Responses of foraging hedgehogs to badger odour

Enclosure and field trials were used to investigate the responses of hedgehogs, Erinaceus europaeus, to predator (badger,Meles meles) and non-predator odours. Two hypotheses were tested: (1) hedgehogs are capable of responding to badger odour; and (2) hedgehogs prefer not to forage in areas tainted with badger odour. In enclosure trials, hedgehogs almost exclusively avoided feeding at sites tainted with badger faeces in favour of sites tainted with non-predator faeces, and continued to avoid the previously badger-tainted site after 2 days, but not after 4. Field experiments with free-ranging hedgehogs showed a reduction in foraging effort in response to badger odour over periods of 5 and 30 min, but no evidence of site avoidance over a 24-h period. Lack of persistent avoidance of badger odour in the field was probably due to the costs of predator avoidance, which were negligible in the enclosure owing to the presence of an alternative superabundant food source. ? 1997 The Association for the Study of Animal Behaviour Where predators are a significant cause of mortality, selection will act to favour prey that can recognize and avoid their predators. The prey may use visual or auditory cues to anticipate direct attack, but they may also detect indirect cues to the presence of predators in order to avoid encounters. Amongst nocturnal mammals, odour is an important means of signalling and communication. Its use provides an opportunity for prey species to reduce their probability of being eaten by recognizing the odorous evidence of their predator’s presence (see review by Weldon 1990). For many prey species, their behavioural responses to this perceived threat of predation are known to influence their local patterns of distribution with respect to the distribution of predators (see review by Lima & Dill 1990), although costs associated with predator avoidance, such as reduced feeding rates and reduced breeding opportunities (e.g. Sih 1988), may well influence the response to the perceived danger. The local distribution and abundance of hedgehogs in rural Oxfordshire, U.K., correlates 0003–3472/97/040709+12 $25.00/0/ar960307 ? 1 70 inversely with the distribution of badgers (Micol et al. 1994). The result is a patchy distribution of hedgehog populations, and their absence from some areas of their preferred habitat of shortgrass fields, hedgerows and copses. Hedgehogs have a well-defined morphological adaptation to the danger of predation, in the form of their dorsal coat of spines. They are not fast-moving animals, and this armoury appears to suffice as a defence against potential predators such as foxes. Foxes, Vulpes vulpes, living in urban Oxford, where hedgehogs are abundant, will occasionally attack hedgehogs and will scavenge from dead hedgehogs, but this species is present at very low frequency in their diet (Doncaster et al. 1990). However, the spines are not adequate defence against badgers, which are able to force access to the hedgehog’s vulnerable underbelly, and are known to prey upon them when the opportunity arises (Doncaster 1993). Risk of predation from badgers is thus a plausible explanatory factor underlying the observed distribution of hedgehogs. In a study of factors regulating local variation in abundance of hedgehogs, Doncaster (1994) released 50 wild hedgehogs into suitable habitat patches with and without permanent natural populations of hedgehogs. Survival of transplanted hedgehogs was significantly lower at the Correspondence: D. W. Macdonald, Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, U.K. C. P. Doncaster is now at the Department of Biology, School of Biological Sciences, Biomedical Sciences Building, Bassett Crescent East, Southampton, SO96 7PX, U.K. 997 The Association for the Study of Animal Behaviour