Badgers, Meles meles, discriminate between neighbour, alien and self scent

For group-living animals, the ability to discriminate between familiar individuals and strangers may allow reduced agonistic behaviour between holders of neighbouring territories, termed the ‘dear enemy’ effect. We tested the hypothesis that Eurasian badgers can discriminate between self-, neighbour- and alien- (unknown) group faeces placed near their main sett. We carried out a series of controlled field experiments over a 12-month period at the main setts of three badger groups occupying contiguous territories. The experimental design used two different treatments: ‘alien treatment’ involved the display of self-group scents with alien-group scents and ‘neighbour treatment’ involved the display of self-group scents with neighbour-group scents. Badgers showed heightened behavioural responses towards alien- compared with self-group scents, but there was no significant difference in response to neighbour- relative to self-group scents. The relative responses towards alien-group scents were greatest during the breeding seasons, but there were no significant seasonal differences in the responses to neighbour-group versus self-group scents. In undisturbed badger populations, levels of aggression between neighbouring territory-holders are likely to be kept relatively low through neighbour recognition. However, increased levels of aggression will be shown towards dispersing or itinerant (alien) badgers, especially during periods such as the breeding season when the potential threats to the long-term fitness of territory owners are greatest. This behaviour may reduce the effectiveness of management strategies involving the culling of group-living wildlife hosts to reduce levels of livestock or human disease.