Identifying Characteristics:
- Fur typically ranges from gray to reddish-brown, lighter on the posterior.
- Hair on the head grows backward.
- Often possess a crest.
- Face is pinkish.
- Adult males often have two tufts of white hair on either side of their mouth, resembling whiskers.
- Females have sparser hair around the mouth.
- Newborns are black.
- The tail is long and well-furred, usually reaching 3/4 or more of the body length.
Biology, Ecology:
- Attains sexual maturity at 50-51 months (Harvey, 1987).
- Gestation period: 160-170 days (Nowak, 1991).
- Interbirth interval: 13 months (12-24 months) (Ross, 1992).
- Lifespan: 37-38 years (Michael, 1993).
- Diet primarily consists of fruits (64%), seeds, tree hearts, leaves, other plant parts, and animals like insects, frogs, crabs, etc. (Payne, 1985).
- Diurnal and arboreal.
- Highly skilled swimmers and often leap into water from branches.
- The dominant male typically marks its territory less than other monkey species.
- Juveniles frequently play within the group.
- They often play with each other for about two years.
- Males tend to play with males, and females with females.
- Often sit in groups on roadsides, unafraid of passing vehicles.
- Typically live in groups, rarely found alone.
- Groups have a multi-male, multi-female structure (Roonwal, 1977), averaging 2.5 females per male.
- Group size ranges from 10-100 individuals (Wolfheim, 1983).
- Inhabit primary and secondary forests, bamboo forests, evergreen forests, sparse forests, riverbanks, coastlines, coastal mangrove forests, and along rivers up to an altitude of 2000m (Wrangham, 1993).
Distribution:
- Within Vietnam: From Thua Thien – Hue to Kien Giang provinces.
- Worldwide: Southern and Southeast Asia.
Value:
- Used as research specimens and objects for scientific study.
- With proper protection and breeding, they can become a source of animals for testing vaccines for human use.
Status:
- Prior to 1975, the species was common in forests of the southern provinces from Thua Thien – Hue to Kien Giang, estimated to cover >5,000 km².
- The species’ status has changed significantly since 1975. Population numbers have decreased sharply. Currently, there are about 30 subpopulations.
- Causes of decline: Habitat destruction, deforestation, reduction of natural forest area, and hunting for meat, traditional medicine, commercial trade, and export.
Classification:
- LR nt (Lower Risk, near threatened)
Conservation Measures:
- Included in the Vietnam Red Book 2000 and the list of protected species of the Forestry sector (Appendix IIB, Decree 32/2006/ND-CP dated April 22, 2002, by the Government).
- Effective enforcement of laws, regulations, and government decrees on wildlife protection is needed.
- Establishment of nature reserves and management programs for wildlife in general, and for threatened species in particular.
- Breeding programs for this species have been implemented in some captive breeding facilities.