Scent signals individual identity and country of origin in otters

Signalling individual identity conveys fitness benefits to signaller and receiver, for example by enabling the avoidance of breeding with kin. Chemical analysis indicates that scent marks are used to communicate individual identity in several mammalian species, but prior to the current study there has been no detailed assessment of individuality in otter scent marks despite their widespread use to survey population distributions. Repeated spraint samples were collected from captive Eurasian otters, Lutra lutra, and analyzed using solid phase microextraction and gas chromatography mass spectrometry. Permutational Multivariate Analysis of Variance (PerMANOVA) was chosen over ordination techniques because it uses all of the scent profile rather than a subset of the data. Spraint scent was significantly associated with the identity of the individual otter that deposited it, and the country of origin. Scent similarity between otters at the same location may be explained by genetic similarity. Within-individual variation in scent profiles was also observed which we hypothesize could be explained by hormonal fluctuations. Future research should aim to explain this within-individual variation further and explore other odour signals of individual identity in otters (for example non-volatile compounds).