Dollman’s snub-nosed langur, Dollman’s snub-nosed monkey, Tonkin snub-nosed langur, Dollman's snub-nosed monkey
The Tonkin snub-nosed monkey or Dollman's snub-nosed monkey (Rhinopithecus avunculus ) is a slender-bodied arboreal Old World monkey, endemic to northern Vietnam. It has black and white fur, a pink nose and lips, and blue patches around the eyes. It is found at elevations from 200 to 1,200 m (700 to 3,900 ft) on fragmentary patches of forest on craggy limestone areas. First described in 1912, the monkey was rediscovered in 1990 but is exceedingly rare. In 2008, fewer than 250 individuals were thought to exist, and the species was the subject of intense conservation effort. The main threats faced by these monkeys are habitat loss and hunting, and the International Union for Conservation of Nature has rated the species as "critically endangered".
The Tonkin snub-nosed monkeys are easily recognizable primates, exhibiting a rather unusual appearance. Their eyes are surrounded by faint, blue colored stripes. The ears are tufted, while the nose is flat and turned upward. They have a wide and flattened face with thick, pink lips. There is no information on life expectancy of this species. However, other colobine monkeys are known to live around 29 years in captivity and 20 years in the wild. The Tonkin snub-nosed monkeys are the largest primates, found in Vietnam. Meanwhile, this species is presently among the most endangered primates around the globe, which was thought to have gone extinct until 1989, when it was found again.
Tonkin snub-nosed monkeys are native to Vietnam, occupying the northern parts of the country. The original range of this species covered the area east of the Red River. During the last decades, these animals have lost a significant part of their range. Currently, they are found in tiny, scattered areas in the provinces of Tuyen Quang, Bac Kan, Ha Giang and Thai Nguyen. Tonkin snub-nosed monkeys are most commonly found in primary forests. Overall, these primates prefer subtropical evergreen forests with karst limestone hills and mountains.
Tonkin snub-nosed monkeys display strong social habits, forming groups that consists of a single adult male and numerous females with their young, which socialize, feed, sleep, and travel together. These groups occasionally divide into smaller sub-groups as well as unite to in bigger super-groups. Additionally, males are known to gather into all-male units. Tonkin snub-nosed monkeys are diurnal creatures, sleeping at night and being active by day. They sleep on lower tree branches near mountain slopes, which serve as barriers against cold winds. Their habit of splitting into smaller groups and mixing with other groups suggests that these animals are non-territorial. When travelling among trees, they walk, leap and climb, using all of their four legs. Adult individuals of this species spend their time hung from tree branches, leaping from tree to tree as well as arm swinging.
Tonkin snub-nosed monkeys are herbivores (folivores and frugivores), they generally consume leaves, fruits, flowers and seeds.
Tonkin snub-nosed monkeys are polygynous, which means that one male mates with multiple females. The mating behavior and habits of this species is insufficiently explored due to small overall population and lack of observations in the wild. However, gestation period is known to last for 200 days, yielding 1 - 2 infants. Females produce young during the spring and summer months. Duration of nursing period is unknown. The age of reproductive maturity is 7 years old in males and 4 years old in females.
This species has lost a significant part of its original range due to large-scale deforestation and continuous hunting. As a result, Tonkin snub-nosed monkeys are now found only in 5 isolated populations. Currently, these monkeys still suffer from destruction, degradation and fragmentation of their habitat. Throughout their range, they face massive deforestation for agricultural land, development, road construction, both legal and illegal tree felling, gold mining as well as production, using non-timber materials. Nevertheless, the primary threat to the population of this critically endangered species is hunting, although its meat is known to be bad-testing. However, this monkey is often killed when seen in the wild, being used in food and traditional medicine.
According to the IUCN Red List, the total population of Tonkin snub-nosed monkeys’ is approximately 250 animals, inhabiting their known range (the total range of this species is thought to be unknown). Overall, the species’ numbers are decreasing today, and the animal is classified as Critically Endangered (CR) on the IUCN Red List.
These primates are known to maintain herbivorous diet, thus controlling plant communities of the local ecosystem. In addition, this diet allows them to act as important seed dispersers of the plants they use.
