Chemosensory discrimination of identity and familiarity in koalas
Benjamin D. Charlton
School of Biology and Environmental Science, University College Dublin (UCD), Belﬁeld, Dublin 4, Ireland
Despite numerous descriptive accounts of scent marking in marsupials, rigorous experimentation is rare, and relatively little evidence exists to show that conspeciﬁcs use chemical signals to distinguish between individuals or different social groups. In this study a series of olfactory discrimination tests sought to determine whether:(1)male koala sternal scent gland secretions are individually distinctive; and (2) male koalas can differentiate between the scent of familiar and unfamiliar individuals. In the ﬁrst experiment a habituation–discrimination trial demonstrated that male koalas discriminate between the scent gland secretions of different unfamiliar individuals. In a second experiment male koalas spent signiﬁcantly more time investigating scent from unfamiliar males than familiar males, supporting the hypothesis that they differentiate between conspeciﬁcs based on their familiarity. Taken together these results suggest that male koalas are able to discriminate the identity and familiarity of conspeciﬁcs using chemical cues, and provide a platform for further studies investigating the functional role of olfactory communication in this species.