Pygathrix nemaeus

Geographic Range

Red-shanked douc langurs ( Pygathrix namaeus nameaus ) are found innorth and central Vietnam, east-central Cambodia and possibly in China (on the island Hainan). Another subspecies, black-shanked douc langurs ( P. nemaeus nigripes ) are found in southern Vietnam, southern Laos and eastern Cambodia. The subspecies P. nemaeus cinerea occurs in the central highlands of Vietnam. (Lippold, 2001a; Wisconsin Primate Research Center, 2002)

• Biogeographic Regions
• oriental oriental
  • native native

Habitat

Douc langurs are mostly found in tropical rainforest and monsoon forest (both primary and secondary forest). (Lippold, 1977)

• Habitat Regions
• tropical tropical

• Terrestrial Biomes
• rainforest rainforest

Physical Description

Douc langurs ares also known as "costumed apes" for their magnificent colors. Although all members of the species have gray bodies, white tails, and big pot-bellies, the three subspecies can be distinguished by their different color patterns.

Red-shanked douc langurs ( P. nemaeus nemaeus ) have black hind legs with maroon "leg warmers" from knee to ankle. The forearms are white from the elbow to the wrist. The body is gray with tri-colored agouti hairs (marked with black, white and gray). The genitals of males of this subspecies are striking, because of the white scrotum and a penis which is bright red when erect. The perineum is white, and males have patches of white on each side of their white rump patch. These white rump patches are absent on females, allowing easy differentiation of the sexes. The faces of these langurs are also conspicuously marked, with long, white hairs on the cheeks, and reddish-yellow fur on the rest of the face. There are two bands of color over the eyes, one red above one black. (Wisconsin, 2002)

Black-shanked douc langurs ( P. nemaeus nigripes ) have all black hind legs and gray forearms. The gray fur on the chest is lighter than it is elsewhere on the body. The area of the face is colored black, and the white hairs on the cheeks are short. Above the eyes, the two bands of color are reversed from those found in P. nemaeus nemaeus , with the black being found over the red. The perineum of this subspecies is white, and males have characteristic white rump patches, but the scrotum of males is blue. (Wisconsin, 2002)

The remaining subspecies, P. nemaeus cinerea , has mainly gray agouti fur, although the shoulders are black, and the chest, neck, tail, perineum, face, lips, and cheeks are white. The hind feet are colored black, and the forefeet, or hands, are gray with black fingers. The facial skin is goldish-brown, and there are orange markings on the nose and in between the eyes. There is also a band of orange-black color that on the neck that blends into the black on the shoulders. The band of color above the eyes is black. (Wisconsin, 2002)

The young are slightly lighter in color until they reach about 10 months of age. (Kavanagh, 1987)

Adult males weigh an average of 10.9 kg, and the smaller females average about 8.2 kg (Wisconsin, 2002). The average head and body length is 610 to 762 mm, with the tail adding an additional 558 to 762 mm (Nowak, 1999).

Pygathrix nemaeus has a sacculated stomach, which assists them in breaking down plant cellulose and obtaining nutrition from it. The dental formula is 2:1:2:3. (Wisconsin, 2002)

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry
• polymorphic polymorphic

• Sexual Dimorphism
• male larger

Reproduction

Right before mating, both the male and female give each other sexual signals. Males and females both conduct the following display, directed at members of the opposite sex: They drop their jaw forward, lift their eyebrows up then down, then shake their head. The female makes the first move, and has always been observed to initiate the copulation. She lies down on a branch and eyes her chosen mate by looking over her shoulder, a position called "presenting." The male will give a stare back then aproach the female and give a signal if he would like to move some place else to mate or stay where she has chosen. Not all times that a female presents to the male are followed by copulation. Both single and multiple matings have been reported.

(Lippold, 1989; Wisconsin, 2002)

• Mating System
• polygynous polygynous

Female menstrual cycles have an apprximate duration of 28 to 30 days. During estrous, the perineum of the female becomes swollen and red.

After impreganation, gestation lasts an estimated 165 to 190 days. The perineum remains swollen and red. In the wild, births peak between February and June when the fruit is plentiful. The female gives birth to one young and twins are rare. During birth, females often touch their vagina, and move between squatting and stretching positions. Females help the baby to emerge by pulling on it. The infant, in turn, helps to deliver itself by pulling on the mother's fur once its arms are free. After birth, the infant is licked clean, but in captivity, there has been no observed consumption of the afterbirth.

There is no information available on the duration of nursing. Captive females have an interbirth interval around 2 years.

Sexual maturity for females is at the age of 4 years and for males about 4 to 5 years.

(Lippold, 1989; Nowak, 1999; Wisconsin, 2002)

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

The baby clings to its mother from the minute it is born. Infants are typically carried on the mother's belly. Females nurse their infant from both nipples. An orphaned infant was observed being fed by two females in the group and also cared for by a male.

(Lippold, 1989; Wisconsin, 2002)

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • male
    • female
• extended period of juvenile learning

Lifespan/Longevity

Lifespan is 24 years or more in captivity. (Lippold, 1989)

Behavior

This species is arboreal and diurnal. They are usually found in groups of 4 to 15, but has been found in groups of 30 to 50. Occasionally, single individuals of either sex are seen in the forest. Social groups contain one or more adult males and about twice as many females. Each sex apparently has its own dominance hierarchy, and males are dominant over females. When they near maturity, both males and females disperse from their natal groups. (Lipold, 1977; Pham, 1993)

Douc langurs move quadrupedlly, although they often jump from place to place. When jumping, these monkeys push off of a support using their hind limbs, and extending their arms in front and above them. They usually land on their feet. They are reported to move through the forest canopy along established pathways. (Lipold, 1977; Wisconsin 2002)

Douc langurs are playful animals, although juveniles tend to play more than adults. Social play is always accompanied by a grimmace-like "play face," and consists of climbing, jumping, running, hanging and swinging, while touching, pulling, mouthing, wrestling, and chasing a partner. The most active play times are in late morning, early afternoon, and just before bedding down. (Wisconsin, 2002)

In captivity, aggressive interactions are rare (Kavenaugh, 1978).

Like other primates, douc langurs groom one another, and have been observed to share food in captivity (Wisconsin, 2002)

• Key Behaviors
• arboreal arboreal
• diurnal diurnal
• motile motile
• nomadic nomadic
• social social
• dominance hierarchies dominance hierarchies

Home Range

The home range size for these primates in the wild has not been described.

Communication and Perception

Douc langurs are highly social and therefore have a great repetoire of communication patterns, sharing visual, tactile, and accoustic information.

Like many other primates, doucs have a specific "play face" that they display with their mouth open and their teeth partially showing. A grimace with their teeth showing is used to initiate grooming or play. A stare, with raised-eyebrows is used as a threat, and is often responded to with a submissive grimmace. A jaw-thrusting/head shaking face is used to initiate sexual interactions, and presenting is used when a female wishes to engage in copulation.

A low-pitched growl is made to threaten other members of the group. Loud barks and quickly moving around the trees while hitting branches with both their hands and feet can be a sign of threat. (Oates, 1994) This call can also occur during feeding (Wisconsin, 2002). A squeal is often heard during agonistic encounters. A faint, bird-like call, called a twitter, is often used in response to a stare or before social grooming, and is thought to be a submissive signal, allowing another animal to approach without fear of an aggressive response (Wisconsin, 2002).

The main tactile communication channels are social grooming and play. In social grooming, parasites, dandruff flakes and other junk is removed from another monkey's fur with the hands and mouth. Females are the most active groomers, grooming each other, infants and juveniles, and adult males. Grooming is thought to reinforce social bonds between individuals. During play, these monkeys may wrestle, hit, chase, touch, pull on, and mouth one another. (Wisconsin, 2002).

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Douc langurs eat mainly leaves, which comprise about 82% of their diet. Although they prefer young, tender leaves, which are more easily digested than older, tough leaves, the digestion of these leaves is still mainly accomplished by their sacculated stomach, which helps them to break down cellulose. They also consume unripe fruits and their seeds (comprising 14% of their diet), and flowers (4% of the diet). Interestingly, douc langurs don't drink water, instead obtaining the moisture they need from the other foods they eat. (Wisconsin, 2002)

Doucs are very particular when foraging for food. Leaves and fruits are picked and eaten only after close inspection. If leaves are old or fruit is either ripe or overripe it is then discarded. (Pham, 1993)

Plants eaten include: Garcilinia multiflora leaves, Garcilinia oblongifolia leaves, Garcilinia cowa leaves, Garcilinia mangostana leaves, Ficus vasculosa leaves, Ficus chrysocarpa leaves, Ficus retusa leaves, Ficus variegata leaves, Ficus glomerata leaves, Teonogia tonkinensis leaves, Bischofia trifoliata leaves, Phyllanthus emblica leaves, Bacaurea sapida leaves, Dracontomelum duperreanum leaves, Allospondias lakonensis leaves, Choerospondias axillaris leaves, Canarium tonkinense leaves, Canarium album leaves, Canarium nigrum leaves, Andenathera microsperma leaves, Polyalthia nemosalic leaves, Chisocheton paniculatus leaves, Anamixis grandifolia leaves, Averrhoa carambola leaves, Clausenia lancium leaves, Musa coccinea leaves, Castanea mollissma fruits, Castanopsis boisii fruits, Paasania ducampi fruits, Quercus platycalyx fruits, Madhuca pasquieri fruits, Eberhardtia tonkinensis fruits, Ficus vasculosa fruits, Ficus chrysocarpa fruits, Ficus hispida fruits, Ficus retusa fruits, Ficus variegata fruits, Ficus religiosa fruits, Ficus glomerata fruits, Tenongia tonkinensis fruits, Broussonetia papyrifera fruits, Endosperma chinese fruits, Bischofia trifoliata fruits, Phyllanthus emblica fruits, Bacaurea sapida fruits, Dracontomelum duperreanum fruits, Allospondias lakonenis fruits, Choerospondias axillaris fruits, Dubanga sonneratiodes fruits, Canarium tonkinense fruits, Canarium album fruits, Canarium nigrum fruits, Nephellium bassacense fruits, Nephellium chryseum fruits, Euphoea longana fruits, Eugenia brachiata fruits, Peltoforum tonkinense fruits, Polyalthia nemosalic fruits, Chisocheton paniculatis fruits, Averrhoa carambola fruits, Dillenia heterocephala fruits, Clausenia lancium fruits, Caryota urens fruits, Gnetum montarum fruits, Musa coccinea fruits, Grewia paniculata fruits, Peltoforum tonkinense flowers, Adenantheria microsperma flowers, Averrhoa carabola flowers, Garcilinia oblongifolia shoots, Bambusa spinosa shoots, Dendrocalmuys pattelaris shoots, Neohouzeaua dullosa shoots, Garcilinia multiflora buds, Garcilinia oblongifolia buds, Garcilinia cowa buds, Ficus hispa buds, unripe fruits, seeds and flowers.

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Plant Foods
• leaves
• seeds, grains, and nuts
• fruit
• flowers

Predation

The decline in douc langurs is due primarily to hunting by humans. They are hunted both for food and for sport. The forest habitat occupied by this species also experienced intense disruption during the Vietnam war. In areas of Vietnam where defoliants were used during the war, reproduction of P. nemaeus has suffered. (Lippold, 1995; Wisconsin, 2002)

Ecosystem Roles

This monkey is primarily herbivorous. It also eats seeds, and therefore probably contributes to plant dispersal. (Pham, 1993)

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

Some langurs are collected for the pet trade, and some are hunted for food.

• Positive Impacts
• pet trade pet trade
• food food

Economic Importance for Humans: Negative

Pygathris namaeus is not known to have nay negative effects on humans.

Conservation Status

Douc langurs have become endangered due to deforestation, hunting, and the illegal pet trade. They have also been captured and removed from the wild for use in medical research. (Lippold, 1995)

Other Comments

In recent years it has been found that douc langurs are actually more closesly related to proboscis monkeys and snub-nosed monkeys than to other langurs. The word "douc" (pronounced "dook") is an ancient name of Vietnamese origin. (Oates, 1994)

Additional Links

Encyclopedia of Life

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Carla Hara (author), Humboldt State University, Brian Arbogast (editor), Humboldt State University.

References

Kavanagh, M. 1978. The Social Behaviour of Doucs. Primates , 19: 101-114.

Lippold, L. 1977. The douc langur: A time for conservation . New York: Academic Press.

Lippold, L. 2001a. "About Doucs" (On-line). Accessed June 4, 2003 at http://www-rohan.sdsu.edu/faculty/lippold1/about_doucs.htm .

Lippold, L. 2001b. "Conservation" (On-line). Accessed June 3, 2003 at http://www-rohan.sdsu.edu/faculty/lippold1/conservation.htm .

Lippold, L. 1995. Distribution and Conservation Status of Douc Langurs. Asian Primates , 4: 4-6.

Lippold, L. 1989. Reproduction and Survivorship in Douc Langurs. International Zoo Yearbook , 28: 252-255.

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition . Baltimore and London: The Johns Hopkins University Press.

Oates, J. 1994. The Natural History of African Colobines . Cambridge: Cambridge University Press.

Pham, N. 1993. First results on the diet of the red-shanked langur Pygathrix nemaeus in Vietnam. Australian Primatology , 8: 5-6.

Wisconsin Primate Research Center, 30 October, 2002. "Douc Langur ( Pygathrix nemaeus )" (On-line). Accessed June 4, 2003 at http://www.primate.wisc.edu/pin/factsheets/pygathrix_nemaeus.htm .