Pygathrix cinerea was described in 1997 on the basis of newly discovered individuals in central Vietnam.
Gray-shanked douc langurs communicate through sound, touch, and vision. Growls can be used as warnings or threats to the other members of the group. Twitters are softer sounds emitted when the animal is being submissive. Tactile communication includes grooming and sparring. The purpose of grooming is to remove parasites and strengthen bonds between group members. In groups with more than one male, females are more likely to groom males. Grooming often occurs just before resting for the night. Sparring is an aggressive behavior and involves slapping, pulling, and grabbing. Visual forms of communication include a variety of postures and facial expressions such as play face, grimace, stare, and a sexual display. Play face is used in play with another member. A grimace is observed as part of submissive behavior towards another member. The stare conveys curiosity or aggression. The sexual display is when the female presents herself to a male signaling that she is ready to copulate or a male signaling to a female by facial movements that he is ready to copulate.
Communication Channels: visual ; tactile ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
The IUCN Red List of Threatened Species classifies this species as being critically endangered and the population trend as decreasing. This is due to hunting and habitat destruction along with other circumstances. In the past, this species was listed as endangered in 2003 and data deficient in 2000. Gray-shanked douc langurs are one of the primates in "Primates in Peril: The World’s 25 Most Endangered Primates." It is estimated that there are only about 700 individuals left. The Vietnam War also had a large negative impact on this species.
US Federal List: no special status
CITES: appendix i
State of Michigan List: no special status
IUCN Red List of Threatened Species: critically endangered
Gray-shanked douc langurs have no known negative effect on humans.
Gray-shanked douc langurs are used for food, traditional medicine, and in pet trade. However, these monkeys are critically endangered and these activities are illegal in most areas.
Positive Impacts: pet trade ; food ; body parts are source of valuable material
Gray-shanked douc langurs may disperse seeds of the fruits they eat by excreting undigested seeds in their feces.
Ecosystem Impact: disperses seeds
Gray-shanked douc langurs are mostly folivorous. However, they also eat plant buds, fruit, seeds, and flowers. They seem to prefer young, tender leaves and fruits that haven’t ripened. They also don’t drink water, but get the water they need from the food that is consumed. Group members may share food.
Plant Foods: leaves; seeds, grains, and nuts; fruit; flowers
Primary Diet: herbivore (Folivore )
Pygathrix cinerea is native to southeastern Asia. They are typically found in the Central Highlands of Vietnam from Quang Nam Province in the north to Binh Dinh and Gia Lai Provinces in the south. A hybridization zone exists with red-shanked douc langurs (Pygathrix nemaeus) on the northern limit of their range.
Biogeographic Regions: oriental (Native )
Gray-shanked douc langurs are largely arboreal, living in evergreen and semi-evergreen primary rainforests. They have been found at altitudes from 900 to 1400 m above sea level where the canopy cover is 80 to 95%. Trees in the forests where they are normally found have a diameter at breast height of 40 to 120 cm and heights of 25 to 35 m. They have also been found in some degraded forests.
Range elevation: 900 to 1400 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: rainforest
Gray-shanked douc langurs typically reaches 24 years or more in captivity, lifespans in the wild are not well documented.
Range lifespan
Status: captivity: 24 (high) years.
The body, crown, and most of the arms of gray-shanked douc langurs are speckled light grey with a paler underside. Their shoulders, upper legs, and part of the rump are marked with white patches. The feet and hands are black while their lower legs are dark speckled grey. The bare skin on their face is yellowish brown, except for the areas around the mouth and chin which is white. Long white fur borders the sides of the face. They have an intermediate eye slant, forming a 15 degree angle from the horizontal. Their throat is white with a broad orange collar bordered by a black line which joins the black patches on their shoulders. Gray-shanked douc langur tails are nearly equal in length to their total head and body length. They are genetically similar to red-shanked douc langurs (Pygathrix nemaeus) but are considered different species due to morphological differences. Compared to black-shanked douc langurs (Pygathrix nigripes), grey-shanked douc langurs are slightly larger, but similar in size to P. nemaeus. Tail length in black-shanked douc langurs (P. nigripes) exceeds that of red and grey-shanked douc langurs by about 100 mm. Males are slightly larger than females, with an average weight of 10.9 kg in males and 8.2 kg in females.
Average mass: 8.2 to 10.9 kg.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry ; polymorphic
Sexual Dimorphism: male larger
The main predators of gray-shanked douc langurs are humans. This species is hunted by humans and their habitat is destroyed for logging and agriculture. Gray-shanked douc langurs have also been observed responding to hunters by hiding in the trees instead of fleeing, which can make them an easy target for skilled hunters. Natural predators have not been reported, but are likely to be large raptors or southeast Asian cat species.
Courtship is initiated with a visual display in which members of the opposite sex thrust their jaw forward and shake the head sideways with small jerky movements. The eyebrows are raised and lowered several times and the upper eyelids are momentarily lowered. Copulation occurs after the other individual gives the same response to this display. The display may be repeated until the female presents herself for mating. Presenting is where the female flexes all four limbs and presses her belly against the substrate. The base of the tail is raised slightly with the head completely raised. The perineum is pointed towards the male. All copulations are preceded by presenting but not every presenting sequence leads to copulation. Copulation begins when the male mounts by positioning the hands on the hips of the female. The male then leans over to the point which the ventral surface is in contact with the female’s dorsal surface. After firmly pressing the feet on the substrate, the male begins to thrust. The process is typically a single mount although double mount sequences have been observed.
Mating System: polygynandrous (promiscuous)
Gray-shanked douc langurs have two-lobed hemochorial placentas with one lobe anterior and the other posterior. Gray-shanked douc langurs give birth seasonally, with births peaking between January and August during the fruiting season. Gestation typically lasts from 165 to 190 days and give birth to a single young. At parturition, females frequently touch their vagina and alternate between squatting and stretching positions. The mother will help delivery by pulling the baby out. Newborns have been recorded with weights between 500 and 720 g. Females become sexually mature at about 4 years old.
Breeding interval: Gray-shanked douc langurs breed once yearly.
Breeding season: Breeding occurs from August to December.
Average number of offspring: 1.
Range gestation period: 165 to 190 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Gray-shanked douc langur young are cared for primarily by their mother, although other members of their social group will help to carry infants. Females nurse and carry their young until independence, although there is no report of time to weaning or independence in the literature.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); extended period of juvenile learning
This species was listed as one of the 25 most endangered primate species by the IUCN in 2012-2014.
The grey-shanked douc langur (Pygathrix cinerea) is a douc species native to the Vietnamese provinces of Quảng Nam, Quảng Ngãi, Bình Định, Kon Tum, and Gia Lai. The total population was estimated at 550 to 700 individuals in 2004.[4] In 2016, Dr. Benjamin Rawson, Country Director of Fauna & Flora International's Vietnam Programme, announced a discovery of an additional population including more than 500 individuals found in Central Vietnam, bringing the total population up to approximately 1000 individuals.[5]
P. cinerea was originally described as a subspecies of P. nemaeus in 1997,[6] but later elevated to species status due to morphological differences. Other research has shown significant genetic differences as well.[7] This species does sometimes hybridize with P. nemaeus.[4][8]
Grey-shanked doucs are very similar in appearance to P. nemaeus. They are light grey with a pale underside. Their feet and hand are black and their shins are a dark grey. The face is brownish orange on top with a white chin. The throat is white and lined on the bottom with an orange-brown collar. Males are slightly larger than females, averaging 10.9 kg. Females average about 8.2 kg.[9]
Grey-shanked doucs are diurnal and primarily arboreal. They move about through trees by jumping and brachiating. In the past they have been found in groups as large as fifty individuals but those numbers have been greatly reduced to 4 to 15 individuals. Males are the dominant gender and dominance hierarchies have been observed while in captivity.[9]
The grey-shanked douc langur communicates using touch, visual communication, and sound. Growls are used to show aggression. They can be used as a threat or warning toward other individuals. A soft, twitter sound is used when being submissive.[10]
Grey-shanked doucs also engage in grooming to remove parasites and to establish and strengthen bonds between group members. This is usually done before resting for the night. Group members will also spar with each other. Sparring is a type of aggressive behavior in which participants will slap, pull, and grab each other.[10]
Visual communication includes facial expressions and various postures. Facial expressions include grimacing, which is used to show submissiveness, play face, which is used to play with another group member, and staring which suggests either curiosity or aggression. Facial expressions are also used during courtship. The male will make faces at the female indicating that he is ready to copulate.[10]
Grey-shanked langurs are primarily folivourous but will also eat other plant parts such as seeds, fruits, and flowers. They prefer young leaves and fruit that has not yet fully ripened.[11]
The breeding season usually occurs between August and December and gestation is about 165 to 190 days. When courting, potential mates will use facial expressions to indicate that they are ready to copulate. One will thrust its jaw forward, shake its head, and raise and lower its eyebrows. The other will then respond with the same action. This may be repeated several times. The female then presents herself to the male.[12]
Births usually occur between January and August, during the fruiting season. The mother will give birth to one offspring weighing 500 g to 720 g. Females are sexually mature at about four years of age.[12]
The grey-shanked douc langur is listed on the IUCN Red List as critically endangered.[13]
Hunting has been a major problem for grey-shanked doucs. They are hunted for bush meat and for traditional medicine purposes. Their bones are used to make a substance called "monkey bone balm" which is thought to improve hemoglobin regeneration and renal function. Monkey bone balm is also believed to treat lack of appetite, insomnia, and anemia. Grey-shanked doucs are also used in the exotic wild life trade. The adults are killed and the infants are taken and sold as pets. The Vietnam War also reduced the population. Soldiers would use the monkeys for target practice. Deforestation and habitat fragmentation are also major threats.
Laws are in place to prevent the destruction of their habitat and to prevent hunting, but although these laws have not always been strongly enforced,[4] that may be changing. In 2016 in the Central Highlands, Gray-shanked douc Langurs were tortured and murdered by Vietnamese troops who posted pictures of it online.[14][15] Researchers have concluded that due to the major deforestation and climate change of these provinces of Vietnam, that the population of the Grey-shanked duoc will sharply decline in the next coming years (Vu et al., 2020). Their species will be pushed into a high mountainous area with little to no resources for survival (Tran et al., 2018)
Studies are under way to learn more about the distribution, range, and behavior of grey-shanked doucs. These studies will help experts to find more ways to conserve this species. A long term study in the Gia Lai Provence is currently being conducted as a part of the Frankfurt Zoological Society's Vietnam Primate Conservation Program.[4] The Frankfurt Zoological Society also works with the Endangered Primate Rescue Center which has an ongoing Captive Breeding program.[2]
On July 3, 2007, it was reported that the WWF and Conservation International had monitored at least 116 of the primates in central Vietnam, increasing its chances of survival.[16]
On March 3, 2016, Fauna & Flora International announced that a new population of over 500 grey-shanked doucs had been discovered in Central Vietnam.[17]
Geographic range in Vietnam The grey-shanked douc langur (Pygathrix cinerea) is a douc species native to the Vietnamese provinces of Quảng Nam, Quảng Ngãi, Bình Định, Kon Tum, and Gia Lai. The total population was estimated at 550 to 700 individuals in 2004. In 2016, Dr. Benjamin Rawson, Country Director of Fauna & Flora International's Vietnam Programme, announced a discovery of an additional population including more than 500 individuals found in Central Vietnam, bringing the total population up to approximately 1000 individuals.
