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. (Francis, 2008; Long, 2007)
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. (Covert, et al., 2008; Francis, 2008; Long, 2007)
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. (Kavanagh, 1978)
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. (Ademmer, et al., 2002)
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.
Gray-shanked douc langurs typically reaches 24 years or more in captivity, lifespans in the wild are not well documented. (Lippold, 1989)
Gray-shanked douc langurs are arboreal, diurnal primates that move by jumping and brachiating. They sometimes use a suspensory posture while eating leaves from small tree branches. Their diet is mostly young leaves and this creates a need for locomotion that allows them to reach the ends of small tree branches. Gray-shanked douc langurs live in small, social groups of 4 to 15 individuals and a female to male ratio of two to one. They have also been seen alone and in large groups of up to 50. Males are the dominant sex and dominance hierarchy have been observed in captivity. Social interactions are complex, ranging from aggression to playing. (Covert, et al., 2008; Primate Info Net, 2009)
The home range size of gray-shanked douc langurs is not reported in the literature.
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. (Primate Info Net, 2009)
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. ("Southeast Asian Mammal Databank", 2008; Primate Info Net, 2009)
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. (Nadler, 1997)
Gray-shanked douc langurs may disperse seeds of the fruits they eat by excreting undigested seeds in their feces. (Primate Info Net, 2009)
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. (Nadler, 2001)
Gray-shanked douc langurs have no known negative effect on humans.
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. (Aguiar, et al., 2007; Ngoc Thanh, et al., 2008; Primate Info Net, 2009)
Matt Berger (author), Penn State University Park, Jacqualine Grant (editor, instructor), Penn State University Park, Tanya Dewey (editor), Animal Diversity Web.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
an animal that mainly eats leaves.
A substance that provides both nutrients and energy to a living thing.
An animal that eats mainly plants or parts of plants.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
found in the oriental region of the world. In other words, India and southeast Asia.
the business of buying and selling animals for people to keep in their homes as pets.
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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