The Purple-faced langur is an endangered long-tailed arboreal monkey that can be found only in Sri Lanka. It is identified by a mostly brown appearance, dark face (with paler lower face), and very shy nature. Males of this species are usually larger than females.
Purple-faced langurs are found in closed-canopy forests in Sri Lanka's mountains and the southwestern part of the country, known as the "wet zone". Although their range has constricted greatly in the face of human encroachment, Purple-faced langurs can still be seen in Sinharaja, Kitulgala, Kandalama, Mihintale, in the mountains at Horton Plains National Park or in the rainforest near the city of Galle.
Purple-faced langurs are active during the day. They spend their lives in threes and are very territorial. Purple-faced langurs live in groups that usually consist of one adult male, up to 7 adult females, and their offspring of different ages. Some males live in bachelor groups that usually number from 2 to 14 individuals. Purple-faced langurs are very vocal and communicate with each other using various types of calls. Loud calls are often used to distinguish between individual langurs. These include harsh barks, whoops, and residuals. Calls occur more often in the morning mostly stimulated by neighboring groups and territorial battles. More calls occur during sunny periods than cloudy. The fewest calls occur in the evening. Daytime calls usually aid in the defense of home ranges. The loud barking call, particularly of the highland form, can be mistaken for the roar of a predator such as a leopard. Purple-faced langurs vocalize to alert members of predators, attract mates, defend territory and locate group members. Adult males are usually the most vocal among the entire group.
Female Purple-faced langurs give birth to a single infant after the gestation period of 195-210 days. The young are nursed by their mothers for 7-8 months and become reproductively mature at the age of 4 years.
Purple-faced langurs are threatened by habitat loss due to rapid urbanization, infringement on the 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.
The IUCN Red List and other sources don’t provide the number of the Purple-faced langur total population size. Currently, this species is classified as Endangered (EN) on the IUCN Red List and its numbers today are decreasing.