Rhinopithecus bieti at Xiaochangdu, Tibet: Adaptations to a Marginal Environment

Abstract

Understanding the ways in which primates have adapted to tolerate harsh environments, such as temperate forests found at high altitudes with extreme variations in temperature and food supply, may help us to understand the persistence of particular primate species when many others are in decline. In this chapter, I review the main results from the study of the ecology and behavior of an endangered monkey (Rhinopithecus bieti) in a harsh environment at Xiaochangdu, Tibet. The monkeys varied their diet throughout the year to cope with strongly seasonal food availability. They prefer to feed on leaves or fruit whenever they can be obtained, suggesting that lichens serve as a staple or a fallback food, not the resource of choice for this population. They had longer daily travel length (DTL) in summer and spring than in winter. The behavioral responses of the group were site-specific to the temperate zone and generally in accordance with current theories of primate ecology that both travel requirements to find fruit and the time and energy available for traveling increase as the proportion of fruit in the diet increases. The monkeys ranged at elevations between 3,550 and 4,300 m; however, they did not generally prefer any particular altitudinal zone. This vertical ranging behavior may be a site-specific phenomenon resulting from peculiarities of the monkeys’ habitat such as human disturbance patterns. Mating events occurred between July and October; births occurred between February and mid-March. Variation in food availability, temperature, and photoperiod may be ecological influences on the timing of reproductive events.