Coping with Fragmented Forests: The Critically Endangered Tonkin Snub-Nosed Monkeys (Rhinopithecus avunculus) in Viet Nam

Abstract

The Tonkin snub-nosed monkey Rhinopithecus avunculus is a critically endangered colobine whose current distribution is largely restricted to tropical evergreen forest patches associated with karst limestone hills and mountains of northern Viet Nam. Five isolated extant populations have been identified since its rediscovery in 1992. The fragmentation of its habitats has primarily been the result of decades of expanding human population and increasing demands for scarce agriculturally lands. Habitat fragmentation has frequently been identified a major cause for declines of primate populations, including the Tonkin snub-nosed monkey. However, given that habitats of known Tonkin snub-nosed monkey populations were long fragmented prior to a pioneering study in 1993, the population decline over recent decades can likely be attributed to hunting activities. Comparative observations at two sites suggest that the Tonkin snub-nosed monkey, if effectively protected, is likely to persist for decades in small isolated, undisturbed forest fragments of even just 10 km². In addition, isolated forest fragments should be regarded as important refuges for biodiversity conservation, particularly in regions where little forest remains.