Primates
Distinguishing Characteristics:
The coat is dense with slightly coarse hairs. Adults have a head and shoulders that are yellowish-white. The rump is pale gray. The head has a crest with pale yellow hair at the base, the tips of which are slightly gray.
The tail is long, slender, densely haired, and black. Newborns have pale yellow fur.
Biology and Ecology:
The White-headed Langur ( Trachypithecus poliocephalus) inhabits forests on rocky mountains, similar to the White-cheeked Langur. Groups range in size from 5 to 15 individuals, with an average of 9.36 individuals, and a male-to-female ratio between 1:1.5 and 1:2 (Nguyễn Phiên Ngung, 1997). Nadler, T and Hà Thăng Long, 2000 reported that the average group size of the White-headed Langur varies from 5.6 to 6.7 individuals. White-headed Langurs sleep on cliffs during the hot season and in caves during the cold season. They often choose vertical cliffs with many small caves for sleeping. They forage twice a day, in the morning and afternoon. Foraging intensity is highest in the early morning and decreases between 9 and 10 AM. They rest during midday. They are quiet in their movements, moving gently both in trees and on the ground. Their diet consists of leaves and fruits from forest trees; they do not eat animals. Preliminary observations have recorded the White-headed Langur consuming 74 plant species from 31 families, of which 54 species are consumed for young shoots, and 34 species are consumed for their fruits. They have not been observed eating any tubers. There are no studies on the reproduction of the White-headed Langur. Observations of White-headed Langur groups over many years on Cát Bà Island show that they can reproduce year-round, but the peak period is from April to October. Each litter consists of one offspring. Newborns are yellow.
Distribution:
- Within Vietnam: Hải Phòng (Cát Bà National Park).
- Global: Endemic to Vietnam.
Value:
The White-headed Langur is a valuable endemic gene source. Local people hunt the langurs for meat and use their bones to make traditional medicine.
Status:
The current population of the White-headed Langur is estimated to be around 104 – 135 individuals (Nadler and Hà Thăng Long, 2000). Due to the small population size, limited distribution, and continued hunting pressure, this subspecies is facing the risk of extinction.
Classification:
CR A1c,d C1+2b. (Critically Endangered)
Conservation Measures:
At the primate conference in October 1998 in Hanoi, IUCN (2000) classified this species as Critically Endangered (CR). It is listed in Appendix II of CITES. Protected under Decree 194-CT (1986) regarding regulations on prohibited forests; the Law on Forest Protection and Development (1991), and Group IB in Decree 32/2006/ND-CP. They are protected in Cát Bà National Park. Management efforts need to be strengthened through all forms and solutions.