Analytical Chemistry

Dr. Lee Hagey

Olfactory communication is well developed in Giant Pandas, which have specialized glands used for scent marking. Residues from these glands are left behind on trees and rocks, which serve as message boards for nearby pandas. The scent marks are semi-volatile, and can persist in the environment for some length of time. In general, males possess better developed glands and mark more frequently. It is believed that in both sexes, scent marks have the potential to advertise home range occupation, facilitate navigation, attract mates, threaten or warn conspecifics, signal individual identity, reproductive state, dominance status or mood. Olfactory communication may be especially important for a solitary species like the panda, which has a very brief estrus period and where sustained social contact is rare.

The Division of Analytical Chemistry of the Center for Reproductive of Endangered Species (C.R.E.S.) has begun the process of both collecting scent marks and determining their chemical contents. The male scent mark is a mixture of fifteen major volatile chemical compounds mixed in with a waxy matrix that serves to delay and slow evaporation of the scent. The female scent mark is a watery mixture of over 100 major volatile compounds, most of which rapidly evaporate. An examination of scent glands, vaginal smears, and urine indicate that scent marks from males consist of scent gland material, whereas those of females consist primarily of urine. Thus, females and males may be using fundamentally different strategies to advertise their presence. Male scent marks are very likely perimeter markers, and must last long enough for the males to make a complete circuit of their home territories. In females, the rate of scent marking is normally low, but undergoes a burst of activity shortly before they enter estrus. It is very likely that hormonal metabolites in female urine sends a rapidly decaying but current status report message to males on their availability for mating.

The laboratory has also swabbed various areas of a panda's body and environment to determine what types of scents a panda might focus on. In analyzing these swabs, it is possible to develop scent maps which depict the location of various compounds on a panda's body. In typical pandas, oily skin secretions are found along the animals dorsal surface, while urine and scent mark components are found around the anogenital region. The same chemical components are found on the back of the paw as are found around the eyes. Males differ from females in that the predominant component on male ears is urine; with females the dominant component is plant material.

This diagram shows the scent map of a male panda. Different scents accumulate on different parts of the male's body and environment: blue areas represent those areas where scent mark material can be found; yellow areas represent areas where oily secretions predominate; green areas indicate that the animals use only the back of their paws to rub their eyes; orange areas are where urine is found. It is suspected that males rub urine on their ears because the black, heat emitting ears can assist in releasing important urine scent components into the environment.