White-headed langur (Trachypithecus poliocephalus)

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Cat Ba hooded black langur pair on rock, one holding infant
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White-headed langur fact file

White-headed langur description

KingdomAnimalia
PhylumChordata
ClassMammalia
OrderPrimates
FamilyCercopithecidae
GenusTrachypithecus (1)

This beautiful and extremely rare colobine monkey is part of the genus Trachypithecus, in which the dark chocolate brown coat of adults contrasts spectacularly with the golden orange fur of infants, which turns to whitish-grey in juveniles (2) (3). The head and neck of adults are golden to yellowish-white in T. p. poliocephalus, with the pointed crest of hair on the top of the head being the most brightly coloured (3), and creamy-white in T. p. leucocephalus. A grey V-shaped area runs from the thighs to the back (3), and the fur of the pubic region ranges from white to pale orange (4). Adults are also adorned with a cape-like area of longer fur across the shoulders (3). The hands and feet are very slim, and the thumbs are notably shorter than in other primates (4).

Synonyms
Trachypithecus francoisi poliocephalus.
Size
Male head-and-body length: 55 – 62 cm (2)
Female head-and-body length: 47 – 55 cm (2)
Male tail length: 82 – 89 cm (2)
Female tail length: 77 – 82 cm (2)
Male weight: 8 – 9.5 kg (2)
Female weight: 6.7 – 8 kg (2)
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White-headed langur biology

The Old World monkeys (family Cercopithecidae) are split into two subfamilies: the Cercopithecinae and the Colobinae, or colobine monkeys. As a colobine, the white-headed langur has large salivary glands and a complex sacculated stomach. This is an adaptation to the highly folivorous lifestyle of the leaf monkey or langur. Leaves are very difficult to process, requiring digestion by bacteria in the neutral upper chamber of the stomach before moving into the lower acid region. As well as consuming a large volume of leaves daily, the white-headed langur also eats fresh shoots, flowers, bark and some fruits. The very high concentration of fibre and tannic acids in this diet would be poisonous to many other species, including humans (3).

The white-headed langur lives in groups of about five to nine individuals (2), usually with just one dominant male (3). The group sleeps together in limestone caves, spending one or two nights in each one before moving on to another. There may be up to 12 resting caves in the range of a group, although rock ledges and tall trees are also used as sleeping sites, particularly in good weather. The group leaves the sleeping sites between 5 and 6:30 am according to season, and will spend a short time socialising before moving out to forage. Resting periodically through the day, the group makes its way towards the new sleeping sites as it feeds, settling down at around 5 or 6pm (3).

Females, who all mate with the only male of the group, give birth to a single, golden-orange infant. The majority of births appear to occur in April, but very little is known of the reproductive biology of this species. The young are thought to stay with their mother’s group for up to two years, before leaving to find or start a group of their own (4).

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White-headed langur range

The Cat Ba langur (T. p. policephalus) is endemic to Cat Ba Island, the largest of more than 3,000 islands in Halong Bay off the northeastern coast of Vietnam (4). There is no evidence that this subspecies has ever lived on the mainland (3). The white-headed black langur (T. p. leucocephalus) is found in south China where it occupies seven karst regions in Guangxi Province. These regions are spread across three isolated, protected areas known as the Fusui Rare and Precious Animal Reserve, the Chongzuo Rare and Precious Animal Reserve, and the Longgang National Nature Reserve (5).

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White-headed langur habitat

In common with many members of the Trachypithecus genus, the white-headed langur is associated with the striking lush green hill forests on a limestone base that have become an icon of the southeast Asian landscape. They prefer altitudes of between 70 and 100 metres above sea level (4) and will regularly sleep within the complex cave systems of the karst landscape, particularly to shelter from poor weather (3).

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White-headed langur status

The white-headed langur is classified as Critically Endangered (CR) on the IUCN Red List. There are two subspecies. The Cat Ba langur, (T. p. poliocephalus) is classified as Critically Endangered (CR) and is less commonly referred to as the Cat Ba hooded black langur, golden-headed langur, golden-headed hooded langur or Tonkin hooded black langur. The white-headed black langur or white-headed hooded langur (T. p. leucocephalus) is also classified as Critically Endangered (CR) on the IUCN Red List (1).

IUCN Red List species status – Critically Endangered

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White-headed langur threats

Granted the dubious honour of being one of the International Primatological Society’s ‘World’s Top 25 Most Endangered Primates’, the white-headed langur is in the company of such conservation priorities as the Sumatran orangutan (Pongo abelii) and the eastern gorilla (Gorilla beringei) (6). The focus of conservation efforts must fall primarily on the Cat Ba Island subspecies, with possibly as few as 59 individuals remaining today. This shockingly low number is the result of a massive 98% decline over the course of 40 years, from between 2,500 and 2,800 individuals in the 1960s to just 53 in 2000. Such a dangerously small population of Cat Ba langurs gives the impression that the Chinese subspecies, Trachypithecus poliocephalus leucocephalus, is thriving, with between 600 and 800 individuals alive today. This is, of course, far from the truth, particularly as declines were recorded in the populations at Longgang National Nature Reserve and the Fusui Rare and Precious Animal Reserve in 1998 (5).

In both range states of this monkey species, the major threat is hunting, which is exacerbated by habitat destruction and exploitation; for the creation of sugarcane plantations in China (5), and for timber, fuel-wood, honey, bamboo shoots, edible roots, and frogs and geckos in Vietnam (7). Cat Ba Island has seen considerable change in the past 20 – 30 years. Prior to 1979 very few people lived on the island, but it is now home to a large population, of whom 12,300 live in the buffer zone of Cat Ba National Park, and 850 in the park itself. Until 1989 commercial logging took place but this is no longer viable due to the scarcity of large trees (7).

Hunting of this rare primate is not for food, as the meat is said to be smelly and fetid, but for the creation of ‘monkey balm’, a traditional ‘medicinal’ preparation. Currently the Cat Ba langurs are split into just a few isolated sub-populations, many of which are all-female groups. This fragmentation creates further challenges for the recovery of the population due to low reproductive rates and the dangers of inbreeding (3).

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White-headed langur conservation

With just 53 Cat Ba langurs in the wild and two in captivity at the Endangered Primate Rescue Centre of Cuc Phuong National Park, the Cat Ba Langur Conservation Project was started in 2000 by Műnster Zoo and the Zoological Society for the Conservation of Species and Populations (ZGAP). Given the cause of the langur’s decline, the main aim of the project was to halt poaching, with the additional intention of promoting conservation awareness amongst the inhabitants of Cat Ba Island. The project has been extremely successful in dramatically reducing deaths as a result of poaching, bringing the number from 30 deaths in the eight months prior to its start, to three deaths in the first four years of the project. In this time nine langurs were born and have survived. The langurs are closely monitored and protection measures are in place, particularly in the newly created langur sanctuary within the National Park. This highly protected area is home to 20 individuals from a large, reproducing group, which are protected by a rotation of 20 rangers – an incredible ratio of one ranger to one langur. The sanctuary is visibly marked around its circumference and is inaccessible to tourists. The Cat Ba Langur Conservation Project has constructed two new ranger stations, provided boats to ease patrols and has even seen the voluntary relocation of several local, floating households to support the rangers (3). The Cat Ba langur also has the support of Flora and Fauna International’s Flagship Species Fund (5) and the Cat Hai District Women’s Union, who implemented a project entitled ‘Contributing to Biodiversity Conservation in Cat Ba National Park through Community Activity’ (7).

Following the finding of a decline in the white-headed black langur in China, efforts were made to conserve this subspecies. With funding from the Asian Development Bank, a survey in January 2003 showed evidence of some recovery in the Fusui populations (5), and numbers in Chongzuo have seen a rise from less than 100 to more than 200 individuals since Professor Pan Wenshi of Peking University began a research program in 1996 that concentrated on the subspecies (5). Tourism has become central to economy of both Vietnam and China, and now must be controlled to prevent the disturbance of recovering habitats and species in the Conservation International’s Indo-Burmese Biodiversity Hotspot (7).

View information on this species at the UNEP World Conservation Monitoring Centre.
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Find out more

For further information on this species and its conservation see:

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Authentication

Authenticated (22/05/2006) by Matt Richardson, independent primatologist and writer.

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Glossary

Folivorous
Leaf eating.
Inbreeding depression
The decreased vigour in terms of growth, survival or fertility that follows one or more generations of interbreeding between closely related individuals.
Karst formation
An area of irregular limestone in which erosion has produced sinkholes, underground streams, and caverns.
Sacculated
Formed with or having sac-like expansions
Subspecies
A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
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References

  1. IUCN Red List (September, 2008)
    http://www.iucnredlist.org
  2. Richardson, M. (2006) Pers. comm.
  3. Cat Ba Langur Conservation Project (April, 2006)
    http://www.catbalangur.org
  4. The Primata (April, 2006)
    http://www.theprimata.com/trachypithecus_poliocephalus.html
  5. Mittermeier, R.A., Valladares-Pádua, C., Rylands, A.B., Eudey, A.A., Butynski, T.M., Ganzhorn, J.U., Kormos, R., Aguiar, J.M. and Walker, S. (2005) Primates in Peril: The World’s 25 Most Endangered Primates 2004–2006. IUCN/SSC Primate Specialist Group (PSG), International Primatological Society (IPS), and Conservation International (CI), Arlington, VA. Available at:
    http://www.gibboncenter.org/images/PDF/Top%2025%20Endangered%20Primates%20-%20Final%20Report.pdf
  6. International Primatological Society (April, 2006)
    http://www.ips2004.unito.it/index.html
  7. BirdLife Indochina – Cat Ba National Park (April, 2006)
    http://birdlifeindochina.org/source_book/pdf/3%20Red%20River%20Delta/Cat%20Ba.pdf
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Image credit

Cat Ba hooded black langur pair on rock, one holding infant  
Cat Ba hooded black langur pair on rock, one holding infant

© Terry Whittaker

Terry Whittaker
Tel: +44 (0) 1303 258322
terry.whittaker@btopenworld.com
http://www.terrywhittaker.com

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