Western Purple-faced Langur
Encyclopedia
The western purple-faced langur (Trachypithecus vetulus nestor), also known as the north lowland wetzone purple-faced langur, is a subspecies of purple-faced langur
endemic
to Sri Lanka
. It lives in the wet zone in western Sri Lanka around the former capital city of Colombo
. The subspecies is generally gray-brown with lighter whiskers, a gray rump patch, and dark forearms and legs. Typical length is between 48 and 67 cm (18.9 and 26.4 in) excluding tail, with a 59 to 85 cm (23.2 to 33.5 in) tail. On average, males weigh 8.5 kilograms (18.7 lb) and females weigh 7.8 kilograms (17.2 lb).
Since 2004, it has been considered to be critically endangered by the International Union for Conservation of Nature (IUCN) due to an 80% decline in population over the previous 36 years, and the fact that the rate of population decrease is expected to continue unabated. Prior to 2004 it was listed as "endangered", but not "critically endangered". In 2010, the western purple-faced langur was included in the list of The World's 25 Most Endangered Primates
, published by the IUCN and other organizations.
Reasons for the subspecies' critical endangerment are largely due to deforestation. Studies have estimated that 81% to over 90% of the subspecies' former range has been deforested. Deforestation harms the monkey in several ways. The western purple-faced langur is naturally folivorous, and its biology is specialized for a diet that consists primarily of leaves. With leaves less available, the monkey's diet consists largely of cultivated fruit taken from people's gardens. This has several detrimental impacts on the monkey - it may not be able to extract adequate nutrition from fruit which it is not biologically adapted to use as a primary food source and the food is only available seasonally, leaving inadequate nutrition outside of fruiting season. Since the western purple-faced langur is naturally arboreal, deforestation also impacts its activities besides eating. With less forest available, monkeys spend more time than is natural on the ground, exposing them to danger from domestic dogs and cars, and they also climb power lines, exposing them to danger of electrocution. Also, when the monkeys are on the ground, they are easier to capture for the pet trade. Hunting is also a concern.
Hope for the subspecies continued survival comes from the fact that the largest forests that it currently inhabits are around important water reservoir
s and thus less likely to be exploited for other purposes. Also the Sri Lanka Forest Department is undertaking a project to promote forest conservation.
Purple-faced Langur
The purple-faced langur , or purple-faced leaf monkey, is a species of Old World monkey endemic to Sri Lanka.This is a long-tailed arboreal species, mainly brown with a dark facemask and paler lower face...
endemic
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...
to Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
. It lives in the wet zone in western Sri Lanka around the former capital city of Colombo
Colombo
Colombo is the largest city of Sri Lanka. It is located on the west coast of the island and adjacent to Sri Jayawardenapura Kotte, the capital of Sri Lanka. Colombo is often referred to as the capital of the country, since Sri Jayawardenapura Kotte is a satellite city of Colombo...
. The subspecies is generally gray-brown with lighter whiskers, a gray rump patch, and dark forearms and legs. Typical length is between 48 and 67 cm (18.9 and 26.4 in) excluding tail, with a 59 to 85 cm (23.2 to 33.5 in) tail. On average, males weigh 8.5 kilograms (18.7 lb) and females weigh 7.8 kilograms (17.2 lb).
Since 2004, it has been considered to be critically endangered by the International Union for Conservation of Nature (IUCN) due to an 80% decline in population over the previous 36 years, and the fact that the rate of population decrease is expected to continue unabated. Prior to 2004 it was listed as "endangered", but not "critically endangered". In 2010, the western purple-faced langur was included in the list of The World's 25 Most Endangered Primates
The World's 25 Most Endangered Primates
The World's 25 Most Endangered Primates is a list of highly endangered primate species selected and published by the International Union for Conservation of Nature Species Survival Commission Primate Specialist Group , the International Primatological Society , and Conservation International...
, published by the IUCN and other organizations.
Reasons for the subspecies' critical endangerment are largely due to deforestation. Studies have estimated that 81% to over 90% of the subspecies' former range has been deforested. Deforestation harms the monkey in several ways. The western purple-faced langur is naturally folivorous, and its biology is specialized for a diet that consists primarily of leaves. With leaves less available, the monkey's diet consists largely of cultivated fruit taken from people's gardens. This has several detrimental impacts on the monkey - it may not be able to extract adequate nutrition from fruit which it is not biologically adapted to use as a primary food source and the food is only available seasonally, leaving inadequate nutrition outside of fruiting season. Since the western purple-faced langur is naturally arboreal, deforestation also impacts its activities besides eating. With less forest available, monkeys spend more time than is natural on the ground, exposing them to danger from domestic dogs and cars, and they also climb power lines, exposing them to danger of electrocution. Also, when the monkeys are on the ground, they are easier to capture for the pet trade. Hunting is also a concern.
Hope for the subspecies continued survival comes from the fact that the largest forests that it currently inhabits are around important water reservoir
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
s and thus less likely to be exploited for other purposes. Also the Sri Lanka Forest Department is undertaking a project to promote forest conservation.