worms on the surface at night.

When

feeding in grassland, their foragingefficiencyis related tograsslength.

Within

their ranges, badgers avoid pasture wi th longgrass which has relatively low worm

densities and becauseit

createsd i f f i cu l ty

in

finding

and catching worms

(Kruuket al.

1979).

Kruuk

and Parish (1982)

suggested

that the

size

of territory is related not to the

total

biomass

of the badgers'mainfood,earthworms, but to the distribution ofplaces

where this

food

is available. This fits in

wi th

the

resource

dispersion hypothesis

(Macdonald 1983) where territorysize is related to dispersion offood patches.From

this territories should be larger where patches are more dispersed. However, several

observations by Kruuk and Parish (1987) were not compatible

wi th

the resource

dispersion hypothesis and their study found thatsome changesin territory

size

were not

related tofoodas aresource.


17/95

Territory boundaries are clearly marked and may be aggressively defended.

Paths

often

radiate

f r om

setts but also occur exactly on the border between ranges.

Border paths and latrines are scent marked and tussocks are also used formarking.

Badgers spend a great deal of time on their boundaries and invest a lot of time and

energy defending their active ranges. They are intenselyterritorial, more so than most

other carnivores and can be very aggressive towards their neighbours(Kruuk1989). fa

badger should loseonlya small part ofitsarea,itmightlose a

vital

patch of

food which

couldmake thewholehome range non-viable.

Althoughterritorysizeappearsto be related to the

distribution

offood,thisdoes

notnecessarily mean that it isonly thefoodresource that is being defended.Fighting

only occurs between badgers of thesamesex, boars only

fight

boars and sows only

f i g h tsows. Thissuggestspossible sexual competition and

Kruuk

(1989) has observed

competition

between females for a male rather thanfightsoverfood.It is also possible

that aterritoryis defended

because

of the importance of knowledge of the

distribution

o f resources wi th in the area rather than the resources themselves. It is probably

necessary

for a badger to

know

an area very wel l in order to exploit itefficiently

(Kruuk

1989).

A

considerable amount of research has been carried out on the diet of the

badger. Earthworms

appear

to be the most important

item

in the diet (e.g.

Kruuk

1978b;

Ashby and El l iot 1983; Henry 1985; Neal 1988), though as badgers are largely

opportunisticforagers earthworms and other foods are taken according toavailability.

Therefore

their diet varies

wi th

geographicallocation,habitat types present

wi thin

their

territory,theseasonandprevailingweatherconditionsat any particulartime.

Dietary

information can be obtained

f r om

direct observation, stomach content

analysis and faecal analysis, the later two methods being themainonesused.

Determination of diet fi-om

analyses

of stomach contents has several

disadvantages (Neal1977).Manycorpsesare obtained f romroad accidents

occurring

as

badgers are

leaving

the sett at dusk to go

foraging,

so their stomachs wi l l be empty. The

primarydisadvantage of stomach analysis is that not enough animals are ever

killed

to

enableusefulcomparisons to be made between particularlocalities.

Dung

analysis has important advantages.

Material

can easily be collected in

large quantities throughout the year. This

means

there is an

opportunity

to compare the

food

actually eaten

wi th

what is available in the habitat and so determine any element


18/95

o f

choice or preference. Also the diet of

badgers f r om

a wide range of habitats and

geographical locations can be compared.

There have been many studies of thefoodof the badger in Europe. Studies in

France have been carried out by Henry (1985) and Mouches (1981).Both of

these

studies showed by the use of faecal analysis that earthworms predominated in the diet.

Mouches showed there was a

seasonal

preference for earthworms but that the badger

also took a wide range of otherfooditems. Henry

found

that the diet consisted largely

o f

earthworms except during summer when they were not available and then toads

{Bufo spp.) were taken as an alternative. Other prey items taken included beetles

(Coleoptera),

f rui t ,

fungi

and Hymenoptera.

Skoog

(1970) in a study of the diet of the Swedish badger

found

that their

feeding habits were affected by the availability of food. This was illustrated by

variations

between

differentseasons,years

and

areas.

Kruukand deKock(1981) used

faecal analysis tolook at the frequency of occurrence of

different

foods in the diet of

the badger in northern

I ta ly.

The most important prey item at all times of year was

foundto be f ru i t(particularlyolives Oleaceae)). Earthworms, arthropods, gastropods

and various vertebrates were also taken.

Lups et al.

(1987) carried out a study of the stomach contents of

badgers

in

centralSwitzerland over a period of tenyears(1973 to 1982). Theyfoundearthworms

to

be the most important prey

item

accounting for 25 by volume of stomach contents

and occurring in 54 of stomachs. Although earthworms were

eaten

frequently they

were often in small volumes, whilst other prey items e.g.

wasps

(Hymenoptera),

cherries and plums Prunus spp.) and maize Zeamays) were taken

infrequently

but in

larger volumes.

In

Britain

most recent studies have

found

that earthworms were the major

food

source of

badgers

(e.g.Kruuk 1978a;Kruukand Parish 1981;Neal 1988). Early studies

may not have recorded earthworms in badger

faeces

as they were thought to be entirely

digestible and to leave no

traces

in the dung (Davies 1936).Although dung analysis

carriedout by Davies ignored the earthworm content other prey itemsfoundincluded

rabbits (Lagomorphs), beetles, wheat

Agropyrum

spp.),

oats Avena

spp.) and acorns

Quercus robur). Observation indicated that as wel las earthworms, bee and wasp

nests

(Hymenoptera),birds

eggs

andpoultrywere also taken.


19/95

In

fact, earthworms are not entirely digested and theirchaetaeand gizzard rings

are easily detectable in badger faeces.The number ofchaetaefoundcan be correlated

w i th the number of earthworms ingested (Kruukand Parish 1981) to give an accurate

estimate of earthworm consumption. However Bradbury (1977) favoured the technique

o f counting the absolute number of gizzard rings in the faeces. Each earthworm

possesses

onlyone gizzard

r ing,

they are macroscopic andeasytoidentifyand

ring

size

can be related to the size of the earthworm.

Major workon the diet of the

British

badger has been carried out byKruukand

Parish (1981, 1983). By

means

of faecal analysis they

found

earthworms to be the

dominant

foodof

badgers

in six

different

areasof Scotland. Otherlessimportant foods

included

rabbits, cereals (taken f r o m fields, farm buildings and places where

supplementary feed was provided for

livestock).

Insects and tubers were often taken

and consumed relative to availability. They suggested that badgers change their

foraging

effortto compensate for fluctuations in earthworm availability, consuming a

range of secondary foods

opportunistically.

The importance of earthworms in the diet variedl i t t le in time and between

areas

and there was no correlation w i th availability. The

presence

of earthworms on the

surface

depends

on the weather so they used the concept of a'wormnight' to helpassess

earthworm

availability.

A

worm

night was defined as being when the temperature did

notf a l l

below

0C

and there had been at least 2mm

rain

during the previous 72 hours.

Workby Harris (1982, 1984) on urban

badgers

in

Bristol

showed a different

situation

sincehereearthworms were not the majorfood itemin the diet. Harris showed

bystomach content and dung analysis that thebadgersate an enormous variety offood

and also large quantities of

non-food

items e.g.

grass,

dead leaves, paper and polythene

foodwrappers. They were not specialising in taking any one mainfood item,although

in

autumn

f r u i t

did predominate. In the urban

area

the

badgers

were

exploiting

a

diversity of

food

types in response to an increased proportion of gardens in their

foraging

range.

Another British study which

does

not show earthworms as being the

predominant prey type was conducted by Skinner and Skinner (1988). Their study,

unlikemost others, was carried out in an

area

wherebadgerswere comparatively rare.

Wheat was

found

to be the majorfood

item

and it was suggested that

badgers

foraged

for

wheat before it was ready for harvest, that they ate

f r o m

grain

stores

and

pheasant

feeders

and that they also gleaned wheat fields after the stubble had been burnt.


20/95

Although earthworms were frequentlyeaten throughout the year they were only taken

in relatively small volumes.

Work by Bradbury (1974), Ashby and E l l io t (1983), Neal (1988) and

Shepherdson et ah

(1990) all show earthworms to predominate in the diet. Neal

examined stomach contents and found that earthworms were taken very frequently and

often

inhugequantities and to the exclusion of almost any other prey item. Other items

were very variable andsuggestedrandomforaging.In the autumn

there

was anincrease

inplant material, particularly cereal (wheat and

oats)

and f ine ly ground acorns.

Bradbury (1974), Ashby and El l iot (1983) and Shepherdson

et al

(1990) all

used

faecal analysis.

Shepherdsonet al

(1990) worked in southern England and found

earthworm intake to be correlated

w i th

worm

biomass

but not the number of worm

nights. There was a significant correlation between the amount of timebadgersspent

foraging

in a particular part of their territory and earthworm biomassin that location.

Theysuggestedthat earthworm consumption was dictated

primarily

by

availability.

Bradbury (1974) investigated the diet ofbadgersin Yorkshire and Humberside.

Earthworms were found to be the predominant

food,

occurring frequently in thefaeces

and in large volume. Other prey items included wasp and bumble bee

nests,

beetles,

centipedes

(Chilopoda), earwigs (Dermaptera),

spiders

(Aranae), frogs

{Rana

spp.),

birds, birds eggs, acorns, blackberries

{Rubus fruticosus),

w i nd f a l l apples

Malus

domesticus), cereals,

f u n g i ,

bluebell bulbs {Endymion non-scriptus) pignuts

Conopodium majus) and coal fragments. Grass, clover Trifolium spp.) and dead

deciduous leaves frequently appeared in samples and were

deemed

to be probably

accidentally ingestedwhileforaging.

Ashby

and

E l l io t

(1983) studied the diet of the badger in County Durham.

Earthworms predominated but were reduced in importance

f r o m

September

to February

when their was an increased intake ofseedsand f ru i t .Insectswere mainlyeaten

f r om

late spring to mid autumn; small birds and mammals werealsoa minor component.

1.2 Study aims

The primary aim of this study was to determine the diet of a number of

badger

clans

inhabiting a

heterogeneous

farmland/woodland habitat and to compare

food

eaten

w i thfood availability

in order toassessthedegreeofselectivity.

10


21/95

Baitmarking trials were used toconfirmthe

different

areasutilisedbythe clans

and to assess thepercentage ofeach habitat type present w i th in each range. Faecal

analysis was carried out toassessthe importance of majorfoodtypes in the diet, overa

twomonth period f r o m mid MaytomidJune1992. There was concurrent monitoring

o f

food availability

utilising p i t f a l l

trapping for invertebrates andearthworm counts.

The changingavailabilityof vegetable matter and the climate were also monitored over

the study period.

11


22/95

2.0

S TUDY

A R E A

2.1 Location and land use

The study was carried out

between

mid May and mid July 1992. The study

area

(174.3

hectares in total) is to the south of Durham city and

covers Great

High Wood,

Hollinside Wood and Houghall Farm (NZ279404) (Fig. 1).

Wi th in

this

area

are four

major land use types; woodland,

arable,

pasture and farm buildings. The strip of

woodland consisting of

Great

High Wood and Hollinside Wood is

deciduous

and

approximately 2km long and a maximum of 300m wide. Houghall Farm

covers

an

area

o f 148.4 hectaresand consists of (3%) farm buildings, (29%)

arable

land (wheat and

barley), (65%)pasture(including

permanent

pastureand silage) and (3%) smallstands

o ftrees

(deciduous

and coniferous) (Figs. 2&3).

A l l

of the fields on the farmwerefertilised

w i th

Nitram (nitrogen:

phosphorous:

potassium in a ratio of 20: 20: 10)

between

February and A p r i l (often two or

three

applications during this period).

Crops

(spring and winterwheat and spring and winter

barley) were

also treated w i t h

applications of herbicide, insecticide, fungicide, plant

growth regulator and feed, while fields ofgrassdid notreceiveany ofthese.

The study area is disturbed by human activities in a number of ways.

Disturbance is

concentrated

around the farm buildings but

parties

of school children are

also shown round the farm at intervals. This is restricted to the day time and

wi l l

thereforehavea relatively low impact on

resident

badgers.The farm workers however

cover allpartsof the farm and often work we l l in to the

hours

ofdarkness,frequently

sighting and presumably causing

disturbance

to badgers. Another source of human

interference on the study area is the recreational use (e.g. walking, jogging, cycling,

exercising

dogs

and

horse

riding) of the woodland

area

and the Houghall Discovery

Trai l

(Fig. 1) which

covers

part of the farm land. In thepast

badger

baiting has

been

a

problem in the

area

but recently

there

has

been

a welcome decline in this activity.

2.2Geology

Since

the ice age the River Wear has cut through an original

d r i f t

of clay

overlying fluvioglacial

sand

and

more

recently the river has formed a

f l o od

plain of

12


23/95

Fig . 1.Thestudy

area

200m

1

G r e a t

High Wood

H o l l i n s i d e

Wood

uuifs

^ J ^ H d u i h a l l F a r m

Houghall

Houghall DiscoveryTrail

13


24/95

Fig .

2.

Houghall Farm-showing f ie ldsizes (hectares)

N

0

L

200m

G r e a t High Wood

H o l l i n s

Wood

oiditt

Ho wjn at l F arm \

Houghall

14


25/95

Fig .

3. Houghall Farm - showing crop

types

and

sites

of earthworm sampling and

pi t fal l

traps.

N

200m

G r e a t

High Wood

H o l l i n s i d a

W o o d

ougnalt

outes

^ ^ ^ ^ ^ ^

Houghall

Fartr

Barley

Pasture

Wheat

Woodland

(J) Location of

p i t f a l l

traps

( E )

Earthworm sampling

site


26/95

al luvium

and

gravel

deposits.

Wi th in

the study area three of

these

d r i f tdeposits are

present;

a l luvium, gravelr iver

terrace deposits and

f luvioglacia l

sand

(Fig.

4).

23

Sett locations

The

variety

of

land

use wi th in the study area provides a range of habitats

suitablefor badgers. There are extensive slopes

provided

by thewoodlandand also on

the banks of the

river

and at the sides of some

f ie lds.

These slopes are an

ideal

site for

sett

d igging; faci l i ta t ing

earth removal and drainage.

Five

badger setts are located

w i th i n

the study area

(Fig.

5). As shown on the map the

five setts

were dug

into

either

the

f luv ioglac ia l

sand or the

a l luvium.

These are softer and easier to excavate than the

gravel

river

terrace deposits (Bowen-Jones 1970 and

Moore

1977).

Previous studies by

Gunner (1986) and Porteous (1989) have

both

concentrated on investigating home

ranges of badgers in

these

setts.

2.3.1 Hollinside sett (F ig .6)

This

sett consists of eleven entrances and is situated on a concave,

eastfacing

slope in

Hollinside Wood.

The mature trees near the sett

include

oak (Quercus robur),

rowan

(Sorbus aucuparia),

beech

(Fagus sylvatica),

silver

birch (Betula pendula)

and

sycamore(Acer pseudoplatanus). Other vegetation in the

v icini ty

consists of

holly

{Ilex

aquifolium) and elderberrybushes (Sambucus nigra), bracken (Pteridium aquilinum),

bramble(Rubu s fruticosus),

ivy

(Hedera helix) and dandelion(Taraxacum spp.). At the

beginning i f

the study

period

(mid May)

the

whole

area was covered by a huge number

o f

bluebells (Endymion non-scriptus)

which

made the badger paths

particularly

easyto

see. The bluebells then

gradually

decreased in number

unt i l

none were

l e f t

by the end of

July.

2.3.2 Reservoir sett (Fig. 7)

This

sett also has eleven entrances and is situated on asteep

eastfacing

slope in

Great

High Wood.

It is

less

conspicuous than the

Hollinside

sett, being

furtherfi^om

a

footpath and

w e l l

hidden by vegetation. The mature trees in the area include oak

(Quercus robur),

beech

(Fagus sylvatica), silver birch (Betula pendula), rowan (Sorbus

aucuparia) and sycamore (Acer pseudoplatanus). The sett entrances are

mostly

concealedby

ho l ly

bushes

(Ilex aquifolium),

bracken

(Pteridium aquilinum)

and nettles

(Urtica dioica). Other nearby vegetation includes bramble (Rubus fruticosus),

clover

16


27/95

Fig .4.

Geology of the studyarea.

N

/K

0 200m

J

Fluvio glacial sand

17


28/95

Fig .5.Position

of

badgersetts

and outlying

holes.

19 Activesett

SD

Inactivesett

9 Active outlying

hole

Q Inactiveoutlying

hole

Reservo i rsett

Great

Wood

Hollinside

Wood

Work

Ho l l i ns idesett A

ouanaii

ouset

rarm

W/ iver

Bank sett

N

t

200m

18


29/95


30/95

Fig .

7.

Reservoir Sett.

Main

badger path

\

C

D

Sett entrance

z^-

\

1 r ^ Maturetree

0 im

I 1

?o

b.

\

0

/V

POb

p

I \

I \

\

\

0.

\

/o

20


31/95

(Trifolium spp.) and a small amount ofgrass {Agrostis spp.). L ike theHollinside sett

there were large numbers of bluebells (Endymion non-scriptus) in the area at the

beginningof the study period andtheselasted for a few weeks, clearly showing badger

paths

around the sett.

2.3.3 Piggery Bank sett

(Fig.

8)

There are atotalof

fourteenentrances

to this extensive sett (two more than were

found

by Porteous in 1989). The sett is situated mostly on a

steep,

convex, north facing

slope that curves round to the

east.Unlike

the previous twosettsthis one is largely

located in agrass field w i th little ground cover and a few mature

trees

at itsbase.Six

entrances

are situated in a stand of young conifers and their low

branches

provide

some

cover.

Apart

f r om

the conifers other

trees

in the

v icini ty

include oak

(Quercus robur)

and beech (Fagus sylvaticd). Some hawthornbushes{Crataegus monogyna) are present

at the top of the slope alongw i th small amounts of dandelion {Taraxacum spp.), thistle

{Cirsium spp.), nettle {Urtica dioica), clover (Trifolium spp.), buttercup {Ranunculus

repens), dock {Rumex spp.), stitchwort{Stellaria spp.), speedwell {Veronica spp.) and

reddead nettle{Lamium amplexicaule).

2.3.4 Badger Bank sett (F ig .9)

This sett has twelve entrances, one ofwhich is very large and is located in a

grass

f i e ld .

The other eleven are all on a f a i r ly steepsouth facing bank in a small strip

o f trees

anddenseundergrowth situated between two fields on the farm (one field of

grass

and one of wheat). The sett is

we l l

concealed by tal l grasses {Agrostis spp.),

elderberry {Sambucus nigra) and hawthorn

bushes

{Crataegus monogyna). The

only

mature

trees

in the area are oak {Quercus robur). Vegetation around the sett also

includes thistle {Cirsium spp.), nettle {Urtica dioica), dock {Rumex spp.), bramble

(Rubus fruticosus),

hogweed

{Heracleum sphondylium),

dandelion

(Taraxacum

spp.),

co w parsley

{Anthriscus sylvestris)

and red campion

{Silene dioica).

Balsam

{Impatiens

spp.) and quite a lot of bluebells{Endymion non-scriptus) were present in May. By July

rosebay willowherb {Epilobium angustifolium), harebell {Cam panula rotundifolia),

ragwort

{Senecio jacobaea) and knapweed {Centaurea spp.) were also present.

2.3.5 River Bank sett

(Fig.

10)

This

is the smallest of the

five

setts

w i th

only four

entrances. It is situated on a

southeastfacing slope on the bank of the River Wear. It iswe l l concealed by a large

21


32/95

amount of vegetation including hawthorn (Crataegus monogyna), grass (Agrostis spp.),

hogweed (Heracleum sphondylium), cow parsley (Anthriscus sylvestris), nettle (Urtica

dioica), thistle (Cirsium spp), stitchwort (Stellaria spp.), ground ivy (Glechoma

hederacea), dock (Rumex spp.), bracken (Pteridium aquilinum), campion (Silene spp.)

and bramble (Rubus fruticosus). InJunerosebayw i l lowherb (Epilobium angustifolium)

appeared along w i th smaller quantities of feverfew(Tanacetum parthenium), ragwort

(Senecio jacobaea) and f ie ld scabious(Knautia arvensis).

22


33/95

F i g .8. PiggeryBankSett.

O

Main

badger path

O Sett entrance

Maturetree

Fieldboundary

0

0

0

0

/

/

/

/

0

/0

a

1m

23


34/95

Fig .

9.

Badger

Bank

Sett.

0

L

1m

o

Main

badger path

3 Sett entrance

1^^^^

Maturetree

Fieldboundary

\

0 -

(

-

o

.0

/

0

--Q

0

24


35/95

F i g .

10.

RiverBankSett.

Mainbadger path

O

Sett entrance

Maturetree

-**Fieldboundary

Wo;.

\

\

\

\

\

y

1m

1

25


36/95

3.0

METHODS

The studyareawas searched for badgersetts,outlyingholes and latrines.These

were carefully marked on a map. The

setts

were named as in previous studies (e.g.

Gunner 1986; Porteous 1989) and the latrines were numbered for convenience. Once

the

setts

andoutlyingholes had been located they were checked

for

occupancy. Signs of

an active, occupied sett include freshly excavated earth at the entrances, badger hair

around the entrance of along the badger paths, claw marks on near-by tree trunks, clean

entrancesfree ofleaflitterand cobwebs.

A

pair of crossed twigs were placed in many sett

entrances

andthesewere then

checked the

fo l lo wi ng

day to see if they had been disturbed.

Although

disturbance

indicates thepresenceof an animal it is not possible to tellwhether this was a badger or

another animal e.g. fox or rabbit.

Additionally

the sticks may have been disturbed by a

visiting rather than resident badger. Neal (1948) observed a badger knocking down

sticks placed infour

separate

entrancesof an unoccupied sett. Flattening the

soil

outside

a sett and checking for paw prints the fo l lowingday is also a useful indicator of badger

presence,but aswi ththe sticks method paw printscouldbe le f tby a

visiting

badger.

For

each active sett that was located a sketch map was drawn to show the

number and position of its entrances, nearby landmarks e.g. hedges, fences, mature

trees,

and thelocalbadger

paths

(Figs. 6-10).

Latrineswere located by searching

near

each sett and

fo l lowing

badger paths.

Many latrines were also discovered along footpaths and manmade boundaries e.g.

fences and hedgerows. Al l human and badger paths were

followed

and all field

boundaries and theareaaround thefarm

buildings

were also

searched.

Vegetationaround andnearto each sett was noted at the beginning of the study

periodand anychangesto this during the time of study were also recorded.

3.1Bait

marking

Badgers defecate in latrines,theseareoftenconspicuous and usually located on

the range boundaries or in the

vicinity

of the sett. If it is

known

which

clan of

badgers

is

using each of the latrinesfoundin the study areathen

these

can be used to give an

26


37/95

estimate of the home

range

for

each

clan. The method of bait marking

(Kruuk

1989)

involves feeding the badgersa conspicuous marker which they cannot digest and is

thereforeevacuatedwi t htheirfaecesand deposited in their latrines.

Small pieces

(5mm by 5mm) were cut f rom

brightly

coloured plasticbagsand

mixed

wi t h peanuts and honey. A different colour plastic was allocated to

each sett;

white

for

Hollinside,

red for Piggery Bank, pink for River Bank, blue for Badger Bank,

green for Reservoir and

yellow

for the active

outlying

hole

near

Piggery Bank. A

spoonful

of the

peanut

and honey mixture and appropriate colour plastic was placed

outside

entrances

to

each sett.

The day

fo l lo wi ng

baiting

scats

were found wi th bits of coloured plastic in

them. Bait marking was carried out for all thesettsand the

outlying

hole simultateously

a total of ten times throughout the study period (at intervals of approximately one

week).

3.2 Dung collection

Each latrine was regularly checked for dung (approximately every other day)

between May 11th and July 13th 1992. Any dung found was placed into a plastic bag

using a

trowel.

Each dungsample(scat) consisted of the entire contents of one pit.Each

scatwas placed in aseparatebag wi th a label recording thedateof

collection

and the

latrine

number. Collected dung was then placed in a freezer as soon as possible to

preserve

itfor

subsequent

analysis.

Results of the bait marking

made

it possible to know how many dung

samples

had

been

collected for

each

clan. By the end of the study period 52

samples

had

been

collected

f rom

the Piggery Bank clan, 48

f rom

River Bank, 51

f rom

Badger Bank, 42

f rom

Hollinside

and 51f romReservoir.

33 Dung analysis

I n

the laboratory the

samples

were defrosted in 2

formalin,

then broken up

and washed through a 1.3mm mesh sieve (procedure f rom

Kruuk

and Parish 1981). The

food

remains retained in the sieve were thoroughly rinsed, then examined under water

27


38/95

in

a large, shallow, white dish. They were identified by comparing with a reference

collection.

Inorder to determine theminimumnumber ofsamplesrequired for analysis the

fo l lo wi ngprocedure was used. For the firsttenscatsanalysed, ten 5gsubsampleswere

taken and the number of different prey items in

each

subsample was counted. The

cumulative

percentageprey items found was calculated foreachscat.Thisinformation

was then used to

plot

a graph showing the number ofsubsamples needed per

scat

to

obtain90 of the prey items Fig.11). It was found that f ive5gsubsamplesfromascat

wouldbetween them contain 90 of the prey itemspresentin that

scat.

28


39/95

F i g .11. Number ofsubsamples

needed

to obtain 90 of the prey items persample

+

2s.e.).

110

100

-

T

d

o

CO

s

= 90 -

o

ft

o

a

80 H

70

m

m

6 8 9 10

number of subsamples

29


40/95

Subsequent analyses involved five 5g subsamples taken

fi-om

each scat. For

each subsample the

total

numbers of each kindof prey were counted, or estimated f rom

the number of remains e.g. gizzard rings of earthworms (one per worm, Bradbury

1977),beetle elytra and skins of

caterpillars

and other larvae. Secondly, an estimate was

made by eye, of the relative volume of each prey type as ingested by the badger. For

each sample the estimated relative volume offoodingested was scored on a seven point

scale:absent,

96 (Kruukand Parish 1981).

Additionally, an estimate was made of the size ofindividualprey items ingested. This

was carried out for any larvae, Hymenoptera and Coleoptera in order to make a

comparison wi t hsizescaught in the field. Prey were placed intoa sizeclassbasedon

theirmaximumdimension: 10mm.

3.4Earthwormabundance

The abundanceof earthworms in the badgers' habitat was assessed using the

formalin

extraction method (Raw 1959; Satchell 1969). The procedure was carried out

at ten differentlocations in each habitat and on three different

dates

during the study

period

(June 9th,June23rd and July 7th).

Samplingwas carried out in three habitats; pasture, woodland and arable land.

21of 0.5 formalinwas poured onto anareaof 0.25m During the fo l lowingtwenty

minutes this

area

was watched and any worms appearing on the surface were counted

and collected and later weighed in the laboratory.

3.5PitfaUtrapping

Pitfall

trapping was carried out to

assess

invertebrate

availability

on

four

different

dates

(May 28th,

June

11th,

June

25th, July 9th).

Plastic cups 6.5cm in diameter at the top and 9cmdeepwere placed in holes dug in the

ground.The top of each cup wasflushwi ththe ground and 2

formalin

was poured in

to

each cup to a depth of approximately 2cm. Five cups were placed in a lineat 5m

intervalsin each of

four

habitats; pasture, woodland, wheat and barley, and le f tfor a

week before being collected.

3


41/95

A t

the end of the week they were then taken back to the laboratory where

captures wereidentified,counted and measured. Eachitemwas placedintoa size class;

10mm (based on themaximumdimension).

3.6 Weather

Weather data for the study period were obtainedfi-omthe geography department

of

Durham

University

and included

measurements

of rainfall and minimum

temperatures necessary

for

wormnight

assessment.

31


42/95

4.0

RESULTS

Five

active badgersettswere

found within

the studyarea Fig.5). Two ofthese

were situated in the woodlandarea(Reservoir andHollinsidesetts) and the other three

were situated

wi th in

Houghall Farm (Piggery Bank, Badger Bank and River Bank

setts). The layout of each sett and the badgerpathsin itsvicini tyare shown in Figs. 6-

10.Clear badger

pathscould

beseennearevery sett, often alongside boundaries such as

fences and also between thedifferententrancesof a sett.

Fig. 12 shows the twenty one badger latrines that were found within the study

area. Some of

these

were located near

setts

and the others were all positioned on, or

veryclose to, a man-made boundary e.g. fence, hedge, path.

Baitmarking trials were carried out to ascertain the home range of each clan.

Bait marking was carried out for all the

setts

and theoutlyinghole simultaneously a

totalof ten times throughout the study period. The results ofthesetrials are shown in

Table 1. Coloured markers were recovered f romevery latrine at

some

point during the

study so each latrinecould be attributed to a particular clan. Latrine numbers 2 and 3

both contained faeces wi th red markers and faeces with yellow markers. The red

markers came f rom the Piggery Bank sett and the yellow markers f rom the active

outlyingholenearto this sett. It was concluded thatbadgersusing theoutlyinghole and

the Piggery Band sett were therefore part of the

same

clan.

A l l

the other latrinesonly

ever contained markers of one colour.

Fig. 13 shows the positions where coloured markers were found. Lines were

drawnto connect each latrinewi ththe appropriate sett, six latrines

could

be attributed

tothe Piggery Bank clan,fourto the Badger Bank clan, three to the River Bank clan,

three to the

Hollinside

clan and fiveto the Reservoir clan. Home range couldthen be

estimated byjoiningthe latrines for each sett together to forma convex polygon (Fig.

14).

From this theareasof the homerangeswere estimated (Table 2). Badger Bank and

PiggeryBank clans were estimated to have the largest and very

similarly

sized home

ranges. The next largest home range belonged to the Reservoir clan. The

Hollinside

clanwas estimated to have by far the smallest home range, beingonlyabout one third

ofthe size of the largest home

ranges.

The percentages of each habitat type (pasture, woodland, barley and wheat

with in

each territory are shown in Figs.

15a-e.

No habitat type is present in all

territories

and no

territory

is made up of one habitat alone. Pasture is the dominant

32


43/95

Fig .

12.

Position of latrines.

N

Latrine

number

Dung pit

r e a t High Wood

H o l h n s i d e

Wood

ouses

| haM Farm

^ 1 j j r m

\ H o u g h a l l

0 200m

I

33


44/95

T A B L E

l.The

dates

on which plasticmarkerswere recovered fromeachlatrine

(numbered as inFig. 12) and the colour ofthesemarkers.

M a y

15th

M a y

18th

May

25th

M a y

31st

June

8th

June

15th

June

22nd

June

29th

July

6th

July

13th

1

R R

2

Y

R

3

Y

R

R

4

B

B

B

5

B

6

B

7

R

R

R

8

P P P

9

W

W

W

W

10

G

11

G

G

12

R

R

13

P

P

14

P

P

15

W W W

16

G

17

G

G

G

18

R

R

19

W

W W

20

B

21

G

G

R

= Red (Piggery Bank)

P

= Pink (River Bank)

G = Green (Reservoir)

B = Blue (Badger Bank)

W = White (Hollinside)

Y =Yellow(Outlyinghole)

T A B L E

2.

Home

range

estimates.

H O M E R A N G E

E S T I M A T E

hectares)

P I G G E R Y

B A N K

46.1

R I V E R

B A N K

29.3

B A D G E R B A N K 46.6

H O L L I N S I D E

15.5

R E S E R V O I R

35.7

34


45/95

Fig .13.

Positions where coloured markers werefoundand lines connecting them

wi t hthe appropriatesett.

N

0

200m

..i: .f~

Wo o d

ouses

Mil ,W

Hougha l l

Position ofsett

~ Red marker (Piggery Bank)

Blue marker (Badger Bank)

Pinkmarker (River Bank)

White

marker(Hollinside)

-

Green marker (Reservoir)

Yellow

marker

(Outlying

hole)


46/95

Fig.

14.Home

ranges

as estimated by bait marking

N

0

Piggery Bank

BadgerBank

River

Bank

Hollinside

Reservoir

r e a t High Wood

H o l l i n s i d e

Wood

Houjfs

i o y i h a l l F i r m

H o u g h a l

Firtr

36


47/95

Figs.15a-ePercentageof

each

habitat typewithin

each

territory

Fig.15aReservoir

Fig.15bHollinside

Fig.15cRiver Bank

Fig.

15dBadger Bank

Barley

Wheat

Woodland

Pasture

Fig.

15ePiggery Bank

37


48/95

habitat type in the Badger Bank, Reservoir and Piggery Bank home

ranges.

The

Hollinsidehome range is theonlyone to contain no cereal (wheat or barley).

A l l of the

fo l lo wi ng

testswere carried out on the actual numbers rather than

the percentages displayed in the graphs. Al lt-tests and analyses of variance were

carriedout on data that had been arcsine transformed to produce a normaldistribution.

A nattempt was made to obtainsomeidea of the differences in theavailability

of each food category between habitats. Relative availability was estimated for each

prey category. The results of the

formalin

method of earthworm sampling are displayed

in

Figs. 16a&b. In each habitat the relative number of earthworms present remained

constant during the study period.Pasturei^T^.,^=2.02, P > 0.05), arable 0.80, P >

0.05) and woodland(F ^ ,= 1.58, P > 0.05). However there was a

significant

difference

between the numbers of earthworms found in each habitat

Fj^g^

= 817.19, P< 0.001).

Thegreatest abundanceof earthworms was

found

in pasture and the least in woodland.

Similarly the relative volume of earthworms present in each habitat did not

changeduring the study period Fig. 16b).Pasture = 1.74, P > 0.05), arable (^-2^-,=

0.42, P > 0.05) and woodland (F ^v = 2.95, P > 0.05). As with the number of

earthworms, there was a significant difference between the volume of earthworms

found

in each habitat F^^j,=

1,040,

P < 0.001). Thegreatestvolume of earthworms was

found

in pasture and the least in woodland.

The numbers of Coleopterafoundusingpit fal ltraps indifferenthabitats during

the whole study period are shown in Fig. 17a. The number of Hymenoptera and larvae

found

using

pi t fa l l

traps are

similarly

shown in Figs. 17b&c respectively. The number

ofColeopterafoundindifferenthabitats although meaningless as absolute figures

does

givean

indication

of thedifferenceinavailability between the habitats (x= 1,171, P

e:

03 k- -

c d

= OJ _

i

f

^ 5

cd

P r e y

c a t e g o r y

e

a

t

l

e

y

e

r

s

c d

m

e

a

t

45


56/95

Fi g .

18c Mean

percentage

volume of

each

prey category when

present

in the diet,

ignoringnon-food items (+ 2 s.e.) (numberabovebars representssamplesize)

230 87 16 4 2 2 16 14 12 37 5 2

2

0

0.05), Hymenoptera

{x\=

2.35, P > 0.05), larvae

x\

= 0.03,

P >0.05) and Cereal

y^^ =

3.71, P >0.05). In all months earthworms were taken most

frequently

and Coleoptera the next most frequently. In terms of

percentage

volume in

the diet there was also no significant difference between

each

month of the study for

each

prey category. Earthworms

P^^^.,=

2.48, P > 0.05), Coleoptera (Fj^,^=2.59, P >

0.05), Hymenoptera (F ,3= 1.96, P > 0.05), larvae 0.80, P > 0.05) and cereal

( 2,39= 0.96, P > 0.05). Earthworms were taken in far greater volume than any of the

other prey categories and cereal was probably taken in the smallest volume during all

months of the study.

It

is of interest to determine whether earthworms were taken at particular times

e.g. particularly after

rain.

A

worm

night was defined by

Kruuk

and Parish (1981) as

being a night when the temperature did not fal lbelow 0C and there was at

least

2mm

o f rain

in the preceding 72hrs. To determine when the

worm

nights occurred during the

study the rainfalland minimum temperature values obtained fromDurham University

Observatory (station number 2165)

f r o m

mid May to mid July were acquired (Fig. 20).

Using

thesecriteria Table 5 gives the

worm

nights during the study.

The

percentage

occurrence and

percentage

volume of

each

prey category were

calculated for

worm

nights and for non-worm nights separately and the results are

shown in Figs. 21a&b. There was no significant difference between the

percentage

occurrence for

worm

and non-worm nights for four of the prey categories; earthworms

(X ^

= 0.33, P > 0.05), Coleoptera (x^ = 0.41, P >0.05), Hymenoptera (x^ = 0.02, P >

0.05) and larvae (x^ = 0.98, P > 0.05). There was, however, significant difference

between

percentage

occurrence of cereal on

worm

and non-worm nights (x^,= 4.47, P 0.05),

47


58/95

F i g .19a The percentage occurrence of each prey cate^ry taken

during

each month

of the study

e o

s o \

AO

H

^

30

H

20 \

10 H

i

My n=74

o

J u n *

n=234

B

July

n=113

r y oategory

Fi g .19b

The mean

percentage

volume of

each

prey category taken

duringeach

month

o fthe study (+ 2 s.e.) (number above

bars represents

sample size)

35134

61 2156 30 4 8 4 4 6 6 10 20 12

H

May

1 = 1 J u n *

a July

P r e y

oaiteaory

48


59/95

o

c

.g

2

t

o

u

_>

'5

B

B

2

1

(U

O .

T 3

3

=2

S

E

u

C

CQ

,=8

Cf5

e

-3

0

C

D

O

CO

o

CM

(O

Q

ainiBjadujsi lunuijujy^ jo U J U J ) ||8iu|)sy

49


60/95

T A B L E5.Dates

of

worm

nights that occurred

during

the study

period (w).

M A Y

J U N E

J U L Y

1st

w

2nd

w

3rd

4th

w w

5th

w

w

6th

w

w

7th

w

8th

9th

w

w

10th

w w

11th

w w

12th

w

w

w

13th

w

14th

w

w

15th w

16th

w

17th

18th

19th

20th

21st

22nd

23rd

24th

25th

26th

27th

28th

29th

30th

31st

50


61/95


62/95

Hymenoptera (t,,= 0.19, P > 0.05), larvae t^ =0.68, P > 0.05) and cereal(t,=0.80, P >

0.05).

Thepercentagevolume of earthworms in the diet was significantlydifferenton

wormand non-worm nights t^^g=7.7, P < 0.001), witha greater volume of earthworms

being

consumed onwormnights.

The bait marking trials showedwhichlatrines

each

of thefive

badger

clans were

using

(Fig. 13) and

because

each collected scat had been labelled with the latrine

number it was possible tolookat the diet of

each

of the clans separately (Figs. 22a&b).

B y

separating the clans it can be

seen

that the Reservoir clan is the

only

one of the

five

in whichcereal doesnot figure in the diet.

A l l

other prey categories are consumed by

allf i ve

of the clans.

Toshow the differences between the clans foreachprey category more clearly

Figs.23a -n were plotted. There was no significant difference between the five clans

for

the percentage occurrence of four of the prey categories taken; earthworms {x =

5.23, P > 0.05), Coleoptera ( x = 2.55, P > 0.05), Hymenoptera x\ =2.50, P > 0.05),

and larvae (x = 5.23, P > 0.05). There was however a significant difference between

the percentage occurrence of cereal (Fig. 23i)

(x

^4= 92.25, P < 0.001). In terms of

percentagevolume there was nosignificantdifference between the clans for Coleoptera

(F,,,3= 1.64, P > 0.05), Hymenoptera

(F, ^

= 0.48, P > 0.05) or larvae

(F ,

= 1.28, P >

0.05) consumption. There was asignificantdifference between the clans for

percentage

volume

of both earthworms (F^ ^ = 44.17, P < 0.001) and cereal F^^,= 31.58, P

a

u

o

i2

u

6 0

1

a

u

3

3

O

u

o

u

c

u

S

do

CO

UlOO

II

II

c c

II II II

c c c

0

( L C l D I l I

I I D Q I

I 8 9 J 3

3 B A J I 1

- B J 3 } l l 0 y 3 l l l i i |

0

D

0

0

8

D.

- JJ81l j03 |03

SUJiOlljlJB]

0

0

0

0

10

0 0

n

0

01

mmm |

53


64/95

c

3

u

>

u

^ \

t4_l

O . N

yi .

Xi

c

W5

a

c

a , CO

s

S E

O C

i ?

I -

o +1

00 ^

CO

1 i

a . 3

si)

II J

L

0

Q

t

f

I

0

t

u

1

SlUlOlipjI]

0

0

0

CO

0 0

0

0 0

10

0

n

0

3 i | 0 A \

54


65/95

F i g .

23a

Percentage occurrence of

earthworms

taken

by thef i v eclans

(numberabove bars represents sample size)

Fig .23b Mean

percentage

volume

o f

earthworms

takenby the

five

clans (+ 2 s.e.)


70

0

20

1T0 103 67 57 84

0

k.

c c c

v

0

d

19

a

n

>

a a

c

k.

0

u

k. H

u

0 0 0

ID >

09

c

Q

a

T3

33

E

m

c

a

0

0

a

D

c

s

0

c

ID

O

T3

(9

m

0

3

c

0

0

>

9

e

Fig .23c Percentage occurrence of Coleoptera

takenby the

five

clans


Fig .

23d

Mean

percentage

volume

of Coleoptera

taken

by the fiveclans (+ 2 s.e.)


110

103 67

57 84 27

24

18

14

24

20H

10

H

c

0

t

a

V

C

fl

CD

0

0)

o

c

>

c

m

0

o

T3

(9

CD

0

B

c

0

0

>

e

e

IT

55


66/95

F i g .

23e

Percentage occurrence ofHymenoptera

takenby thef i v eclans

(number

above bars represents sample size)

Fig .

23f Meanpercentagevolumeof

Hymenoptera

takenby the fiveclans (+ 2 s.e.)


7

8 -

.

5

0

c

4

I 3

0

2 ^

110 103 67 57 84

:

0

c

C

c

s d

9

a

03 D

C

k

0 0 0

9

>

a

Q

E

0

a

E

0

>

u

0

e

0

H

4

H

H

F i g .

23g

Percentage occurrence of larvae

takenby thef i v eclans


0

/

0

8

\

5

0

0 ^

3

2 -

110 103 67 57 84

c

0

(S

0

a

o

c

a

c

a

m

u

0

O

n

CD

IS

V

w

c

0

0

>

I .

ID

V

0

c

Fig .23h Meanpercentagevolumeof larvae

taken

by the

five

clans (+ 2 s.e.)


30

0

D

0

>

20 -

c

(d

u

0

OJ

0)

c

d

CD

u

0

>

c

d

CD

0

d

CD

0

w

c

0

I

X

0

>

9

M

ID

56


67/95

F i g .23i Percentage occurrence of cereal Fig.

3]

Mean percentage volume of cereal

taken by the five clans taken by the five clans (+ 2 s.e.)

(number

above

bars represents sample size) (number

above

bars represents sample size)

7

110 103 67

c c

c

a

d

m

CQ

>

u

L

0

0

>

Q

a

a

V

E

ca

0

V

n

c

0

I

0

>

V.

0

a

0

H

8

5 ^

0

l (

0

2

_

I I

18

C

d

CD

>

u

9

C9

0)

C

(S

CD

0

>

c

0

0

T3

0

I

0

>

u

0

CO

0

K

F i g .

23k Percentage occurrence of wheat Fig. 231 Mean percentage volume of wheat

taken by the five clans taken by the five clans (+ 2 s.e.)

(numberabovebars represents sample size) (numberabovebars represents sample size)

20

0

0

c

0

0

u

0

110 103

c

d

0

a

a

c

a

CD

c

d

03

9)

a

V

d

a

0

V

w

c

0

I

0

0

c

c c

0

>

u

d d d

M

>

0

l

CQ

CD CQ

C

d

0

d

>

u

0

u

(D

o

(1)

d

0

>

0)

I

c

O

U>

E

T3

d

1

57


68/95

F i g .23in Percentage occurrence ofbarley Pig_ 3n Mean percentage volume ofbarley

taken by the five clans taken by the five clans ( 2 s.e.)

(number

above

bars represents sample size) (number

abovebars

represents sample size)

0

u

c c

C

0

d

a

a

a)

>

(S

0

a c

0

>,

u

w

n

0 0 0 0

0 >

a I

a

o

g)

m

0

c c c

2

d d d

0

o

a

c

>,

w

0 0

0 >

o

I

o

0

a

d

(D

58


69/95

F i g .

24a Piggery Bank - Temporal variations in meanpercentageoocunenoeof

each prey

category

during the study pwiod

100

90

w

BO

S 7 0

uuuuumuu^^

m

Hym*nppt*r

p

La rva*

Celaoptara

Ba r thworms

CO

Fig.

24b Badger Bank - Temporal variations in meanpercentageoccurrence of

each preycategoryduring the stiidy period

Ul l l l l l

I

m Hymanoptari

o Larva*

OB

Colaoptara

Caraal

Earthworma

59


70/95

Fig.

24c

River

Bfmk- Ten^raralvariations in mean

peisenu^e

occiinence of

eadi prey category diuing dw studypiod

100

00

80

i

70

60

o

50

o

S

40

i

30

20

10

0

on

Hymnept r10mm and prey 10mm) and

significantlyless

of the smaller

preysizes(10mm. This

suggests

that thebadgerswere selecting against

thesizesthat were most commonly available to them. Fig. 29b shows that the

only

size

classof larvae taken by thebadgersis >10mm despite the

availability

in the habitat of

smaller larvae. Fig.29c shows that most Hymenoptera available in the habitat are in the


79/95

T A B L E

8.Correlations between percentage occurrence ofdifferentprey types in the

diet.

(* = P < 0.05)

R E G R E S S I O N L I N E

E Q U A T I O N

C O L E O P T E R Avs.

H Y M E N O P T E R A

y

= -3.77 + 0.36x

0.301

C O L E O P T E R A

vs.

L A R V A E

y

= 3.04+

0.1 Ix

0.028

C O L E O P T E R A

vs.

C E R E A L

y74.66 - 2.80x

0.585

C O L E O P T E R A

vs.

E A R T H W O R M S

y= 2.67 + 0.59x

0.425

H Y M E N O P T E R A

vs.

L A R V A E

y

= 30.20 - 4.41x

0.391

H Y M E N O P T E R A vs.

C E R E A L

y= 47.65 + 1.99x

0.642

H Y M E N O P T E R A vs.

E A R T H W O R M S

y= 30.12-3.80x

0.422

L A R V A E

vs.

C E R E A L

y

= 46.77 + 1.66x

0.433

L A R V A E

vs.

E A R T H W O R M S

y

= 46.77 + 1.66x

0.343

C E R E A L

vs.

E A R T H W O R M S

y= 107.14-1.71x

0.911*

69


80/95

T A B L E

9.Correlations between

percentage

the diet and the habitat utilisation os badger.pdf

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