Ecology and Conservation Status of the black-shanked douc (Pygathrix nigripes) in Nui Chua and Phuoc Binh National Parks, Ninh Thuan Province, Vietnam

The importance of understanding determinants underlining distribution, abundance, social organization and feeding ecology of animal has become increasingly vital to develop either appropriate in-situ or ex-situ conservation plans for endangered species. This study applied ecological and socioecological models to determine the habitat preferences, social organisation and feeding ecology of the black-shanked douc (Pygathrix nigripes Milne- Edwards, 1871), an endangered primate with a restricted distribution in southern Vietnam and eastern Cambodia. Using a systematic survey this thesis provides the first evaluation the distribution patterns of the black-shanked douc; the first assessment of social structure, home range and feeding ecology of the species in Nui Chua and Phuoc Binh National Parks. This thesis also provides the first model to predict the potential of occurrence of a regional douc population in Ninh Thuan Province. This study found that the black-shanked douc distributed at a wide range of elevation from sea level to as much as 1,500 m and in various vegetation types including mixed coniferous/broadleaf forest, sub-montain evergreen forest, sclerophyll evergreen forest, mixed bamboo/broadleaf forest, semi-deciduous forest, deciduous forest, scrubs and thorny woodland. The black-shanked douc preferred foraging on trees growing in a gully area or along streams. The species also avoided areas which did not support its locomotion or provide food, or which was too close to human habitation. Its distribution was associated with the season and influenced by steepness, position on landscape, the nearest distance to a water source and vegetation types. The results also revealed that abiotic factors generally influenced indirectly the distribution of the douc through the distribution of food patches. Demographic data from Nui Chua and Phuoc Binh NPs showed a large population of the black-shanked douc. The minimum number recorded in Nui Chua and Phuoc Binh NPs was 470 and 163 respectively. Within populations, the proportion of immature was higher than mature. The doucs live in groups with mean of group size in Nui Chua and Phuoc Binh populations were 13.06 ± 9.60 and 10.13 ± 5.03 respectively. The species exhibited a flexible organization of one male unit and the band. The proportion of female in groups as well as in populations outweighted that of males with a typical sex ratio numbering two females to one male. The effects of ecological factors on social structure of the species were not confirmed. However, fission of groups may occur due to mating competition. Mean home range estimated for three groups of the black-shanked douc ranged between 30 and 50 ha. Comparison of home range between two different group sizes did not differ significantly. Mean of daily path length was 952 ± 228 m. Groups that lived in low quality forest travelled significantly longer distances than groups that lived in high quality forest. Activity patterns of the black-shanked douc were typical to colobines. The species spent more time feeding and moving in early morning and late afternoon and more time resting from 11:00 to 14:00. The activity budget was associated with day light hours and seasons. In the dry season, the doucs increased time feeding and reduced time resting while they reduced time feeding and increased time resting in the rainy season. Activity budget was not significantly different either between males and females or between adults and juveniles. The black-shanked douc ate 152 plant species. They consumed leaves from 117 plant species, fruit from 42 species, flower from 17 species, seeds from 11 species and petioles of one species. The diet of the black-shanked douc comprised 54.6% of leaves, 29.34% of fruits, 14.56% of flowers and 1.51% other. Type of food consumed was significantly associated with day light hours, months and seasons. The black-shanked douc consumed more fruits and fewer flowers in the morning and less fruits and more flowers in the afternoon. They also ate more fruits in the rainy season and more leaves and flowers in the dry season. This study also found that, the black-shanked douc may broadly distribute in Ninh Thuan Province. A model of potential habitat predicted the doucs may occur in around 76,000 ha and about 30000 ha (less than 10% of the total area) probably has a probability of occurrence of over 50% based on physical site characteristics. Forests of Ninh Thuan Province may support 2600 to 5900 douc individuals. However, the biggest problem was that suitable habitat was fragmented. The large forest remnants act as sink for recolonisation of small forest patches and the metapopulation of the douc in Ninh Thuan Province may maintain themselves if suitable management plans are applied