Does anal gland scent signal identity in the spotted hyaena?

Recognition requires the existence of distinct cues and the ability to detect and discriminate between these signals. Using gas chromatography–mass spectrometry, we investigated the chemical composition of 143 anal scent gland secretions from 84 individually known spotted hyaenas, Crocuta crocuta, in three clans in the Serengeti National Park, Tanzania. In total, 252 volatile compounds were detected. Comparison of the chemical composition of individual scent profiles by calculating the Bray–Curtis similarity index and using an analysis of similarities revealed that scent profiles varied significantly between individuals but also changed in composition over time. There was no difference in complexity, in terms of the number of different compounds, between male and female scent or between scent from high- and low-ranking females. Scent profiles of closely related females were as similar as profiles of unrelated females. Although there was no evidence of rank-related changes in profiles across the entire female social hierarchy, the profiles of high-ranking females differed significantly from those of low-ranking females, suggesting the presence of an olfactory badge of status. Behaviourally, adult females responded to scent deposited on vegetation by other females significantly faster and more often, and were more likely to anoint themselves with that scent, as the social rank of the female who had deposited the scent increased. These results suggest that spotted hyaena scent carries both an olfactory badge of status and individually distinct cues that are likely to be useful in the maintenance of a social network within their fission–fusion society.