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Monitoring badgers and red foxes
Journal
Mammal Review, Volume
34, Numbers 1-2, January 2004, pp. 75-98(24) -
Blackwell Publishing
Authors
SADLIER L.M.J.; WEBBON C.C.; BAKER
P.J.; HARRIS S.
Abstract
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A national monitoring scheme for recording the
abundance of foxes and badgers in Britain would have to utilize a
technique or techniques that could detect a wide range of animal
densities in structurally different habitats. Furthermore, the likely
reliance on volunteers for data collection means that these techniques
must be easily applied by people with different levels of field
expertise.
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Direct methods that rely on counts of the animals
themselves (e.g. capture-mark-recapture, radio-tracking, spotlight
counts) are generally unsuitable because of cost, manpower and licensing
requirements, are not readily applied to all habitats and cannot easily
be used by volunteers. However, density estimates derived from
capture-mark-recapture and radio-tracking methods are likely to
represent the benchmark against which other estimates of abundance are
measured.
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The number of foxes killed per unit area is
currently collated by non-governmental organisations for some patterns
of land use, e.g. game estates. No such data are available for badgers,
as this species is legally protected in Britain. However, the
applicability of hunting statistics for monitoring fox abundance is
limited by differences in culling effort, the non-independence of
different culling practices applied in the same region, possible future
changes in the legal status of different culling methods and changes in
the ratio of land where foxes are and are not culled.
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Indirect methods that rely on counts of the signs of
the animals (e.g. droppings, breeding refugia) are less expensive than
direct methods, can be applied to the range of habitats found in Britain
and can easily be used by volunteers. To date, indirect methods have
been utilised to derive estimates of relative animal density or the
density of social groups. However, the major factor currently limiting
the use of indirect methods is that their relationship with absolute
animal density has not been validated. The preliminary results of two
projects quantifying the use of field signs as a measure of absolute fox
and badger abundance suggest that indirect methods could be applicable
for monitoring changes in fox and badger numbers at a national scale.
Keywords
badger; fox; monitoring; sign surveys
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