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

The tarsal glands of white-tailed deer (Odocoileus virginianus) are important in the dissemination of socially significant odours. The structure of the tarsal tufts, associated glandular secretions, and frequent urine deposition 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 contamination (mid-back). We identified 24 species of bacteria, 11 of which were specific 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 among sex and age classes. The bacterial composition and species richness of the tarsal tufts suggests that this area is a suitable environment for microbes responsible for odour production. In particular, we found Corynebacterium xerosis, a microbe known to convert steroids to more odourous metabolites in humans, on the tarsal glands and backs of both sexes of deer. Our results are consistent with the hypothesis that microbes associated with the tarsal tuft are important in odour production and that these microbes may transform reproductive steroids excreted in the urine into odours that reflect an animal's social status or reproductive condition.