Distribution and Population Densities of Diurnal Primates in the Karst Forests of Phong Nha-Ke Bang National Park, Quang Binh Province, Central Vietnam

摘要

We studied the status and distribution of the diurnal primates in the Phong Nha - Ke Bang National Park (PNKB NP) from April to August 2007. In the past, researchers reported 9 primate species and subspecies for the karst forests of PNKB NP, which constitutes the most important protected area for the endangered Hatinh langur (Trachypithecus hatinhensis) in Vietnam. All 9 primate taxa are threatened due to hunting pressure and habitat loss. We applied line transect sampling in 4 areas. During a total of 117 transect inspections along 12 different transect routes, we confirmed 5 primate taxa and the analysis of population densities resulted in 2143 (+/- 467) Hatinh langurs, 1316 (+/- 871) red-shanked douc langurs (Pygathrix nemaeus), 930 (+/- 489) stump-tailed macaques (Macaca arctoides), 986 (+/- 883) eastern Assamese macaques (M. a. assamensis), and 18 (+/- 18) southern white-cheeked crested gibbons (Nomascus siki) in the whole PNKB NP, which covers an area of ca. 85,000 ha. We could not detect the 2 nocturnal lorises, Bengal slow lorises (Nycticebus bengalensis) and pygmy slow lorises (N. pygmaeus), as well as rhesus macaques (Macaca mulatta) and northern pig-tail macaques (M. leonina). The distribution of the primates predominantly depended on human impact. We could not recognize a correlation between habitat constitution and abundance of primates. The population density estimates showed a much higher density of the Hatinh langur than previously assumed. Thus the importance of the PNKB NP for the conservation of this endangered langur increased significantly.