The Purple - Faced Langur is an Old World monkey endemic to Sri Lanka. They are long-tailed, arboreal, mostly brown species with a dark face and a very shy nature. They live in closed canopy forests in Sri Lanka's mountains and the southwestern part of the country, known as the "wet zone". They are mostly folivorous, but will also feed on fruits like Dimocarpus longan and Drypetes sepiaria, flowers, and seeds. While they normally avoid human habitations, fruit such as jak, rambutan, banana, and mango may contribute up to 50% to their diet in cultivated areas. Their digestive tract, with its specialized stomach bacteria, has evolved to derive the majority of their required nutrients and energy from complex carbohydrates found in leaves. Males are usually larger than females and both have black to grayish brown coats, and whitish to gray short 'trousers' rounded off by purplish-black faces with white sideburns. Part of the back is covered with whitish fur, and tail is also furred with black and white mixed colors. Feet, and hands are also purplish-black in color. They use vocalization to alert members of predators, attract mates, defend territory, and locate group members. Like humans, adult males are the most vocal among the entire group and their defensive whooping calls are also accompanied by intense visual and locomotive displays. Their range has constricted greatly in the face of human encroachment, although it can still be seen in Sinharaja, Kitulgala, Kandalama, Mihintale, in the mountains at Horton Plains National Park or in the rainforest city of Galle. Populations are critically low within and between sites. Threats to this species include infringement on range by croplands, grazing, changing agriculture, road production, soil loss/erosion and deforestation, poisoning from prevention of crop raiding, and hunting for medicine and food.