The Purple-faced leaf langur (Trachypithecus vetulus) has been listed as Critically Endangered by the World Conservation Union (IUCN) and one of the world’s top 25 most endangered primates. This species is endemic to Sri Lanka and strictly protected under the flora and fauna protection ordinance (Amendment) Act No. 22 of 2009 of Sri Lanka. In Sinhala, this species is called ‘Kalu Wadura’ and classified under the group of old-world monkeys.
The color of their coat is generally brownish-black on the body and limbs, whilst the facial whiskers range in colors from white to pale brown and are directed backward. The face is grayish-black, as opposed to purple as its name suggests. Over 90% of purple-faced langur’s habitat has been deforested, forcing them to live alongside human communities in gardens and on rooftops. Ideally, leaves make up around 60% of the langur’s diet with fruits and flowers. Now their diet becomes heavily dependent on cultivated fruits, that grow on farms and gardens.
Purple-faced langur requires a good canopy cover. Arboreal animals like the purple-faced langur are unwilling to crossroads and large patches of bare ground. Therefore, when a forest is physically cut off from other habitats, it becomes like an island( isolated place ) to some of the inhabitants. The human settlement, hunting, trade, habitat loss, encroachment for agriculture, plantation, and human habitations are main threats against the langurs. According to the data, during the 42-year period (1956- 1993), the country has lost 50% of its forest cover, and more than 50% of it’s during the subsequent 10 years (1994- 2003). It is found a 1:1 relationship between loss of critical habitat and population number.
The killing of langurs by humans is rear and they died because of poaching, road accidents, and killing by residents’ dogs. When deforestation increased and forced them to move on the ground, it was hardly adapted to them. People sometimes capture young individuals to raise them as house pets. The mortality of the langurs is common due to electrocution. It also has been recorded that, langurs are killed for their skins.
Purple-faced langurs are shy animals by their nature making them difficult for researches to study. Habitat management, government education, public education, researches(Taxonomy, Genetics,behaviour, ecology and surveying) can use as conservation actions for protect this endemic most endangered primate.
Article by P.A.S.Hasangika
( B.Sc. , RUSL )
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