Developing an oral bait for badger vaccination - Exeter Research ...

asic and grouped estimates of habitat as a proxy for available natural food resources is not a
reliable indicator for predicting bait disappearance. A more detailed and current estimate of actual
food availability in each territory would be required to determine if natural food abundance
significantly influences bait disappearance.
As the estimated number of badgers in a social group increased investigatory behaviour towards
baits and attempts to retrieve baits increased as did bait disappearance. Larger groups of animals
are likely to have greater levels of intraspecific competition, especially if natural resources are low,
and therefore may take baits more readily. It is also hypothesized that one advantage of group living
is the opportunity to share information and learn from other group members (Clark & Mangel,
1986). Groups of animals can act as “information centres”, where individual animals can enhance
their feeding success by following more successful animals to sources of food, for example terns that
returned to the colony with a fish, were more likely to be followed on subsequent trips (Waltz,
1987). Studies by Kruuk (1978) on natural foraging reported that badgers were only seen foraging in
groups very rarely and that it was unlikely that badgers gained foraging experience by learning from
each other. However learning behaviour has not been investigated for manmade baits disturbed on
or around setts, and could explain the increased disappearance of baits in groups with more
individuals. It must be noted that the results could also just be a product of more animals resulting in
a greater bait encounter probability.
There was an increase in (i) bait disappearance (Fig. 2), (ii) the number of investigations and (iii) the
number of attempts made to access baits as each study progressed. This is similar to results from
bait disappearance studies with urban foxes which showed as steep increase over the first 2-3 days
before approaching an asymptote (Trewhella et al., 1991). This behviour is suggestive of a neophobic
response to novel food items. Knoble et al. (2002), trialing oral rabies baits for free-ranging African
wild dogs (Lycaon pictus), noted that subordinate African wild dogs often displayed such behviour,
often being seen investigating baits but not ingesting them. They also went on to report increased
pack coverage with increased exposure of the pack to baits, noting how once a dog ingested a bait it
would seldom ignore further baits and would appear to actively search them out. Additionally the
baits trialed during our studies contained ingredients quite different of food types badgers would
find naturally (i.e. contained peanuts, vanilla extract, sweeteners etc) and investigations of sheep
and goat grazing behviour reported that these species typically avoid flavor concentrations that are
most different from what they have eaten in the past (Provenza et al. 1994).
For habituated social groups 52% of the baits available were taken on day one, which increased to
74% on day five and 91% on day 10. In contrast, only 6.8% of baits were taken by naïve badgers in
study 4 over the duration of the 10 day study. The potential implications of 93% of baits being left in
43