White-tailed deer tarsal glands: sex and age-related variation in microbial flora

The tarsal glands of white-tailed deer (Odocoileus virginianus) are importa nt in the dissemination of socially significant odours. The structure of th e tarsal tufts, associated glandular secretions, and frequent urine deposit ion provide a favorable environment for bacterial growth. We characterized the bacterial flora associated with the tarsal tufts and compared it to the flora from a region with lower glandular activity and no urine contaminati on (mid-back). We identified 24 species of bacteria, 11 of which were speci fic to the tarsal region. The average number of species on the tarsal gland was higher in males than females (P = 0.04) and higher on the tarsal gland than the back (P = 0.10) for both sexes. Species composition also varied a mong sex and age classes. The bacterial composition and species richness of the tarsal tufts suggests that this area is a suitable environment for mic robes responsible for odour production. In particular, we found Corynebacte rium xerosis, a microbe known to convert steroids to more odourous metaboli tes in humans, on the tarsal glands and backs of both sexes of deer. Our re sults are consistent with the hypothesis that microbes associated with the tarsal tuft are important in odour production and that these microbes may t ransform reproductive steroids excreted in the urine into odours that refle ct an animal's social status or reproductive condition.