These monkeys are usually found in groups, ranging in size from four to five individuals to up to 50 (4). These groups may either consist of a single male with females and their young, or have a more multimale-multifemale social system (4). Females become sexually mature at around four years of age (6) and births have been observed to peak during the fruiting season between January and August (4). A single offspring is born after a roughly six-month gestation period (6); young are carried through the treetops on their mothers' front and also by other members of the group (4). Social bonds within these douc groups are vitally important and communication takes place through a wide variety of vocal and visual signals as well as through tactile communication in the form of social grooming (4). The douc's diet is primarily composed of leaves, concentrating on young tender shoots, although fruit, buds and flowers are also consumed (4). These monkeys are arboreal, spending the majority of their time in the canopy of the forest (4).

These colobine monkeys have an extremely striking appearance. At present two subspecies are recognised, the red-shanked douc (Pygathrix nemaeus nemaeus) characteristically has bright maroon legs and reddish patches around the eyes (4). In contrast, the grey-shanked douc (Pygathrix nemaeus cinerea) is less vibrant, with speckled grey legs and orange markings on the face (4). Both have dappled grey bodies, black hands and feet and white cheeks, although the cheek hairs of the red-shanked douc are much longer (4). The black-shanked douc (Pygathrix nigripes) has recently been recognised as a distinct species (1), and it is thought that the little-known P. n. cinerea may also be similarly distinct (2). The long hind limbs and tail allow these monkeys to be wonderfully agile in their treetop habitat (2).

This species occurs in east-central Lao PDR and northern and central Viet Nam and has recently been recorded in northern Cambodia. In Viet Nam, the southern limit is Kon Tum province and the northerly limit is Nghe An Province. This species is the only one of its genus found for certain in Lao PDR (Nadler et al. 2004), ranging from Nam Kading National Biodiversity Conservation Area in Bolkhamsay in the north south to the Xe Kong River in Attapeu Province. Doucs occur south of the Xe Kong, but pelage characteristics are ambiguous making identification problematic (Timmins and Duckworth 1999). The species was recently confirmed for northern Cambodia in Voensei district, Ratanakiri through genetic analysis, however, the extent of the species distribution in Cambodia is still to be determined. It should, however, be noted that these individuals show the same pelage characteristics as those described from southernmost Lao PDR (Timmins and Duckworth 1999; B. Rawson pers. comm.).

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 (Native )

Historic Range:
Cambodia, Laos, Vietnam

Endemic to Indochina (5), the red-shanked douc is found in central Vietnam and east-central Laos, whilst the grey-shanked douc is known only from the central highlands of Vietnam (4).

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)

Average mass: females, 8.2 kg; males, 10.9 kg.

Range length: 610 to 762 mm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry ; polymorphic

Sexual Dimorphism: male larger

Average mass: 9720 g.

Habitat and Ecology

Systems

• Terrestrial

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

Range elevation: 0 to 2000 m.

Habitat Regions: tropical

Terrestrial Biomes: rainforest

Doucs inhabit tropical rain and monsoon forests from sea level to altitudes of 2000 metres above sea level (6).

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.

Plant Foods: leaves; seeds, grains, and nuts; fruit; flowers

Primary Diet: herbivore (Folivore )

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

Ecosystem Impact: disperses seeds

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)

Known Predators:

• humans (Homo sapiens)

Pygathrix nemaeus is prey of:
Homo sapiens

This list may not be complete but is based on published studies.

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 ; tactile ; acoustic

Perception Channels: visual ; acoustic

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

Range lifespan

Status: captivity: 24+ (high) years.

Average lifespan

Sex: male

Status: captivity: 25.0 years.

Average lifespan

Sex: male

Status: captivity: 21.0 years.

Maximum longevity: 26 years (captivity)

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

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)

Breeding interval: The interbirth interval of these monkeys has not been reported.

Breeding season: Breeding occurs from August to December, with births following between February and June.

Range number of offspring: 1 to 2.

Range gestation period: 165 to 190 days.

Range age at sexual or reproductive maturity (female): 4 to 5 years.

Range age at sexual or reproductive maturity (male): 4 to 5 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average birth mass: 393.5 g.

Average number of offspring: 1.

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 ; 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

The following is a representative barcode sequence, the centroid of all available sequences for this species. 

 
There are 2 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
 

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 2
Species: 2
Species With Barcodes: 1

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

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)

US Federal List: endangered

CITES: appendix i

IUCN Red List of Threatened Species: endangered

Current Listing Status Summary

Status: Endangered
Date Listed: 06/02/1970
Lead Region: Foreign (Region 10) 
Where Listed:


Population detail:

Population location: entire
Listing status: E

For most current information and documents related to the conservation status and management of Pygathrix nemaeus , see its USFWS Species Profile

Classified as Endangered (EN A1cd) on the IUCN Red List 2004 (1), and listed on Appendix I of CITES (3). Subspecies: Red-shanked douc (Pygathrix nemaeus nemaeus) classified as Endangered (EN – A1cd); grey-shanked douc (P. n. cinerea) classified as Data Deficient (DD) (1).

Population

Population Trend

Major Threats

Doucs suffer from an extensive level of hunting, for food, live trade and medicinal properties. Despite legal protection, widespread hunting continues (7). Habitat destruction, in the form of logging, is also rife and seriously threatens the future of douc populations (7). The widespread use of defoliants and bombing during the Vietnam War also caused great habitat destruction (6).

Conservation Actions

Doucs are protected from international trade by their listing on Appendix I of the Convention on International Trade in Endangered Species (CITES) (3), and are also protected by law in Vietnam (7). Populations occur within a number of reserves, such as the Bach Ma National Park and the Kong Cha Rang and Kon Khi Kinh Nature Reserves within Vietnam (4). The Douc Langur Project has been undertaking comprehensive surveys of this species in an effort to understand the distribution of populations, which is vital for any successful conservation programme (7). Their studies are also helping to uncover greater knowledge of this still poorly understood primate, such as group size and composition, and social interactions (7). The World Wildlife Fund's (WWF) Indochina Programme is also carrying out vital research into the effectiveness of national parks within Vietnam (5). The effective enforcement of existing laws and national parks will be the key to ensuring the future of this attractive and appealing primate (7).

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

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

Positive Impacts: pet trade ; food