TONKIN SNUB-NOSED MONKEYS: CHARACTERISTICS, BEHAVIOR, HUMANS

TONKIN SNUB-NOSED MONKEYS

Tonkin snub-nosed monkeys

Tonkin snub-nosed monkeys (Rhinopithecus avunculus) are a small gray, white and black primate that and live in Northern Vietnam. Vietnam’s largest primate species, they have a very distinctive look that is almost comical due to the upturned nose, tufted ears, pale blue rimmed eyes and thick, pink lips. They are 51–65 centimeters (20–26 inches) long, with a 66–92 centimeter (26–36 inch) tail. They live in forests and eat leaves, fruit, flowers, and seeds. They are critically endangered. There are only around 250 of them. Populations have been confirmed in the past in seven provinces of Northern Vietnam: Ha Giang, Tuyen Quang, Cao Bang, Yen Bai, Bac Kan, Thai Nguyen, and Quang Ninh. They have been found fairly recently in Ha Giang, Tuyen Quang, and Bac Kan Provinces, and possibly in Thai Nguyen Province. Their population is declining. [Sources: Wikipedia; Rachel Cherka, Animal Diversity Web (ADW)]

The Tonkin snub-nosed monkey is also known as the Tonkin snub-nosed langur and Dollman's Snub-nosed monkey. They are found only in subtropical broad-leaf and bamboo forests that have monsoon rainfall and tropical temperatures. These forests are usually found on top of limestone hills at elevations of less than 1000 meters (3280.84 feet). Tonkin snub-nosed monkeys are the only snub-nosed monkeys that occur in subtropical areas. Lifespans of Tonkin snub-nosed monkeys are not reported.

Tonkin snub-nosed monkeys are one of the 25 most endangered species of primate in the world. They are only found in Vietnam and was believed extinct until they were rediscovered in 1989. Little is known about them as they're very rare, elusive and live in remote areas. In May 2002, Fauna & Flora International (FFI) discovered a vitally important population in a small patch of limestone forest known as Khau Ca, in Ha Giang Province. [Source: Fauna and Flora International]

Tonkin Snub-Nosed Monkey Characteristics

Tonkin Snub-nosed monkeys range in weight from 8.3 to 13.8 kilograms (18.28 to 30.40 pounds) and range in length from 51 to 65 centimeters (20.08 to 25.59 inches). The head and body length is 40 to 55 centimeters (15.7 to 21.6 inches). The tail is 65 to 92 centimeters (25.6 to 36.2 inches).. Sexual Dimorphism (differences between males and females) is present: Males are larger than females. Sexes are colored and patterned differently. Males on average weigh approximately 14 kilograms; females: 8.5 kilograms. Males have more pronounced orange coloration around the throat and are darker black around the mouth. [Source:Earth’s Endangered Species ^^ Rachel Cherka, Animal Diversity Web (ADW) /=]

range of the Tonkin snub-nosed monkeys

According to Earth’s Endangered Species: Tonkin Snub-nosed monkeys have a slender body with a creamy white front (Stomach, inside of upper arms and legs and face) and a black-dark grey back, shoulders, backs of arms and legs and backs of feet and hands. They have a bald, flat face with dark eyes surrounded by light blue and thick, vibrant pink lips surrounded by dark blue or gray as well as small tufted ears. Their nose is "smushed" and upturned showing the nostrils, which is where they get the name "snub-nosed monkey" and on the neck, adults they have orange throat patches. They also have a very long tail that isn't prehensile and is grey at the base, becoming more white near the tip. While males and females can't easily be distinguished, infants can. Instead of black fur, they have grey and they also lack orange throat patches and white-tipped hairs on the tail. ^^

According to Animal Diversity Web: Both sexes of adult Tonkin snub-nosed monkeys have upturned noses and slender digits on the hands and feet in comparison to other species in the genus Rhinopithecus. Coat color and pattern variation has been reported among populations and individuals. They have orange coloration on the throat and dark coloration that outlines the mouth. In juveniles, the black parts of the fur appear gray, they lack the orange in the throat region, and the black around the mouth is not as pronounced as it is in adults. Dental formula in the genus Rhinopithecus is I 2/2, C 1/1, P 2/2, meters 3/3, for a total of 32 teeth. There is sexual Dimorphism in terms of canine size, with males having larger canines on both top and bottom jaw. /=\

Tonkin Snub-Nosed Monkey Feeding and Predators

Tonkin snub-nosed monkeys are primarily herbivores (primarily eat plants or plants parts), folivores (eat leaves) and frugivores (eat fruits). Among the plant foods they eat are leaves, wood, bark, or stems seeds, grains, and nuts fruit flowers. [Source: Rachel Cherka, Animal Diversity Web (ADW) /=]

Tonkin snub-nosed monkeys primarily eat leaves from trees, mainly bamboo or other evergreen trees but also eat a variety of other plant parts and fruits as well. The diet is comprised of 28 percent leaf stems, 28 percent fruits, 11 percent young leaves, 22 percent unripe fruit, eight percent flowers, and three percent seeds. Thirty-one food species have been identified belonging to 21 families have been recorded in the Tonkin sub-nosed monkey diet. The plant species Iodes seguini, Garcinia fagraeoides, Acer tonkinensis, Excentrodendron tonkinensis, and Brassaiopsis stellate are consumed the most.

Tonkin snub-nosed monkeys have a specialized digestive system that is adapted for the digestion of leaves, including a sacculated stomach. Their strong jaw musculature is related to their dietary preferences for tough plant foods. It is unclear what role these animals play in the ecosystem as they are rare but they probably help the ecosystem by dispersing seeds. /=\

Humans have been known to hunt and eat Tonkin snub-nosed monkeys despite reports that their meat tastes bad. No other predators of Tonkin snub-nosed monkeys are known, but it is asummed adults might be taken by forest cats such as clouded leopards and young are preyed on by arboreal trees), snakes and large birds of prey.

Tonkin Snub-Nosed Monkey Behavior and Communication

Tonkin snub-nosed monkeys are arboreal (live mainly in trees), scansorial (able to or good at climbing), diurnal (active mainly during the daytime), motile (move around as opposed to being stationary), sedentary (remain in the same area), and social (associates with others of its species; forms social groups). Home range size has not reported. Some observations suggest that they spend most of their time within a range of roughly 10 square kilometers. [Source: Rachel Cherka, Animal Diversity Web (ADW) /=]

Tonkin snub-nosed monkeys hangs out in bands of 25 to 80 individuals organized around family groups that forage and rest together. They move through the trees searching for edible leaves, fruits and seeds. When threatened large groups break up into smaller bands. They move along the branches of the canopy on all fours, leaping to other branches when necessary and occasionally hanging from the branches and swinging from tree limb to tree limb using their arms. [Source: Earth’s Endangered Species]

According to Animal Diversity Web: Tonkin snub-nosed monkeys typically organize themselves into either all male groups or groups of a single male with multiple females and juveniles; these groups typically feed, sleep, and travel together. The sleeping sites for this species are usually on lower branches of trees near steep mountain sides so as to be protected from cold winds at night. Their fission-fusion way of forming large groups and breaking up into smaller groups suggests that there is inter-group tolerance. Because they do this the species does not appear to be territorial. Females allogroom other members of the group.

Tonkin snub-nosed monkeys sense and communicate with vision, touch, sound and chemicals usually detected by smelling. They have different calls including a loud hiccough-like sound that (“huu chhhk”) and is used either in alarm calls or to communicate with other individuals. This kind of communication usually occurs during traveling or when locating a resource. Alarm calls are usually done in the presence of researchers. There has been no research on communication and perception in Tonkin snub-nosed monkeys.

Tonkin Snub-Nosed Monkey Mating, Reproduction and Offspring

Tonkin snub-nosed monkeys are polygynous (males have more than one female as a mate at one time). The breeding season in Tonkin snub-nosed monkeys has not reported. The number of offspring ranges from one to two. There has been little research on the reproductive behavior of these monkeys as they are rare and difficult to observe.[Source: Rachel Cherka, Animal Diversity Web (ADW) /=]

According to Animal Diversity Web: A female will engage the male by getting him to follow her to various branches; she will then move her tail above and to one side of her body prior to male mounting. Once the male has positioned his feet on the branch he will mount the female from the rear initiating copulation which was reported to have lasted approximately 43 seconds. In one case, after copulation the female moved to a neighboring tree and the male moved to a lower branch where he moved his forelimb in front to of his face and briefly shook his head. This description is the only observed mating event in Tonkin snub-nosed monkeys. /=\

The average gestation period is 200 days. On average females reach sexual or reproductive maturity at age four years and males do so at age seven years. Females usually give birth in the spring or summer. Nothing has been reported about the lactation period of this species. Not much known about the level of parental care exhibited. Adult females allogroom other members of the group.

Tonkin Snub-Nosed Monkeys and Humans

Tonkin snub-nosed monkeys have been hunted by locals for food source and as a source of traditional "medicines," which have no true medicinal value. It is reported that body parts are sometimes traded the borders of Vietnam and China. The hunting of this species for these purposes poses one of the biggest threats to its conservation and has therefore been made illegal. [Source: Rachel Cherka, Animal Diversity Web (ADW) /=]

Tonkin Snub-nosed monkeys have been consumed by humans even though it has been said their meat tastes bad. Their forest habitat has been heavily deforested and fragmented due to agriculture, human settlements, legal and illegal logging, mining (mainly for gold) and the harvest and collection of non-timber products. Even in protected areas, their habitat is illegally destroyed.[Source: Earth’s Endangered Species]

Khau Ca forest protection area in northern Vietnam near the China border is home to some of the largest groups of Tonkin snub-nosed monkeys. People who live in near the forests where these monkeys live harvest bamboo and cut down trees.

Tonkin Snub-Nosed Monkey Conservation

Tonkin snub-nosed monkeys have been recognized as one of the world’s 25 most Endangered primates since 2000 and were ranked as number eight in the 2006 to 2008 report. On the International Union for Conservation of Nature (IUCN) Red List Tonkin snub-nosed monkeys are listed as Critically Endangered. On the US Federal List they are classified as Endangered. In CITES (Convention on International Trade in Endangered Species of Wild) they are in Appendix I, which lists species that are the most endangered among CITES-listed animals and plants.

Currently, their population is believed to number around 250 individuals. It could be larger as there could be some living in remote areas. According to one conservationist a population of 200 is necessary for the species to survive. A survey in 2006 estimated the total population for the entire species was about 150 individuals, but since then groups of monkeys thate were previously unknown have been discovered but at the same time poach and loss of habitat and deforestation may have lowered their numbers.

The main long-term threat to the Tonkin snub-nosed monkey at Khau Ca forest protection area is the limited area of the forest. Surveys have highlighted several potential threats to the species and its habitat locally, including illegal logging, hunting, exploitation of a range of non-timber forest products, shifting cultivation, fuelwood collection and grazing of livestock in the forest.Fauna & Flora International’s Vietnam Conservation Support Programme and Ha Giang Provincial Forest Protection Department are implementing a community-based primate conservation project with the aim of providing long-term conservation for the Tonkin snub-nosed monkey in Ha Giang Province. [Source: Fauna & Flora International (FFI)]

The Tonkin snub-nosed monkey is protected by law and occur in some protected areas and national parks. International trade of them and their parts is prohibited due to their listing on CITES and helpful efforts are being carried out by Fauna and Flora International, and they have helped discover a new population near the northern border of China and Vietnam. In addition, there is a conservation action plan currently working to save Tonkin Snub-nosed Monkeys by further researching, raising awareness, enforcing stricter laws and more. Although these efforts have tried and are trying to conserve these rare primates, their threats still severely endanger them and perch them right near the brink of extinction. [Source: Earth’s Endangered Species]

Image Sources: Wikimedia Commons

Text Sources: Animal Diversity Web animaldiversity.org ; National Geographic, Live Science, Natural History magazine, David Attenborough books, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The New Yorker, Time, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.

Last updated December 2024