Primates
Identifying Characteristics:
- Thick fur, jet black in color.
- White cheeks, with white fur extending beyond the ear tufts.
- Often possesses a black crest of fur on the head.
- The tail is longer than the body, and black in color.
Biology and Ecology:
The White-headed Langur ( Trachypithecus leucocephalus) primarily inhabits forests on limestone mountains, foraging within the closed-canopy forests that border its habitat. White-headed Langurs live in social groups. Historically, these groups were large, consisting of 20-30 individuals (Lê Hiền Hào, 1973), but currently, groups typically range from 5 to 15 individuals (Phạm Nhật, 2000).
White-headed Langurs are active in foraging during the morning and afternoon, with a rest period at midday. The intensity of foraging peaks in the morning, until around 10:00 AM, and again from 2:00 PM to 4:30 PM. Activity patterns vary throughout the year. In the hot season, langurs leave their sleeping sites early, return late, and spend a considerable amount of time resting during midday. During the cold season, they begin foraging later and return to their sleeping sites earlier.
White-headed Langurs consume young leaves and fruits from forest trees, and do not eat animals.
Research has identified 44 species from 22 plant families utilized as food sources by the White-headed Langur (Phạm Nhật, 2000). The most preferred plant species include those from the Moraceae (mulberry), Euphorbiaceae, and Arecaceae (palm) families. Studies show that, although the White-headed Langur consumes a wide variety of fruits, leaves and stems constitute a greater proportion of the diet compared to fruits and stems.
White-headed Langurs primarily sleep in caves. During the hot season, they may sleep on rocks or in trees near the cave entrance, while in the cold season, they sleep inside the caves. Sleeping sites are typically found in areas with steep cliffs.
Data on the White-headed Langur’s reproductive behavior is lacking. Field observations frequently encounter mothers with young infants throughout the year, but concentrated from March to July. Each birth produces a single offspring, which has yellow fur at birth.
Distribution:
- Within Vietnam: Hà Giang, Cao Bằng, Tuyên Quang, Bắc Kạn, Lạng Sơn.
- Globally: China (Guangxi).
Value:
The White-headed Langur is a valuable primate species with scientific and aesthetic value.
Status:
No studies have been conducted to assess the population size of the White-headed Langur. Lê Hiền Hào (1973) reported that the species was previously common in certain areas such as Cai Kinh (Lạng Sơn) and Ba Bể (Bắc Kạn). Recent field surveys conducted in Na Hang (Tuyên Quang), Ba Bể and Nà Rì (Bắc Kạn), Phong Quang (Hà Giang), and Hữu Liên (Lạng Sơn) indicate that the White-headed Langur is now a rare species. The primary factors contributing to the decline of the White-headed Langur population are habitat loss due to shrinking natural forests on limestone mountains, and hunting pressure.
Classification:
- EN A1c,d C2a
Conservation Measures:
- IUCN (2000) classified this species as Vulnerable (VU).
- The Primate Conference held in Hanoi in October 1998 and the Red List classified the White-headed Langur as Endangered (EN).
- Listed in CITES Appendix II.
- Protected by Decision 194-CT (1986) regarding the designation of protected forests; the Forest Protection and Development Law (1991), and Group IB in Decree 32/2006/ND-CP.
- Protected within Ba Bể National Park, Na Hang Nature Reserve, Na Rì Nature Reserve, Phong Quang Nature Reserve, and Hữu Liên Nature Reserve. These areas possess the necessary ecological conditions for the species, and in-situ conservation remains the best approach. Increased management of these national parks and nature reserves is essential.