New distribution records for the endangered black-and-white snub-nosed monkeys (Rhinopithecus bieti) in Yunnan, China

Abstract. Black-and-white snub-nosed monkey (Rhinopithecus bieti) is an IUCN-Endangered primate endemic to China. There are currently 15 groups separated into five units based on genetic and geographic character analysis. Among these, the southern groups being on the species' most marginal distribution is the most susceptible to extinct in the near future due to most forest fragmentation and human activities. To determine the population dynamics and conversation needs in the southern unit, we conducted interviews and investigation-based interviews in Yunlong and Lanping Counties from December 2013 to February 2018. A new group contains approximately > 10 members, Tianchi group, was found in Tianchi National Nature Reserve and a known group with approximately > 20 R. bieti individuals, Heishan group, which had historically disappeared, was rediscovered in Yunling National Nature Reserve in the southern unit. As a consequence of this survey, the number of groups in the southern unit has increased from three to five, and the total groups has increased from 15 to 17, and the Tianchi group has become the southernmost group and totally isolated group with irreplaceable conservation value. These results indicate that R. bieti groups in the species' southern distribution range may be undergoing recovery and that nature reserves are playing a critical role in conservation efforts. However, small group size, highly fragmented habitats, and marginal distribution in reserves mean that these two groups are still vulnerable to extinction. We accordingly make recommendations and propose management policies for their protection: the Chinese government should commit to protect the new groups by funding academic research and conservation; the reserves, conservationists, and NGOs should take appropriate actions to ensure the establishment of long-term survey and monitoring programs.