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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.
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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
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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.
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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.
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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.
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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.
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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
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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
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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
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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
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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
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Fig .4.
Geology of the studyarea.
N
/K
0 200m
J
Fluvio glacial sand
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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
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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
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(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
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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).
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F i g .8. PiggeryBankSett.
O
Main
badger path
O Sett entrance
Maturetree
Fieldboundary
0
0
0
0
/
/
/
/
0
/0
a
1m
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Fig .
9.
Badger
Bank
Sett.
0
L
1m
o
Main
badger path
3 Sett entrance
1^^^^
Maturetree
Fieldboundary
\
0 -
(
-
o
.0
/
0
--Q
0
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F i g .
10.
RiverBankSett.
Mainbadger path
O
Sett entrance
Maturetree
-**Fieldboundary
Wo;.
\
\
\
\
\
y
1m
1
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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
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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
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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.
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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
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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.
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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.
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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
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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
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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
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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)
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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.)
(numberabove bars represents sample size)
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
(numberabove bars represents sample size)
Fig .
23d
Mean
percentage
volume
of Coleoptera
taken
by the fiveclans (+ 2 s.e.)
(numberabove bars represents sample size)
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
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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.)
(numberabove bars represents sample size)
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
(numberabove bars represents sample size)
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.)
(numberabove bars represents sample size)
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
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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
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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
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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
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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
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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
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T A B L E
9.Correlations between
percentage
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