The black-shanked douc (''Pygathrix nigripes'') is an endangered
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
douc
The doucs or douc langurs make up the genus ''Pygathrix''. They are colobine Old World monkeys, native to Southeast Asia, which consists of these 3 species: red-shanked douc, black-shanked douc, and gray-shanked douc.
Description
The doucs ...
found mostly in the forests of Eastern
Cambodia
Cambodia (; also Kampuchea ; km, កម្ពុជា, UNGEGN: ), officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochinese Peninsula in Southeast Asia, spanning an area of , bordered by Thailand t ...
, with some smaller populations in Southern
Vietnam
Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...
. The region they are mostly found in is called the
Annamite Range
The Annamite Range or the Annamese Mountains (french: Chaîne annamitique; lo, ພູ ຫລວງ ''Phou Luang''; vi, Dãy (núi) Trường Sơn) is a major mountain range of eastern Indochina, extending approximately through Laos, Viet ...
, a mountainous area that passes through Cambodia and Vietnam. Its habitat is mostly characterized by evergreen forest in the mountains, in the middle to upper canopy. They move around quadrupedally and by brachiation up in the trees. This species is unique with its coloration among the doucs as it has a bluish face with yellow rings around its eyes a blue scrotum and a pink penis. Like other doucs, this specie has a tail as long as its body and head length. Black-shanked douc have been observed in groups ranging from 3 to 30 indivuals, depending on their habitat. Group tend to have a fission-fusion dynamic that changes with food availability. Their diet varies from dry to wet season. Regardless of the season, their diet consists mostly of leaves, but they have also been found to consume considerable amounts of fruits and flowers during wet season. The species changed conservation status in 2015 from
endangered
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...
to
critically endangered in the
IUCN Red List of Endangered Species
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...
. This reassessment is due to an increase of the rate of population decline. No global population estimate exists.
The majority of the population can be found in Cambodia, with smaller populations in Vietnam. In fact,
Wildlife Conservation Society
The Wildlife Conservation Society (WCS) is a non-governmental organization headquartered at the Bronx Zoo in New York City, that aims to conserve the world's largest wild places in 14 priority regions. Founded in 1895 as the New York Zoological ...
reports a almost 25,000 individuals present in Cambodia's
Keo Seima Wildlife Sanctuary
Keo Seima Wildlife Sanctuary ( Khmer: ដែនជម្រកសត្វព្រៃកែវសីមា) is a protected area of mixed seasonal tropical forest in eastern Cambodia, located in Mondulkiri and Kratié provinces. The area was f ...
, a population that has remained stable over the last decade. The largest populations estimated to be in Vietnam is around 500-600 individuals.
[Unexpected Large Monkey Population Discovered](_blank)
Newswise, Retrieved on August 28, 2008. The biggest challenges that the black-shanked douc faces in terms of conservation are habitat loss and illegal poaching. Conservation efforts are being made to control illegal poaching and trade in Vietnam by putting laws against hunting and trading threatened species.
Geographic range and habitat
Species from the
''Pygathrix'' genus are all Indochina
endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
species, that can be found in
Cambodia
Cambodia (; also Kampuchea ; km, កម្ពុជា, UNGEGN: ), officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochinese Peninsula in Southeast Asia, spanning an area of , bordered by Thailand t ...
,
Laos
Laos (, ''Lāo'' )), officially the Lao People's Democratic Republic ( Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ, French: République démocratique populaire lao), is a socialist ...
, and
Vietnam
Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...
, but the black-shanked douc is only found in Cambodia and Vietnam.
Studies on douc species have shown differentiation in ecological niche.
The findings were that each douc species are spread out from North to South of Vietnam, each having their own latitudinal range. For the black-shanked douc, they estimated its geographic range is at a narrow latitudinal range of 11° N to 13.5°N, in Eastern Cambodia and Southern Vietnam.
They can be found living in different types of forest: broad-leafed evergreen, semievergreen, mixed, dipterocarp lowland.
More specifically, those species of the ''Pygathrix'' genus are mostly found in the
Annamite Range
The Annamite Range or the Annamese Mountains (french: Chaîne annamitique; lo, ພູ ຫລວງ ''Phou Luang''; vi, Dãy (núi) Trường Sơn) is a major mountain range of eastern Indochina, extending approximately through Laos, Viet ...
, a mountainous landscape in Eastern Indochina. Like all douc species, the black-shanked douc is an arboreal species that moves around quadrupedally and through braciation as locomotion.
It is mostly found in the middle to upper forest canopy for most the time.
The range of elevation of the terrain where they have been seen goes from sea level to 1500 meters. However, it is important to note that most the forest at lower elevation have been torn down over the years. Therefore, most sightings occur at higher elevations.
[Rawson, B. M. (2009). ''The socio-ecology of the black-shanked douc (Pygathrix nigripes) in Mondulkiri Province, Cambodia''. Retrieved from https://openresearch-repository.anu.edu.au/handle/1885/49396]
Description
Like all species of ''Pygathrix'', the black-shanked douc is characterized by its colorations. The colors on its head and neck are what differentiates the black-shanked douc from other species of the ''Pygathrix'' genus. Their most unique characteristic is their bluish face with large yellow eye-rings. It also has thin and short whiskers. The outline of its face has a thin chestnut coloration before the back of its head which is black. The region around its throat is white. Its back is dark grey. Its belly is light grey. Their rest of their body is black, which includes legs and arms, excluding the pubic patch area which is white, their scrotum is blue, and their penis is pink. While the majority of individuals have those standard colors, there has been color variations observed in few individuals, who were confirmed by genetic sampling to be black-shanked doucs.
Amongst those observations, color variations occurred for the forearms which were partially or completely white and the lower leg which was dark red.
Though it is not fully understood, an explanation for those color variations would be due to hybrid between douc species.
It has a tail as long as its body and head length. Few individuals were measured but the results for the male black-shanked douc had an average head and body length of 50 cm, an average tail length of 690 cm and an average weight of 5.3 kg. While the female black-shanked douc had an average head and body length of 56 cm and an average weight of 5.4 kg.
Behaviour
Four major social units occur in the species: one-male units, bands comprising several one-male units, bachelor groups and lone males. In a study in
Keo Seima Wildlife Sanctuary
Keo Seima Wildlife Sanctuary ( Khmer: ដែនជម្រកសត្វព្រៃកែវសីមា) is a protected area of mixed seasonal tropical forest in eastern Cambodia, located in Mondulkiri and Kratié provinces. The area was f ...
, one-male units averaged 7.5 individuals, and were composed of a single male, several females and offspring. Their social hierarchy is therefore male dominant. Black-shanked doucs have a fission-fusion social system, with fusion of one-male units into bands occurring more commonly in the wet season due to higher food availability.
Group size can vary from 3 up to 35 individuals.
The reason for such variability in size has been associated with the quality of their habitat and the level of human disturbance. Groups that were observed in the wild were of multi-male, multi-female disposition, with a higher ratio of males, the bigger the group was.
Diet
Black-shanked doucs are mostly
folivorous
In zoology, a folivore is a herbivore that specializes in eating leaves. Mature leaves contain a high proportion of hard-to-digest cellulose, less energy than other types of foods, and often toxic compounds.Jones, S., Martin, R., & Pilbeam, D. (1 ...
. Studies in Cambodia and Vietnam have shown their diet to consist primarily of leaves, from a wide diversity of plant species.
Studies showed they consume as many as 150 different plant species, which shows they do not have particular preferences in plants, they consume whichever is available. Fruits, flowers, and seeds were reported as the remaining portion of their diet at various proportions, according to food availability. Indeed, studies found that their diet changed from
dry season
The dry season is a yearly period of low rainfall, especially in the tropics. The weather in the tropics is dominated by the tropical rain belt, which moves from the northern to the southern tropics and back over the course of the year. The te ...
to
wet season
The wet season (sometimes called the Rainy season) is the time of year when most of a region's average annual rainfall occurs. It is the time of year where the majority of a country's or region's annual precipitation occurs. Generally, the sea ...
. During the dry season, the consumption of leaves increased, with a smaller amounts of other food consumed like flowers and fruits.
During wet season, the consumption of leaves had higher diversity of plant species and the consumption of fruits and flowers was higher.
This can be explained by Studies showed that variation of food intake also varied throughout the day. Leaves are consumed consistently throughout the day, but fruits are consumed more before midday, a habit common in folivorous non-human primate species for a more efficient energy intake needed in the morning.
Conservation
In 2000, the black-shanked douc was assessed as
Endangered
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...
by the
IUCN Red List of Threatened Species
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...
Endangered
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...
due to the rate of its population decline.
In 2015, its status was updated as
Critically Endangered due to a more alarming rapid rate of population decline.
[The main drivers of the population decline for black-shanked doucs has been habitat loss and fragmentation.] Other factors such as poaching and wildlife trade have been added as threatening factors for the conservation of this specie but they are not as detrimental as habitat loss.
Habitat loss and habitat fragmentation in Vietnam has been intensive during the 20th century due to deforestation. Following the Vietnam War
The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
, an increase in agricultural demands caused further deforestation. Increasing demands from the timber industry and mining industry also spurred deforestation. In addition, urbanization of areas in Vietnam have caused great habitat loss and fragmentation to convert forests into urban areas. Illegal conversion of protected areas into agricultural land like banana farms is still occurring in Vietnam.
Poaching, hunting and wildlife trade is the biggest threat to primates in Vietnam, as they are hunted and sold they can servea as food, medecine and pets. Even though those practices are illegal, they are still an issue in Vietnam and Cambodia. Conservation efforts have been made by establishing gun control laws, and prohibition of threatened species hunting and trade laws in Vietnam.
Climate change has also raised concern about the conservation of the black-shanked douc as endemic species tend to be more at risk of extinction due to climate change. Indeed, it has been modelled that black-shanked douc would be a vulnerable species with an increase of global average temperatures during the 21rst Century. Its spatial distribution currently does not cover a wide area and the species harbours a habitat that is currently getting more depleted. Therefore, habitat modelling of climate change has shown it will be difficult for blakc-shanked douc to find habitat suitable for their survival.
References
black-shanked douc
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 Southern Vietnam. The region they are mostly found in is called the Annamite Range, ...
Mammals of Cambodia
Mammals of Vietnam
black-shanked douc
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 Southern Vietnam. The region they are mostly found in is called the Annamite Range, ...
Taxa named by Alphonse Milne-Edwards
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