The role of bacteria in mediating social cohesion in spotted hyena groups, through the pungent odours they generate, is investigated in a paper published in Scientific Reports this week.
Spotted hyenas live in clans - complex social groups of about 40-80 individuals. They use various tactile, visual, vocal and chemical signalling behaviours to mediate social relationships within and among clans. A common example is ‘pasting,’ a form of scent marking in which a hyena leaves a sour-smelling secretion (‘paste’) on grass stalks. The strong odour is probably a by-product of bacterial fermentation, and it has been suggested that spotted hyenas’ group-specific social odours result from the group-specific bacterial communities that live in their scent pouches, but technical limitations have made it difficult to test this hypothesis.
Using next-generation molecular sequencing techniques, Kevin Theis and colleagues analyzed the bacterial communities inhabiting the scent pouches of 16 female spotted hyenas from four clans. They report a high degree of microbial diversity and show that microbial communities tend to be more similar among hyenas from the same clan than those from different clans.
The research shows that spotted hyenas’ scent pouches harbour diverse communities of fermentative bacteria, whose close relatives are known odour-producers, and that the odours they produce are the same as those shown to constitute group-specific social odours among hyena clans. But although the study suggests this microbial diversity is sufficient to underlie group-specific odours in this animal, further research is needed to definitively show that the odour and bacterial profiles of individual paste samples co-vary.