The black-shanked douc (Pygathrix nigripes) is an endangered species of douc found mostly in the forests of eastern Cambodia, with some smaller populations in Vietnam. This species is unique among the doucs in having a largely greyish-blue face. No global population estimate exists, although the Wildlife Conservation Society report an estimated 23,000 individuals present in Cambodia's Keo Seima Wildlife Sanctuary. Prior to the discovery of the significance of this population, the largest populations were believed to be in adjacent Vietnam, where the largest known population is around 500-600 individuals. They are primarily arboreal and their diet consists on leaves, of which they obtain most of their water.