Distinguishing Characteristics:
Adults have thick, long, soft, black fur. Their abdomens are blackish-gray. The groin and inner thighs are dirty grayish-white. They have a crest of black fur on the crown of their heads. Two small white stripes run from the corners of the mouth, across the cheeks, and above the ears to the nape of the neck. The tail is longer than the body, evenly tapered, densely furred, and black. Newborns have golden-yellow fur, which gradually turns black after four months. After one year, the fur color resembles that of adults.
Biology and Ecology:
The Hà Tĩnh Langur (Voọc Hà Tĩnh) inhabits rich forests with many large trees growing on limestone mountains. They are not found in forests on soil, even in areas very close to limestone mountains.
Like other langur species and subspecies, the Hà Tĩnh Langur lives in troops. Field observations show that the number of individuals in a troop varies from 5 to 18, with an average of 7.3 individuals per troop. The troop structure comprises 73.7% adults, 14.9% sub-adults, and 11.4% juveniles. The male/female ratio varies from 1/3 to 1/4 (one male living with three or four females). The troop is led by a single male. This male often travels alone while the troop forages. He is also the first to check sleeping sites before the troop arrives. The Hà Tĩnh Langur is diurnal, agile at climbing, and runs quickly on branches, capable of long jumps. Their territories are typically stable for at least two years (according to local people, they can live in one area for many years) if they are not hunted. Langurs sleep on steep cliffs and in small caves 25-40m above the ground. Within their territory, the Hà Tĩnh Langur has 2 or 3 sleeping sites, using each for 3-5 nights.
The Hà Tĩnh Langur’s diet consists of young leaves and fruits from forest trees. They have not been observed eating animals. Field investigations in Quảng Bình and research at the Primate Rescue Center of Cúc Phương National Park have recorded the Hà Tĩnh Langur eating 138 species belonging to 38 plant families, of which 36 species (from 20 families) are considered their preferred foods. 137 species are eaten for their leaves, 9 for their fruits, and only 1 for its bark. The average daily food intake is 879.2g for an adult individual, equivalent to 10% of their body weight. Reproduction data for the Hà Tĩnh Langur is limited. Monitoring at the Primate Rescue Center of Cúc Phương National Park and field observations show that the Hà Tĩnh Langur breeds year-round, but primarily from February to August. They give birth to one infant per litter. Newborns are bright yellow, gradually turning black after two weeks, and their fur is almost entirely black after three months.
Distribution:
- Within Vietnam: Thanh Hóa (Như Xuân), Nghệ An (Con Cuông), Hà Tĩnh (Xóm Cục), Quảng Bình (Minh Hóa). Surveys from May 1995 to September 2002 only recorded the Hà Tĩnh Langur in Tuyên Hóa, Minh Hóa, Bố Trạch, and Quảng Ninh districts, Quảng Bình province. There is no information on this subspecies in Thanh Hóa, Nghệ An, and Hà Tĩnh.
- Worldwide: Found only in Vietnam.
Value:
The Hà Tĩnh Langur is a narrow endemic primate species, rare, and valuable for research on its behavior and growth in the wild.
Status:
Distribution and population surveys conducted over four years (1995-1998) estimated a population of no more than 800 individuals, primarily concentrated in the Phong Nha – Kẻ Bàng limestone mountain region.
Classification:
EN A1c,d
Conservation Measures:
The Vietnamese Red Data Book (1992) classified this subspecies as Near Threatened (V). The Primate Conference in October 1998 in Hanoi, and IUCN (2000), classified this species as Endangered (EN). Listed in Appendix II of CITES. Protected by Decision 194-CT (1986) on regulations for prohibited forests; Forest Protection and Development Law (1991), Group IB in Decree 32/2006/ND-CP. It is protected in Phong Nha – Kẻ Bàng National Park. Management of the aforementioned national parks and nature reserves needs to be strengthened.