An updated assessment of primate fauna in Son Tra Nature Reserve, Danang, Vietnam using an integrated survey approach

Abstract Son Tra Nature Reserve in Danang was established in 1992 to protect important habitats and wildlife in the central part of Vietnam. While Son Tra is known to harbor a significant population of the red-shanked douc, the status and presence of its other primates have remained uncertain. To provide updated data on the presence and distribution of the primates in Son Tra, we implemented a combined methodology of transect and camera trapping surveys. We conducted the transect survey along 12 parallel main transects and complementary routes between 12 April and 05 May 2024. Additionally, we deployed 19 systematic camera-trapping stations from 19 April to 14 August 2024. Our survey recorded the red-shanked douc ( Pygathrix nemaeus ), the southern pygmy loris ( Xanthonycticebus pygmaeus ), the stump-tailed macaque ( Macaca arctoides ), the long-tailed macaque ( Macaca fascicularis ), the pig-tailed macaque ( Macaca leonina ), and the rhesus macaque ( Macaca mulatta ). However, supporting evidence suggest it is likely that only three species (the red-shanked douc, the southern pygmy loris, and the rhesus macaque) naturally occur in Son Tra. The three remaining macaque species likely originated from illegal wildlife trades and improper releases. Our results will help conduct proper conservation measures to better protect the native primates in Son Tra.