YUNNAN SNUB-NOSED MONKEY

Pygathrix (or Rhinopithecus) bieti (or roxellana bieti)

Physical Description

The Yunnan Snub-nosed Monkey is an extremely rare primate found only in Tibet and China. Alternative names for the Monkey include the Snow Monkey, Biet’s Snub-nosed Monkey, the Black Snub-nosed Monkey, the Black Snub-nosed Langur, and the Yellow-haired Dechen Monkey. The Yunnan Snub-nosed Monkey lives at higher altitudes than any other non-human primate. The French scientist Milne-Edwards first identified the Yunnan Snub-nosed Monkey in 1897.

No reliable reports of sightings of the animal surfaced for several decades afterwards, leading some to suspect that the Yunnan Snub-nosed Monkey had become extinct.

In 1962, however, a member of the Chinese Animal Research Team obtained approximately eight incomplete Yunnan Snub-nosed Monkey pelts in the Dechen area of Yunnan in Southeast Tibet.

Then, in November 1979, a Chinese scientist from the Kunming Institute of Zoology killed a Yunnan Snub-nosed monkey, finally providing conclusive evidence that the Monkey did still indeed exist.

The Yunnan Snub-nosed Monkey has large pink lips and a distinctive upturned nose that lacks nasal bones. The Monkey has long fur that is mainly dark brown to black in colour.

In adult monkeys, or those over eight years of age, the back, ends of the arms and legs, end of the tail, and top of the head are dark brown to black, while the armpits, chest, belly, rump, flanks, and tips of the ears are white to yellowish gray.

Adults have light pink skin around their muzzle and pale yellowish or greenish skin around their eyes. Newborns, on the other hand, have an entirely white coat, a blue face, and pink toes and fingertips. The young monkeys’ fur darkens gradually with age. Male Yunnan Snub-nosed monkeys have longer hair on their flanks, backs, and the top of their heads than do the females.

The Yunnan Snub-nosed Monkey’s tail is equal in length, or slightly longer, than the Monkey’s body. The Yunnan Snub-nosed Monkey’s body length ranges from 51 to 83 centimetres (20 to 33 inches). The average weight of males is 15.3 kilograms (33.7 pounds), while females weigh on average 9.1 kilograms (20 pounds).

Habitat

The Yunnan Snub-nosed Monkey lives in evergreen coniferous forests composed mainly of fir, spruce, evergreen oak, and rhododendron species, at elevations from 3,000 to 4,500 metres (9,800 to 14,800 feet). In forests at these heights, temperatures average below zero degrees Celsius for several months of the year, frost is present on the ground for about 280 days per year, and snow can accumulate to over one meter (3.3 feet) in depth.

Recent surveys suggest that there are currently about 13 isolated sub-populations of the Yunnan Snub-nosed Monkey. These populations are located in the Yunling (“Cloudy”) Mountains in southeastern Tibet (Kham) and the northwest of China’s Yunnan Province, between the Zachu (Lancang) and Drichu (Jinsha) Rivers (the headwaters of the Mekong and Yangtze Rivers, respectively).

The Yunnan Snub-nosed Monkey occurs in the Tibetan counties of Dechen (Deqin), Gyalthang (Zhongdian), and Balung (Weixi), in Dechen Prefecture, and Markham (Mangkang) in Chamdo Prefecture. The Monkey occurs in the Chinese counties of Lijiang, Jianchuan, and Lanping. About half of the Yunnan Snub-nosed Monkey’s population is found in nature reserves, including the 1,901 square-kilometer Pema (Baima) Xue Shan (“Snow Mountain”) Nature Reserve.

Eating Habits

Studies have indicated that lichens growing on tree bark, including Bryoria and Usnea spp., constitute the bulk (over 80%) of the Yunnan Snub-nosed Monkey’s diet. Lichen is an abundant food source and it is easy to digest. However, lichen has a relatively low nutritional value and it takes ten to 15 years for lichen to regenerate.

As a result, a troop of Yunnan Snub-nosed monkeys may travel as far as 1,500 metres (.93 miles) in one day and have a home range as large as 25 square kilometres (9.7 square miles). The Monkey may supplement its diet with young leaves, grasses, moss, fruit, pine nuts, acorns, seeds, and/or rodents. In Lijiang county, the Yunnan Snub-nosed Monkey’s diet is composed primarily of bamboo leaves rather than lichens.

Behaviour & Reproduction

The Yunnan Snub-nosed Monkey forages during the early morning and afternoon and naps for about two hours around the middle of the day. Though comfortable on the ground, the Monkey spends most of its time in the trees. The Yunnan Snub-nosed Monkey often rests on rocky outcrops, perhaps because predators are easy spied from such outcrops, or because the sun warms these outcrops up during the day, providing a welcome source of warmth in the cold winter months.

The Yunnan Snub-nosed Monkey is rarely spotted travelling alone; males and females tend to cohabit in troops ranging in size from about 20 to 300 members. No other arboreal primate forms troops as large as those of the Yunnan Snub-nosed Monkey. It is thought that the Monkey’s food competition dynamics determine the size of the troops. Troops are composed of small family groups, each containing about seven members, including one male, two to three females, and their offspring. The Yunnan Snub-nosed Monkey may also form all-male groups.

Male Yunnan Snub-nosed monkeys reach sexual maturity at five to six years of age. Females reach sexual maturity at between four and five years of age. Mating typically occurs in August and September. The Yunnan Snub-nosed Monkey’s gestation period is approximately 200 days. Most births take place from March to April. Each mother gives birth to one, or, occasionally, to two offspring. It is estimated that females only give birth about once every three years. The life span of Yunnan Snub-nosed monkeys is unknown.

Present Status

The Yunnan Snub-nosed Monkey is categorized as Endangered in the 2003 IUCN Red List of Threatened Species and is listed under Appendix I of CITES. The Monkey is under first class protection in China. The Yunnan Snub-nosed Monkey’s population is fragmented into 13 isolated sub-populations. Geographic features make it unlikely that there is any exchange of individuals between these sub-populations. It is estimated that 800 to 1,200 Yunnan Snub-nosed monkeys remain.

Threats to Survival

The Yunnan Snub-nosed Monkey has suffered as a result of habitat loss and intensive hunting and trapping. The Monkey is also caught in snares set for other animals, such as musk deer. The forests in which the Yunnan Snub-nosed Monkey makes its home have been logged and cleared for agriculture.

References

Eudey, A. & Members of the Primate Specialist Group, 2000: Rhinopithecus bieti. In: IUCN, 2003: 2003 IUCN Red List of Threatened

Species, http://www.redlist.org, Aug 2004.

Massicot, Paul, July 2004: Animal Info – Yunnan Snub-nosed Monkey, http://www.animalinfo.org/species/primate/rhinbiet.htm, Sept 2004.

ARKive, Yunnan snub-nosed monkey – Rhinopithecus bieti: More Information – ARKive, http://www.arkive.org/species/GES/mammals/

Rhinopithecus_bieti/more_info.html, Sept 2004.

Flannery, Sean, Oct 2003: Black Snub-nosed Langur (Pygathrix bieti), http://members.tripod.com/uakari/pygathrix_bieti.html, Sept 2004.

By: Environment and Development Desk, DIIR, CTA.