Douc langur

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TAXONOMY

Suborder: Haplorrhini
Infraorder: Simiiformes
Superfamily: Cercopithecoidea
Family: Cercopithecidae
Subfamily: Colobinae
Genus: Pygathrix
Species: P. cinerea, P. nemaeus, P. nigripes

Other names: P. cinerea: P. cenereus, P. nemaeus cinerea, grey-shanked douc langur, gray-shanked douc langur; P. nemaeus: Rhinopithecus nemaeus, P. n. nemaeus, douc monkey, red-shanked douc langur, red-shanked douc; doek (Dutch); rhinopithèque douc (French); langur jaspeado, mono pigatrix (Spanish); kostymapa, svartbent kostymapa (Swedish); P. nigripes: P. moi, black-shanked douc langur, black-shanked douc, black-shanked douc monkey.

Conservation status:
Critically endangered (P. cinerea), Endangered (P. nemaeus), Endangered (P. nigripes)

Life span: mid-twenties
Total population: P. cinerea: 600-700
Regions: Cambodia, Laos and Vietnam
Gestation: 180-200 days
Height: 59.0 to 63.0 cm (M), 54.5 to 57.0 cm (F)
Weight: P. nemaeus: 11.0 kg (M), 8.44 kg (F)

Groves (2001; 2005) recognizes three species of douc langurs, subsuming a former type, P. moi, under P. nigripes, and separating P. nigripes and P. nemaeus as distinct species. Formerly, P. cinerea was considered a subspecies of P. nemaeus and even then was only recently described in 1997 (Nadler 1997; Brandon-Jones et al. 2004).

Douc is Vietnamese for “monkey” (Lippold & Brockman 1974).

MORPHOLOGY

Douc langur
Pygathrix

The three species of douc langur are each large colobines with a tail about as long as the rest of the body and legs only a little longer than the arms (Nadler et al. 2003). The tail has a tuft of hair at the end (Stevens et al. 2008). The nose is flat and the eyes are diagonally slanted, the degree of which varies between species (Groves 2001; Nadler et al. 2003). Head and body length in P. nemaeus averages 61.0 cm (24.0 in) (M) and 54.5 cm (21.5 in) (F), in P. nigripes is 59.0 cm (23.2 in) (M) and 54.5 cm (21.5 in) (F) and in P. cinerea averages 63.0 cm (24.8 in) (M) and 57.0 cm (22.4 in) (F) (Kirkpatrick 1998; Nadler et al. 2003). Males are typically larger than females (Nadler et al. 2003). In P. nemaeus, males average 11.0 kg (24.3 lb), while females average 8.44 kg (18.6 lb) (Smith & Jungers 1997).

The three species of douc langur are distinguishable based on pelage color differences (Nadler et al. 2003). Perhaps most importantly, the three species are distinguished by the color of their shanks; P. cinereus have grey shanks (the grey-shanked douc langur), P. nemaeus have red shanks (the red-shanked douc langur) and P. nigripes have black shanks (the black-shanked douc langur) (Nadler 1997).

P. cinerea have a gray agouti body, neck, head and arms with dark gray agouti legs (Groves 2001; Nadler et al. 2003). The belly is whitish-gray or almost white and the hands and feet are black (Groves 2001; Nadler et al. 2003). The facial skin is yellow-brown, yellow-orange or light brown with a white mouth and chin with long white whiskers. The throat is white with an orange ring around the neck (Nadler 1997; Groves 2001; Nadler et al. 2003). Facial characteristics are similar in P. nemaeus, but they have a dark agouti belly and white forearms and the eyes slant a bit more than in the other two species of douc langur. The hind limbs are maroon with black fingers, toes and thighs (Groves 2001). There are long white hairs ringing the face (Lippold 1977). P. nigripes has darker, blue-gray facial skin. The eyes have yellow rings around them and slant the least within the genus (Groves 2001; Nadler et al. 2003). The body, upper arms, and head are both dark gray agouti with a dark brown agouti ventrum (Groves 2001; Nadler et al. 2003). The back of the hands are white to the elbow (Nadler et al. 2003).

There can be some variation within species in coloration. For example, in some populations of P. nigripes, individuals have been seen to possess reddish coloration on the legs, a trait more typical of P. nemaeus (Nadler 2008). Further, animals with intermediate traits may be indicative of natural hybridization as individuals have been seen with traits typical of more than one Pygathrix species (Lippold & Vu 1995).

All species have a white tail, but P. cinerea and P. nemaeus have a tassel at the end, while the P. nigripes tail is longer with a nearly absent tassel (Nadler et al. 2003). Male P. nemaeus have a pink penis and a white scrotum as do P. cinerea, while P. nigripes have a blue scrotum and red penis (Nadler et al. 2003). In P. nemaeus, both sexes have a triangle of white pelage around the base of the tail above which males, but not females, have round white spots. This feature can be used to determine the sex of individuals (Lippold 1977).

Wild douc langurs spend a majority of their time arboreally, moving through quadrupedal and brachiation locomotion; traveling single-file through established pathways (Lippold 1998; Nadler et al. 2003). P. nemaeus are not often seen on the ground, however wild P. nigripes have been seen on the ground and may spend up to 20% of their day terrestrially (Lippold 1995; 1998; Lippold & Vu 2008; Hoang et al. 2009). P. nemaeus in captivity primarily move through their environment through brachiation (46%) and quadrupedal walking and running (Nadler et al. 2003; Byron & Covert 2004). Wild P. nigripes move quadrupedally (61%), through leaping (17%), by brachiating (10%), climbing (8%) and dropping (4%) (Rawson 2006). Horizontal jumps in wild P. nemaeus are also seen, with individuals landing feet first (Lippold 1998).

In captivity, Pygathrix have lived into their mid-twenties (Weigl 2005).

RANGE

CURRENT RANGE MAPS (IUCN REDLIST):
Pygathrix cinerea | Pygathrix nemaeus | Pygathrix nigripes

In general, douc langurs of all species are found in eastern Indochina, east of the Mekong River; found in Vietnam (P. cinerea, P. nemaeus, P. nigripes), Laos (P. nemaeus), and Cambodia (P. nigripes) (Timmins & Duckworth 1999; review in Nadler et al. 2003). Roughly, from the north to south, the species of Pygathrix are arranged parapatrically starting with the P. nemaeus, then P. cinerea, and with P. nigripes at the southern end of the generic distribution (Nadler et al. 2003). However, the exact boundaries between all species are unclear and also confounded by the presence of possible hybrid forms and often large gaps in confirmed populations (Nadler et al. 2003). P. nemaeus are the only douc langurs found in Laos, and are found as far north as the center of the country. They range through the central and southern reaches of the country east into Vietnam and south to the Cambodian border (Timmins & Duckworth 1999; Nadler et al. 2003). In Vietnam, the northern limit of P. nemaeus is confirmed as far north as the Pu Mat National Park and south to the Kon Ka Kinh Nature Reserve, but its limits are unclear (Timmins & Duckworth 1999; Nadler et al. 2003). P. nigripes occurs as far north as the Kon Ka Kinh Nature reserve and as far south as the Cat Tien National park. P. cinerea occurs in Vietnam between the distributions other two species, and is present or probably present in the Quang Nam, Gia Lai, Quang Ngai, Binh Dinh, and Kon Tum Provinces (Nadler et al. 2003; Long 2004). The only species that occurs in Cambodia is P. nigripes, with confirmed sightings in the Ratanakiri province and the Mondulkiri Province (reviewed in Nadler et al. 2003).

Both P. nemaeus and P. nigripes occur sympatrically at the Kon Cha Rang Nature Reserve in the Gia Lai Province, Vietnam (Lippold 1998). Douc langurs can live sympatrically with a number of other non-human primates as well. For example, at the Cat Tien National Park in southeastern Vietnam, P. nigripes, is found with pygmy loris (Nycticebus pygmaeus), macaques (Macaca mulatta, M. fascicularis, M. arctoides), silvered langurs (Trachypithecus germaini), and yellow-cheeked crested gibbons (Nomascus gabriellae) (Polet et al. 2004).

It is estimated that there are only 600-700 P. cinerea remaining (Mittermeier et al. 2007; but see also Ha 2004).

HABITAT

Douc langurs are only found in forest habitats. These include old-growth and secondary broadleaf evergreen forest, montane rainforest, wet/dry forests, tropical and semi-tropical evergreen rainforest, submontane and montane evergreen forest, secondary moist forest, monsoon forests, valley forests, sclerophyll evergreen forest, semi-evergreen forest, seasonal lowland forests, and mixed semi-evergreen, mixed humid evergreen forest, and mixed deciduous forest (Lippold 1995; 1998; 1999; Timmins & Duckworth 1999; Lippold & Vu 2002; Ha 2007; Hoang et al. 2009). Douc langurs may also be able to survive in more heavily disturbed forest habitats as well (Ha Thang Long pers comm. cited in Nadler et al. 2003). There are reports of P. nigripes as well as P. nemaeus as high as 1500 meters (4921.3 feet) above sea level and as low as sea level (Eames & Robson 1993; Timmins & Duckworth 1999; Nadler et al. 2003; Ha 2007). Reports at very low altitudes are rare, however, this is nearly meaningless as much suitable habitat at lower altitudes has been cleared and douc langur rarity may be an artifact of extensive human land use and forest clearance (Timmins & Duckworth 1999).

At Phuoc Binh, a douc langur study site in south Vietnam, the average rainfall is over 200 cm (78.7 in), with average highs at 38.8°C (101.8 °F) and lows at 14.2°C (57.6 °F) (Hoang et al. 2009). Across Vietnam (a habitat of all three Pygathrix species), average temperatures range from 27°C (80.6 °F) in south Vietnam grading to an average of 21°C (69.8 °F) in the north of the country. Mountainous areas typically receive more rainfall than in the rest of the country and there are three yearly monsoon seasons (Lippold 1998).

ECOLOGY

Douc langur
Pygathrix

Douc langurs are herbivorous and predominately folivorous (Nadler et al. 2003). In one study in south Vietnam, P. nigripes consumed a range of 152 species of plant, with leaves (especially young leaves) predominating in all seasons, and a lesser reliance on fruit and flowers (Hoang et al. 2009). At this study site on a year-round basis, P. nigripes consumed leaves (54.6%), fruits (19.8%), seeds (9.6%), flowers (14.6%), and other foods (1.5%). Food consumption changed somewhat between the wet and dry seasons, with more fruit eaten in the wet season than in the dry, and correspondingly fewer flowers and leaves in the wet season than in the dry season (Hoang et al. 2009). The species also drinks water while on the ground (Nadler 2008). P. nemaeus mostly eat leaves (especially newly grown), but also eat buds, flowers and fruit (Lippold 1977; Pham 1993a; Lippold 1998). Based on feeding time, P. nemaeus eat leaves (82%), fruit and seeds (14%), and flowers (4%) (Lippold 1998). Animal foods are not eaten (Lippold 1977; 1998).

Wild P. nigripes spend their days on average resting (62%), feeding (27%), traveling (6%), engaged in social behavior (3%) and in other activities (2%). There are peaks in activity, including feeding and traveling early and late in the day (Rawson 2006). Social behaviors include grooming, inter-group aggression, copulation and allomothering (Rawson 2006).

In captivity, P. nemaeus spend their day resting and sleeping (54%) and feeding (23%) (Schwitzer et al. 2002). In the wild, most of the P. nemaeus day is spent moving between food sources and eating, with time also spent sleeping, grooming, or playing (Lippold 1999).

The home range of P. nemaeus is estimated at 1.5-3.5 km² (0.6-1.4 mi²) (Pham 1993b cited in Kirkpatrick 1998).

There is some evidence that P. nemaeus sleeps in larger trees with a thick canopy (Pham et al. 2000 cited in Nadler et al. 2003). Sleeping trees are entered at dusk and are not exited until dawn (Lippold 1999). In captivity, P. nemaeus sleep huddled together (Lippold & Brockman 1974).

More than one species of douc langur may live sympatrically, as is the case at Kong Cha Rang, Vietnam, where P. nemaeus and P. nigripes are both found (Lippold 1995).

Content last modified: September 3, 2009

Written by Kurt Gron.

Cite this page as:
Gron KJ. 2009 September 3. Primate Factsheets: Douc langur (Pygathrix) Taxonomy, Morphology, & Ecology . <http://pin.primate.wisc.edu/factsheets/entry/douc_langur/taxon>. Accessed 2020 July 30.

 

SOCIAL ORGANIZATION AND BEHAVIOR

In general, the majority of douc langur groups are multi-male/multi-female, usually with more females than males (usually around 2 adult females for every adult male), although one-male groups have been observed in P. nemaeus (Lippold 1995; 1998; Nadler et al. 2003; Lippold & Vu 2008; Minh 2008). The group core consists of related females, as well as a lesser number of males and immature individuals including juveniles and infants (Lippold 1999). Group size is variable by location (from only several individuals up to 51), and is affected by the degree of habitat disturbance, with group sizes larger in lesser disturbed habitats which are larger in size (review in Lippold 1998). P. nigripes group sizes average 20 individuals, while P. nemaeus group sizes average 19 individuals (Lippold 1998). Groups are trending towards smaller size as habitats are disturbed further (Nadler et al. 2003). Fission and fusion of P. nigripes groups has been observed in the wild (Minh 2008).

Douc langur
Pygathrix

In the wild, allogrooming occurs more often than autogrooming and adult females groom each other often. Most allogrooming occurs before rest periods or sleep, and especially in the afternoon. Allogrooming sessions may last up to an hour (Lippold 1977).

In the wild, there is a loose dominance hierarchy within douc langur groups, with adult males always dominant to all other group members (Lippold 1977). Hierarchies also occur in captive douc langurs (Lippold 1977; Kavanaga 1978).

In captivity, both females and males between 2 and 4 years old are sometimes forced out of their natal groups (Lippold 1977; Ruempler 1998).

In captive P. nemaeus, agonism is rare, and usually is short-lived when it does occur. Staring and growling indicate aggression and grimacing, twittering and squealing show submission (Kavanagh 1978).

In the wild and in captivity, both adults and immature individuals engage in social play, but adults far more infrequently than the immature individuals, and play is often accompanied by a characteristic play-face (Lippold 1977; Kavanagh 1978). To solicit play, often the head is thrown back with a pseudo-smile on the face, but also by tail pulling, running, jumping, and pulling the ears of another individual. Play may consist of wrestling, chasing and jumping and usually occurs after feeding and before periods of rest (especially in the late morning, early afternoon, and before sleep in the evening). Solitary play is also seen (Lippold 1977).

REPRODUCTION

The female reproductive cycle in P. nemaeus averages 26.4 days, with estrus lasting 1-3 days (Ruempler 1998; Heistermann et al. 2004). Multiple copulations occur during estrus (Ruempler 1998). The rump area changes from white to a red color during estrus (while pregnant, it remains this red color) and copulations continue through pregnancy (Hick 1972; Brockman & Lippold 1975; Lippold 1977; 1998; Ruempler 1998). Interestingly, the male rump also changes to a redder color, responding to females in estrus (Lippold 1998). During pregnancy in captivity, females become more peripheral from the group and spend much time nearby the adult male (Ruempler 1998).

Reproduction and births occur year-round, but there appear to be birth peaks influenced by environmental factors, and within individual groups, several births may occur around the same time (Lippold 1977; 1999).

To solicit mating, a female may face the male and move her head back and forth by pushing her chin forward or she may crouch, facing her anogenital region towards the potential mate, sometimes looking back over her shoulders (Kavanagh 1978; Ruempler 1998). However, either sex may solicit copulation (Lippold 1998). Copulations are dorsalventral, with the male mounting the female from behind and grasping the female with his forearms. In captivity, a male will mate with more than one female in the group (Kavanagh 1978).

In captivity, P. nemaeus males reproduce for the first time between 5-8 years old while females reproduce first between 5-7 years old (Ruempler 1998). Gestation can only be estimated at between 180 and 200 days, due to multiple copulations between partners in a single estrus, although a single captive female in one study had a gestation of 210 days (P. nemaeus) (Brockman & Lippold 1975; Lippold 1981; Ruempler 1998). The average inter-birth interval is 24 months in captivity (Ruempler 1998).

PARENTAL CARE

At birth, a P. nemaeus male weighed 324g (11.4 oz), while females average 463g (16.3 oz) (Ruempler 1998; Smith & Leigh 1998). P. nemaeus infants are hairy at birth (chestnut-colored with black hands and feet), but in contrast to adults their face is black, with only lighter stripes below their eyes. This coloration changes to adult coloration between 8-12 months old (Hick 1972; Ruempler 1998). The eyes are open at birth and infants are usually singletons (Hick 1972; Ruempler 1998). In captivity, P. nemaeus births occur mostly in the early evening and not during the day (Ruempler 1998). Infants are carried ventrally both by the mother and other members of captive douc langur groups (Kavanagh 1978; Ruempler 1998). Climbing starts by day 7 of life, and hanging by the feet at 14 days. In captivity, by 18 days old, infants start grasping solid food and are eating leaves and fruit by 60 days old (Brockman & Lippold 1975; Ruempler 1998). Weaning starts at around 12-15 months (Ruempler 1998).

Allomothering is observed in wild P. nigripes (Rawson 2006).

COMMUNICATION

In P. nemaeus, threats are communicated by flattened ears and a forward stretched neck (Ruempler 1998). Aggression is signaled by the “stare” in which the eyes are opened all the way, raised eyebrows, and sometimes thrusting forward of the jaw (Kavanagh 1978). Submission or non-hostility is indicated by the “grimace” in which the eyes and mouth are opened so the teeth are visible (Kavanagh 1978).

P. nemaeus emit a “threat bark” when they are surprised, grunts when satisfied, excitement calls, and screams when frightened (Lippold 1977; Ruempler 1998). Twittering and squealing indicate submission, while growling indicates a threat (Kavanagh 1978).

Content last modified: September 3, 2009

Written by Kurt Gron.

Cite this page as:
Gron KJ. 2009 September 3. Primate Factsheets: Douc langur (Pygathrix) Behavior . <http://pin.primate.wisc.edu/factsheets/entry/douc_langur/behav>. Accessed 2020 July 30.

INTERNATIONAL STATUS

CITES: Appendix I (What is CITES?)
IUCN Red List: P. cinerea: CR; P. nemaeus, P. nigripes: EN (What is Red List?)
Key: CR = Critically endangered, EN = Endangered, EN = Endangered
(Click on species name to see IUCN Red List entry, including detailed status assessment information.)

Douc langur
Pygathrix

In general, Laos harbors the largest conservable P. nemaeus populations, predominantly due to less habitat fragmentation. The largest populations of the species likely reside within its borders (Timmins & Duckworth 1999). P. cinerea are listed as one of the World’s 25 Most Endangered Primates by the IUCN Primate Specialist Group and there are likely less than a thousand individuals in existence (Ha 2004; Mittermeier et al. 2007).

In general, the main threats to douc langurs are hunting, the loss of their habitat, and trade across borders, even though doucs are considered protected (Lippold 1999; Timmins & Duckworth 1999). However, many protected areas are under-staffed and staffs are under-equipped, limiting the protection they actually afford to douc langurs (Lippold 1995). In Vietnam, enforcement of protective laws rarely occurs (Lippold & Vu 1998). In addition, literally millions of people live within protected areas within Vietnam (Lippold 1998).

CONSERVATION THREATS

Threat: Human-Induced Habitat Loss and Degradation

Habitat destruction is a main threat to douc langurs and cutting of trees for firewood is the predominant threat habitats (Lippold 1998; Lippold & Vu 1998). Forest exploitation for a number of uses (including firewood for charcoal, resins, palm leaves, cycad and rattan) degrades douc langur habitats and damages food trees (Lippold & Vu 2008). Resin is collected from favored food trees, weakening them, and making them susceptible to termites, weather and natural disasters (Lippold & Vu 2008). Logging occurs for coffee, rubber, fruit tree, and cashew agriculture, but also other types of plantation agriculture (Lippold & Vu 2002; Ha 2004; Nadler et al. 2007). In Laos, habitat loss due to swidden agriculture and commercial logging threatens populations as it fragments populations and affects the ecology of the species (Timmins & Duckworth 1999). In Vietnam, logging is sometimes prevented in National Parks, but in nearby areas it does occur, destroying potential corridors between populations (Ha 2007). In addition, logging continues both illegally (including by the Vietnamese army) and legally (Lippold & Vu 1998; Ha 2004). Agricultural forest clearance and logging also threaten populations of P. cinerea (Mittermeier et al. 2007).

Development of habitats for tourism also threatens them in multifaceted ways. For example, at Son Tra, Vietnam, tourism development has cause new roadways to be built which has fragmented habitats. The road-building itself causes hunting, as road crews sometimes take douc langurs to eat (Lippold & Vu 2008).

Threat: Harvesting (hunting/gathering)

Hunting and trapping can be the main threat to some douc langur populations, even in protected areas (Lippold 1998; Lippold & Vu 1998; Timmins & Duckworth 1999; Lippold & Vu 2008). Traps which have been placed for other species threaten douc langurs, as well as traps specifically designed to catch primates (Lippold & Vu 2008). P. cinerea are hunted even within protected areas and especially by the use of snares (Ha 2007; Mittermeier et al. 2007). Further, some traditional hunting of the grey-shanked langur does occur and sometimes, traditional hunters supply primates for consumption outside of forested areas (Lippold 1999; Ha 2007).

Gathering of douc langurs for trade is also one of the predominant threats to the species (Timmins & Duckworth 1999). They are gathered and certain body parts are used as medicines (including to make “monkey balm”), and infants are also collected as pets or for food (Davidson et al. 1997 cited in Timmins & Duckworth 1999; Lippold 1998; Lippold & Vu 2002). Particularly, adults are often shot for food and their infants are sold alive as pets or into international trade (especially for export to China), which is a widespread problem (Lippold 1995; 1999). For example, douc langurs are exported from Laos to both Thailand and Vietnam (reviewed in Timmins & Duckworth 1999). Also, P. nemaeus have been illegally purchased by Chinese zoos (Nadler et al. 2007).

Threat: Human Disturbance

P. nemaeus present in areas used as military installations have been shot as target practice (Lippold & Vu 2008). The Vietnam War was a significant factor in the destruction of douc langur habitats in the mid-twentieth century as well (Lippold 1977). In addition, habitats to which Agent Orange (a chemical defoliant) were applied during the war no longer contain douc langurs, even when regenerating (Lippold 1995).

Overpopulation by humans is also a potential threat, as individuals are being resettled in areas that were formerly sparsely populated, and often douc langur habitats (Lippold & Vu 1998).

LINKS TO MORE ABOUT CONSERVATION

CONSERVATION INFORMATION

CONSERVATION NEWS

ORGANIZATIONS INVOLVED IN Pygathrix CONSERVATION

Content last modified: September 3, 2009

Written by Kurt Gron.

Cite this page as:
Gron KJ. 2009 September 3. Primate Factsheets: Douc langur (Pygathrix) Conservation . <http://pin.primate.wisc.edu/factsheets/entry/douc_langur/cons>. Accessed 2020 July 30.

The following references were used in the writing of this factsheet. To find current references for Pygathrix, search PrimateLit.

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Content last modified: September 3, 2009

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Pygathrix nemaeus
Photo: Anna Halko-Angemi
Pygathrix nemaeus
Photo: Anna Halko-Angemi
Pygathrix nemaeus
Photo: Christina Oliphant
Pygathrix nemaeus
Photo: Christina Oliphant
Pygathrix nemaeus
Photo: Richard Frazier
Pygathrix nemaeus
Photo: Sheri Jurkiewicz

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