Identification
The fur color is typically dark brown, but variations from black to red also occur. The underside of the abdomen is always lighter than the upper parts. The back is reddish-brown to dark brown. The face is mostly red. Hair on the crown of the head often radiates outwards. Hair on the cheeks radiates backward. Red-faced monkeys have a short, thick tail, no more than 1/3 the length of the hind foot. The penis of adult males is unusually long. A prominent feature is large, hairless ischial callosities (buttock pads).
Biology and Ecology
Gestation period: 178 days (Ross, 1992). Interbirth interval: 19 months. Lifespan: approximately 30 years (Ross, 1991). The primary diet consists of fruits, seeds, young leaves, buds, and animals including insects, birds, and eggs (Richard, 1989). They are diurnal. They are arboreal and also move on the ground. Red-faced monkeys often travel on the ground in forests and along riverbanks and streams (Richard, 1989), and have not been observed swimming. During foraging, they emit calls to communicate with each other or when sensing danger. A dominant male usually leads the group to protect the troop. Group structure: multi-male, multi-female, with group sizes varying from 5-40 individuals (Wolfheim, 1983). A group can move 400-3000 meters in a day (Betrand, 1969). Red-faced monkeys often inhabit low-lying monsoon forests, dry forests, and dense forests up to 2000 meters above sea level. However, they are also observed in residential areas, temples, and shrines (Wolfheim, 1983).
Distribution
- Within Vietnam: Widespread throughout the country: Lai Châu (Tuần Giáo, Quỳ Nhai, Kim Sơn, Mường Tè), Lào Cai (Sapa, Sình Hồ), Sơn La (Mộc Châu, sông Mã), Hà Giang, Cao Bằng (Trùng Khánh), Tuyên Quang (Tát Kẻ, Chiêm Hoá, Bản Bung), Hòa Bình (Đà Bắc, Mai Châu, Kim Bôi), Thanh Hóa (Như Xuân, Hồi Xuân), Nghệ An (Bến Thủy), Hà Tĩnh (Hương Khê, Hương Sơn), Quảng Bình (Tuyên Hóa, Minh Hóa, Bố Trạch), Thừa Thiên – Huế (Bạch Mã, Hải Vân, Huế), Quảng Trị (Dakrong, Lao Bảo), Gia Lai (Kon Hà Nừng, Kon Cha Răng), Kon Tum (Mom Ray), Đắk Lắk (Krông Nô, Đăc Min, Ea Sup, Mdrak), Lâm Đồng (Đà Lạt).
- Worldwide: South and Southeast Asia
Value
They are a subject of scientific research. Moreover, if well protected and bred, they can become a source of genetic material for vaccine testing, serving humanity.
Conservation Status
Before 1975, this species was common in forests from the northern to southern provinces of Vietnam, with an estimated total area of >30,000 km2. Since 1975, the species’ situation has changed significantly, with a sharp decline in population. The current number of subpopulations is about >50. The causes of this decline include habitat destruction, deforestation, the reduction of natural forest areas, and hunting for meat, medicinal products, and trade and export.
Classification
VU A1c,d B1+2b,c. (Vulnerable)
Conservation Measures
Included in the Vietnam Red Data Book 2000 and the list of protected species of the forestry sector (Appendix IIB Decree 32/2006/ND-CP dated April 22, 2002, of the Government). Recommendations: Effective implementation of laws, regulations, and decrees regarding wildlife protection is needed. Establishment of nature reserves and management programs for wildlife in general, and endangered species in particular.