Subspecies affiliation and population status of rhesus macaque in Qinghai, China

The rhesus macaque (Macaca mulatta) is the only non-human primate species currently living in Qinghai Province, distributed solely in the southern forest areas of Yushu and Guoluo Zang Autonomous Prefectures. Identifying the subspecies of wild macaques in Qinghai, understanding their population dynamics, and distribution is of great significance for their conservation. In January 2021, one muscle tissue (Baizha, Yushu) and six fecal samples (Makehe, Guoluo) of rhesus macaque were collected by non-invasive sampling, and a phylogenetic tree was constructed using the 16S rRNA and Cyt b genes. It confirmed that the rhesus macaques distributed in Yushu and Guoluo were the Tibetan subspecies (M. m. vestita) and the Sichuan subspecies (M. m. lasiotus), respectively. From January 2021 to May 2023, infrared camera monitoring yielded 91 present sites and 838 independent events of rhesus macaque. Using MaxEnt modeling, the suitable habitat area for macaques was predicted to be 137 - 385 km² (Baizha) and 207 - 750 km² (Makehe). The results indicated that rhesus macaques preferred the habitat of lower altitude, sloping, river-adjacent, sunny forests and farmlands. Transect surveys and random encounter model were used to estimate the macaque population. Following repeated transect surveys in winter 2021 and 2022, conducting at historical record sites (Baizha and Jiangxi in Yushu, Makehe in Guoluo), a total of 24 macaque groups with approximately 1 580 individuals were recorded, with an increase of 43.8% in individuals compared to 40 years ago. The random encounter model estimated the macaque population in Baizha and Makehe to be 73 - 205 and 413 - 1 497 individuals, respectively. The research can provide references and technical support for biodiversity conservation in Qinghai Province.