T. p. poliocephalus
Confined to Cat Ba Island, in Ha Long Bay off the northeastern cost of Viet Nam. There it is further restricted to about a 100 km2 area of occupancy, mostly inside Cat Ba National Park (Stenke and Chu Xuan Canh 2004). It ranges from 70-100 m in elevation (Le and Campbell 1994) and possibly from 0 to 200 m.
T. p. leucocephalus
Occurs in south China (southwestern Guangxi province), in isolated areas from the Shiwan Dushan north to the Zuo River, specifically in the karst hills of Gang Nature Reserve, Fushui Nature Reserve, Chongzuo Nature Reserve, and Longrui Nature Reserve.
Habitat and Ecology
IUCN Red List Assessment
Red List Category
Red List Criteria
- 2000Critically Endangered
As of 2003, T. p. leucocephalus totaled about 700-800 individuals remaining in the wild, 250 of which live in Nong Gang, a maximum of 350 individuals live in Nong Lin. Also as of 2003, the population had begun to grow after a period of human-induced decline (Wang and Tong 2004). A survey conducted in Fusui Rare and Precious Animal Nature Reserve between September 1996 and April 1997, found a 24% decline in the population density over the past 10 years, with a current population of less than 150 langurs (Li et al. 2003).
In China, clearing of land with fire, burning of agricultural residue and burning charcoal often leads to uncontrolled fires that escape into adjacent karst landscapes. The white-headed Langur is surrounded in some areas by subsistence agriculture, such that much of the habitat is fragmented (Li and Rogers 2005). Tree cutting for firewood has caused further degradation to the remaining habitat (Li and Rogers 2005). Along with habitat destruction, poaching has been the primary cause of the most recent decline in the population (Wang and Tong 2004). There is some evidence that breeding is hindered in degraded habitats.
Since November 2000, the subspecies T. p. poliocephalus and its habitat on Cat Ba have been the subject of the Cat Ba Langur Conservation Project (implemented by the Zoological Society for the Conservation of Species and Populations, ZSCSP), which has been focused on the improvement of protection status for the subspecies and its habitat, and has initiated two important programs. The first is a langur sanctuary located inside Cat Ba National Park and a ?buffer zone? of the World Heritage Site ?Halong Bay.? Thirty-five percent of the remaining population lives in the sanctuary. The second is a langur-guarding program that is meant to protect 35% of the population that exists outside of the national park. This program puts the subpopulations and their ranges under the control of local people that patrol the ranges and offer community conservation education. The most important steps in the recovery of this subspecies now are continued protection from poaching and encroachment, a reduction in the habitat fragmentation and subpopulation isolation, and an increase in reproductive output and genetic health of the entire population, suggesting the need for translocation (Stenke and Chu Xuan Canh 2004).
The largest populations of T. p. leucocephalus are expected to recover under proper conservation of their Nong Guan and Nong Lin limestone habitats (Wang and Tong 2004). Nong Guan and Nong Lin are now being included in a larger proposed national-level nature reserve called Chongzuo Eco-Park, a special nature reserve for the white-headed langur (381 km2) with a population of about 250 individuals (Nadler 2003). However, considering the precarious status of the populations of this subspecies, reliable information is desperately needed about the precise effects of habitat degradation on its activity and survival (Li and Rogers 2005).
There are currently no specimens of T. p. leucocephalus in captivity; a small number of T. p. poliocephalus are reported in the collection of the Endangered Primate Rescue Center, Cuc Phuong National Park, Viet Nam (Nadler 1999).
The white-headed langur (Trachypithecus poliocephalus) is a critically endangered langur from Cat Ba Island, Vietnam (T. p. poliocephalus), and Guangxi, China (T. p. leucocephalus). Both taxa are overall blackish, but the crown, cheeks and neck are yellowish in T. p. poliocephalus, while they, as suggested by its scientific name, are white in T. p. leucocephalus. As all members of the Trachypithecus francoisi species group, this social, diurnal lutung is found in limestone forests.
The nominate subspecies, often known as the golden-headed or Cat Ba langur, is among the rarest primates in the world, and possibly the rarest primate in Asia. The taxonomic position of the Chinese population, while also highly endangered, is more confusing. It has been considered a partially albinistic population of the Francois' langur (T. francoisi), a subspecies of Francois' langur, a valid species (T. leucocephalus), or a subspecies, T. poliocephalus leucocephalus. Comparably, poliocephalus was considered a subspecies of Francois' langur until 1995.
According to the Cat Ba Langur Conservation Project, the The Cat Ba langur's skin is black and the pelage color is dark brown; head and shoulder are bright golden to yellowish-white. The tail is very long (ca. 85 cm) compared to the body size (ca. 50 cm). Babies are colored golden-orange; the pelage starts to change its color from about the fourth month on. Males and females look alike. The Cat Ba langurs live in groups, usually one male with several females and their offspring. They are diurnal animals, adapted to living in limestone habitat. Each group has its own territory, defended by the adult male who also initiates the location of the group. The females usually give birth to a single baby every 2–3 years, which becomes mature at 4–6 years old. Langurs have an average life expectancy of 25 years. Food mainly consists of leaves, but also fresh shoots, flowers, bark, and some fruits.
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