Identification:
The coat color ranges from ashy gray to dark brown, with a crest of fur on the head. The skin around the eyes is bluish-white. The fur on the back is darker than on the abdomen. The flanks have long hairs with silver-tipped ends. The tail is longer than the body, with very long tail hairs. The limbs are black, with the upper arms, legs, and tail having a silvery-gray hue.
Biology and Ecology:
The primary diet consists of fruits (24.4%), leaves (58.4%), and other food sources (9.7%). Gray langurs breed year-round. Pregnant females have been observed in March and July. Mothers carrying infants have been observed in April, June, October, and December.
They typically give birth to one offspring per litter, which is light yellow in color. Gray langurs primarily inhabit high-elevation forests on limestone mountains and do not reside in mixed bamboo forests. They are diurnal, spending their lives in the trees. They can be found foraging in the shrubby areas near forests. They usually sleep on steep limestone cliffs or on tree roots growing on precarious cliffs. In winter, they sleep in caves or in dense, wind-protected tree canopies. Gray langurs coexist with rhesus macaques and golden monkeys, but do not compete for food resources. Their natural predators include large carnivorous mammals. They live in groups ranging from 3 to 30 individuals.
Distribution:
- In Vietnam: Lai Châu (Mường Nhé, Mường Tè), Hà Tây, Hòa Bình (Kim Bôi), Thanh Hóa (Hồi Xuân, Thường Xuân), Ninh Bình (Cúc Phương), Nghệ An (Nghĩa Đàn, Quế Phong, Kỳ Sơn), Hà Tĩnh (Anh Sơn), Quảng Bình (Bố Trạch, Tuyên Hóa, Minh Hóa).
- Worldwide: Myanmar, Southern China, Thailand, Laos, Cambodia.
Use Value:
This species has high scientific value and can be used as a research specimen. It can also be kept as a decorative animal in zoos or wildlife parks.
Conservation Status:
Before 1975, this species was commonly found in old-growth forests in the Northwest provinces of Vietnam, covering an estimated area of >2,000 km².
Since 1975, the species’ status has changed dramatically. The population size has decreased significantly. The number of current subpopulations is >10. The causes of this decline may include: habitat encroachment, deforestation, the shrinking area of natural forests, and the species being hunted for traditional medicine, trade, and export.
Classification:
VU A1c,d (Vulnerable)
Conservation Measures:
Included in the Vietnam Red Book 2000 and the list of protected species of the Forestry sector (Appendix IB, Decree 32/2006/ND-CP dated April 22, 2002, of the Government).
Recommendations:
Effective implementation of laws, regulations, and government decrees related to wildlife protection is needed. The establishment of nature reserves and management programs for wildlife in general, and threatened species in particular, are essential. The species is currently protected in conservation areas such as: Mường Nhé Nature Reserve (Lai Châu), Vũ Quang, Kẻ Gỗ (Hà Tĩnh), and Khe Nét (Quảng Bình).