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TAXONOMY
Suborder: Haplorrhini
Infraorder: Simiiformes
Superfamily: Cercopithecoidea
Family: Cercopithecidae
Subfamily: Colobinae
Genus: Semnopithecus
Species: S. ajax, S. dussumieri, S. entellus, S. hector, S. hypoleucos, S. priam, S. schistaceus
Other names: Hanuman langur, sacred langur, Indian langur; S. ajax: dark-eyed Himalayan langur, Himalayan gray langur, Kashmir gray langur, western Himalayan langur; S. dussumieri: Dussumier’s Malabar langur, southern plains gray langur; S. entellus: Bengal hanuman langur, common langur, entellus langur, gray langur, Hanuman langur, northern plains gray langur, true langur; Hanuman langur (Danish); hoelman (Dutch); hulmaani (Finnish); entelle; houleman (French); hulman (German); langur, hanuman (Hindi); entello (Italian); gooni (Kumaun Hindi); houlemán, langur común, langur hanuman (Spanish); grå hulman, hanumanlangur, himalayahulman, hulman, hulmanbladapa (Swedish); S. hector: gray langur, Hanuman langur, lesser hill langur, Tarai gray langur; S. hypoleucos: black-footed gray langur, dark-legged Malabar langur; S. priam: Madras gray langur, tufted gray langur; S. schistaceus: central Himalayan langur, Nepal gray langur.
Total population: approx. 300,000
Regions: South Asia
Gestation: 200 days
Height: 61.1 to 68.9 cm (M & F)
Weight: 12.5 to 17.7 kg (M & F)
The taxonomy of the gray langur is debated, and until recently, all gray langurs were subsumed under one species, S. entellus, or included as subspecies of S. entellus (Bennett & Davies 1994; Groves 2005). In some cases the species is still considered monotypic with different populations separated out subspecifically. Groves (2005) recognizes 7 species and his taxonomy is followed herein.
The gray langur is sometimes referred to as the Hanuman langur, named after the monkey-god Hanuman. As such, gray langurs are considered sacred in the Hindu religion (Roonwal & Mohnot 1977).
MORPHOLOGY
In general, gray langurs are large monkeys but vary greatly in body size between species and location (Roonwal & Mohnot 1977; Bennett & Davies 1994). A rough gradient of decreasing size and mass exists as one moves further south in the gray langur distribution (Roonwal 1981; Napier 1985; Ray 2000). In addition, there is variation in the degree of sexual dimorphism, with some species showing profoundly larger males than females, while others show only nominal differences (Groves 2001). The overall body color of all species is grayish with a black face and ears, and a tail that is always longer than the body (Roonwal & Mohnot 1977; Roonwal 1981; Groves 2001). Northern and southern populations of gray langur differ in their method of carrying their tail, with northern populations carrying their tail pointed forward, while southern populations do so with the tail pointed backwards (Roonwal 1979; Roonwal et al. 1984). The dividing line between the two populations is roughly along a line across the Indian peninsula (Roonwal et al. 1984).
S. ajax is very large in body size. It has a yellowish-white coloration, especially on the ventrum and some brown on the dorsum and limbs with the forelimbs darkest (Groves 2001; Brandon-Jones 2004). S. dussumieri is one of the smaller gray langurs and is gray-brown or mauve with a yellowish ventrum and is one of the smaller gray langurs. The upper hindquarters are whitish and the head is creamy colored. The fingers and toes are black and sometimes the extremities and forearms are also. Overall, S. entellus has a reddish or orangish tinge, with yellow sides and a brownish or gray-brown back (Groves 2001; Brandon-Jones 2004). Body size is around average for the gray langurs (Brandon-Jones 2004). The belly is red-gold (Groves 2001). S. hector has a white head and is overall grayish yellow, yellowish-white, or pale orange with brownish limbs, a grayish-brown back and a whitish ventrum with pale paws (Groves 2001; Brandon-Jones 2004). S. hypoleucos is a mid-sized gray langur and is purplish-brown with black limbs and an orangish belly. In addition, the body hair is longer than that on the limbs, and the tail is black (Groves 2001). S. priam is pale brown-gray, with a whitish head and a creamy yellow ventrum (Groves 2001; Brandon-Jones 2004). The body is mid-sized for a gray langur (Brandon-Jones 2004). The hands and feet are lighter than the body, the tail has a white end and the feet are sometimes almost white (Groves 2001). S. schistaceus are mid-sized gray langurs that dark brownish with a whitish head, ventrum, upper hindquarters, and tip of the tail. Further, they have a larger body size than others among the gray langurs (Groves 2001).
The combined head and body lengths of both sexes of S. schistaceous average 68.9 cm (27.1 in) but females are typically somewhat smaller than males. Males average 17.7 kg (39.0 lb) and females average 15.8 kg (34.8 lb) (Roonwal 1979). S. ajax with both sexes have a combined head and body length that averages 67.1 cm (26.4 in) and weigh on average 17.7 kg (39.0 lb). S. entellus average 63.9 cm (25.2 in) and weigh an average of 12.5 kg (27.6 lb). The head and body length of S. priam averages 61.1 cm (24.1 in) and average 12.8 kg (28.2 lb) (Roonwal 1981).
Gray langurs move primarily in a quadrupedal fashion both terrestrially and arboreally, about half of the time in each mode (Ripley 1967; Sugiyama 1976; Vogel 1977). Running is preferred to walking, both on the ground and in the trees, although both are seen. Other forms of locomotion include bipedal hops, climbing and descending supports with the body upright, and leaping (Ripley 1967; Dunbar & Badam 1998). Horizontal leaps may be 3.7-4.6 m (12.0-15.0 ft), while descending leaps may be up to 10.7-12.2 m (35-40 ft) (Ripley 1967). Further, when moving terrestrially at a medium speed, gray langurs will sometimes intermittently walk then run several steps, each in an irregular pattern (Grand 1976). Gray langurs have been seen swimming after accidentally falling into water (Agoramoorthy 1986).
In captivity, gray langurs can live into their early thirties, and in the wild males may live past 18 years old and females past 30 (Borries et al. 1991; P. Dolhinow pers comm. cited in Sommer et al. 1992; Rajpurohit et al. 1995; Weigl 2005). In captivity, females can be reproductively active well into their late 20s (P. Dolhinow pers comm. cited in Sommer et al. 1992).
RANGE
CURRENT RANGE MAPS (IUCN REDLIST):
Semnopithecus ajax | Semnopithecus dussumieri | Semnopithecus entellus | Semnopithecus hector | Semnopithecus hypoleucos | Semnopithecus priam | Semnopithecus schistaceus
Among the colobines, gray langurs have the widest distribution, found in Bangladesh, Bhutan, China, India, Nepal and Pakistan; ranging from north India in Kashmir and the Himalayas in Nepal, Bhutan, and Tibet south to Sri Lanka, east to Bangladesh and west to the Indus valley in Pakistan (literature reviewed in Roonwal & Mohnot 1977; Rajpurohit 1992; Wang et al. 1999; literature reviewed in Ray 2000; Groves 2001; Brandon-Jones et al. 2004; Choudhury 2008). Gray langurs may exist in Afghanistan as well (Brandon-Jones 2004).
Among the species, S. ajax is found between the Himalayas in northern India and Pakistan. S. dussumieri is found throughout west-central and southwestern India. S. entellus ranges between lowland Pakistan in the west and the Godavari and Krishna Rivers in central India and north to the Ganges River. S. hector ranges from northern India in Kumaun near the western border of Nepal to Katmandu in central Nepal, restricted to the Himalayan foothills. S. hypoleucos is only found in the Kerala coastal region of southwestern India. S. priam is found on the island of Sri Lanka as well as on the mainland of southeastern India. Finally, S. schistaceus ranges in the Himalayas from central Nepal to Tibet near Mount Everest to areas of China near northwest Bhutan (Groves 2001).
HABITAT
Gray langurs are flexible in their habitat choice and, correspondingly, are found in a large range of habitat types and environments (Sugiyama 1976; Oppenheimer 1977; Bennett & Davies 1994). They range from arid habitats to tropical evergreen rainforests, including all forest types excepting dense rain forest and range higher than 4000 m (13123.4 ft) above sea level including areas that receive winter snows. Other habitats include evergreen forest, moist deciduous forest, broadleaf forest, subtropical pine forest, riverine forest, dry open scrub, open park woods, desert areas, mountain foothills, mountain forests, Himalayan oak-coniferous forests, dry deciduous habitats, subtropical evergreen forest, temperate coniferous forest, sub-alpine forest, grasslands, meadows, scrub, scrub forests, mixed grasslands and forest, moist deciduous habitats and even villages, towns, residential areas, tourist areas, temple grounds orchards and areas under cultivation (Sugiyama 1976; reviewed in Vogel 1977; Bishop 1979; Roonwal 1981; Curtin 1982; Mathur & Manohar 1990; Newton 1992; reviewed in Bennett & Davies 1994; Mathur & Manohar 1994; Pirta et al. 1997; Chaudhuri et al. 2004; Rajpurohit et al. 2004). They are rarely found in evergreen forests (Bennett & Davies 1994). They adapt well to habitats in close proximity to humans, living even in built-up areas including markets (Bennett & Davies 1994). In fact, gray langurs inhabit the city of Jodhpur, India, a city of over a million inhabitants (Waite et al. 2007). The rainfall in their habitats also varies greatly; from under 10 cm (3.9 in) annual precipitation to over 200 cm (78.7 in) (Oppenheimer 1977). Among the species, S. dussumieri is found in moist deciduous forest, dry scrub forest, dry scrub desert, dry deciduous forest and tropical broadleaf forests. S. schistaceus is found in temperate coniferous and broad leaf forests (reviewed in Kirkpatrick 2007). S. ajax is found in temperate oak-coniferous forests which encounter snowfalls during the winter (Oppenheimer 1977).
Himalayan populations experience strong seasonality in their habitat between cold winters (temperatures can fall as low as 19.4 °F (-7 °C)) and rainy summer monsoons (Bishop 1979; Curtin 1982). In contrast, at a different long-term study site at the Kumbhalgarh Wildlife Sanctuary in Rajasthan, India, summer temperatures usually range between 30 and 35 °C (86 and 95 °F) and as high as 46 °C (114.8 °F) while during the winter average temperatures are around 5 °C (41 °F) and can get as cold as 2 °C (35.6 °F). Average rainfall is 72.5 cm (28.5 in) at this study site (Chhangani 2002b).
ECOLOGY
Gray langurs are mostly vegetarian but are not exclusively leaf-eating like some colobines (Vogel 1977). Over their distribution, gray langurs have variable diets by location, habitat type, as well as season and receive differing levels of provisioning by humans. In natural, non-provisioned populations, the diet is composed of leaves (52-61%), fruits (15-25%), flowers (4-13%), insects (0.4-3%), and other foods such as bark, gums, and soils (9-16%) (reviewed in Koenig & Borries 2001). A variety of plant foods and species are eaten across species (over 200), including deciduous and evergreen leaves, as well as leaf buds, herb leaves, coniferous needles, fruits, fruit buds and evergreen petioles (reviewed in Roonwal & Mohnot 1977; reviewed in Vogel 1977; Khan 1984; Chalise 1994-1995; Sayers & Norconk 2008). Trees and shrubs predominate, followed by herbs and grasses and finally other plant types (reviewed in Vogel 1977). Other foods which are consumed include shoots, seeds, mosses and lichens, coniferous cones, underground plant parts, spider webs, termite mounds, cremated human remains and bones, fern rhizomes, grass, bamboo, plants under cultivation, such as potatoes, spinach, cauliflower, cotton, eggplant and radishes, and provisioned foods given by humans, such as wheat cakes, millet, and other human foods (reviewed in Oppenheimer 1977; reviewed in Roonwal & Mohnot 1977; Khan 1984; Sayers & Norconk 2008). Gray langurs sometimes drink water, but not from leaves in trees or muddy water (Oppenheimer 1977; reviewed in Roonwal & Mohnot 1977; Starin 1978; Newton 1992). However, most water is attained from the food they ingest (Starin 1978). Rarely, resins are eaten (Newton 1992). In general, gray langurs are not picky and if a food is available and suitable, a gray langur will eat it (Koenig & Borries 2001). Usually, more mature leaves are eaten than young leaves (Koenig & Borries 2001). Bark is eaten mostly in times of food scarcity and rarely at other times (Sharma 2001).
Gray langur diets change seasonally as well with shifts in food abundance. This is the case with the population (probably S. schistaceus) in the Langtang National Park, Nepal (Sayers & Norconk 2008). At this highly seasonal location, low-abundance winter (December-March) foods include leaf buds, ripe fruit, and the fallback food of evergreen mature leaves. During spring (April-May) food includes largely deciduous young leaves and bark. Summer monsoon foods (June-September) include deciduous mature leaves and fruits. Fall (October-November) foods include deciduous mature leaves, unripe fruit, and herbs, and underground plant parts (Sayers & Norconk 2008). With seasonal changes in availability otherwise less-important foods can also become more important, as is the case with insects during the monsoon (Srivastava 1991). In one study, the consumption of insects approached almost a quarter of feeding time at the beginning of the yearly monsoon at a study site in central India (Newton 1992).
Gray langurs are diurnal, spending their nights in sleeping trees (usually more than two near to one another) in one study averaging around 12 m (39.4 ft) tall, usually selecting the highest branches (Ramakrishnan & Coss 2001; Chhangani 2002b). In less natural habitats, gray langurs have used old hunting towers or high-tension electric poles for sleeping (Sharma 2002).
On an annual basis in undisturbed forest in the central Indian highlands, gray langurs spend their time feeding (25.7%), idle (41.8%), moving (13.1%), clinging (7.9%), and allogrooming (6.0%) (Newton 1992). In Bangladesh, near the eastern limits of their distribution, gray langurs spend their days sitting (44.3%), moving (16%), feeding,(14%), playing (11.2%), social grooming (7.1%) and the rest of the day in other activities (Ahsan & Khan 2006). Himalayan gray langurs in Nepal spent their time feeding (39.8%), resting (29.2%), traveling (17.5%), grooming (9.5%), and huddling (3.2%) with the rest of their time spent in other activities (Sayers & Norconk 2008). However, there are seasonal shifts in activities, as is the case at Ambagarh Reserve Forest, Jaipur, India, where summer activities are concentrated in the morning and afternoon while in the winter most activity is at midday (Mathur & Bhatnagar 1993). Gray langurs do not follow a consistent daily regimen (Rajpurohit & Rajpurohit 2002). In addition, under provisioning, gray langurs become less active (Rajpurohit & Rajpurohit 2002).
Home ranges, like other aspects of gray langur ecology are also quite variable; from 0.07 to 22 km² (0.03 to 8.5 mi²) with the home ranges of all male groups typically larger than those of other types (Mathur & Manohar 1993; literature compiled by Chhangani & Mohnot 2006). Long-term data indicate that groups usually do not alter or move their home ranges (Newton 1994). Himalayan gray langurs (probably S. schistaceus) travel an average of 1.5 km (0.9 mi) each day annually with the longest traveled days during the winter (Sayers & Norconk 2008).
In some areas, wild cattle and deer wait under arboreally feeding gray langurs and eat foods dropped by the primates (Punekar 2002). Further, nymphs of the insect Leptocoris augur may rely on langurs to crack the hard outer casings of preferred fruits and congregate below langur feeding locations to feed (Newton 1984).
Gray langurs live sympatrically with a number of other primates across their distribution, including Macaca sp. and Trachypithecus johnii (Singh et al. 2000; Ramakrishnan & Coss 2001; Choudhury 2008; Vasudev et al. 2008). Close associations between Himalayan populations of gray langurs and rhesus macaques (Macaca mulatta) have been seen, and a female langur has even been seen suckling an infant rhesus macaque (Das & Sharma 1980).
Predators of gray langurs include leopards (Panthera pardus), dholes (Cuon alpinus) and tigers (P. tigris) (Boggess 1976; Ross 1993; Andheria et al. 2007). Wolves (Canis lupus) may be a predator, as may be golden jackals (Canis aureus) (Boggess 1976; Newton 1985). Upon sighting snakes, gray langurs have been seen to mob the reptiles (Srivastava 1991).
Content last modified: October 28, 2008
Written by Kurt Gron.
Cite this page as:
Gron KJ. 2008 October 28. Primate Factsheets: Gray langur (Semnopithecus) Taxonomy, Morphology, & Ecology . <http://pin.primate.wisc.edu/factsheets/entry/gray_langur/taxon>. Accessed 2020 July 22.
SOCIAL ORGANIZATION AND BEHAVIOR
Gray langur groups are extremely variable in both their size and composition, especially between different habitats and between years (Mohnot & Srivastava 1992; Rajpurohit 1992). In general however, the social system can be both polygynous and multi-male/multi-female (Borries et al. 1991). But, there is evidence that multi-male groups are an atypical situation, and merely a transition period following a takeover during the mating season and such groups soon split into single-male and all-male groups (Mathur & Manohar 1990). Further, multi-male groups usually turn into single-male troops around the mating season (Newton 1987). Group sizes can range from 2 to 90 and sometimes more than a hundred animals, although such agglomerations are rare and usually groups are much smaller (reviewed in Newton 1988; Mohnot & Srivastava 1992; Mathur 1996; Schülke 2001; Chhangani 2002a; see Vasudev et al. 2008).
There are three main types of group; uni-male bisexual groups (one adult male, females, juveniles), multi-male bisexual groups (males and females of all age/sex classes), and all-male groups (Rajpurohit 1992; Newton 1994; Chhangani 2002a). However, among study sites there is great variability, with some populations mostly having only multi-male bisexual groups, while in others the only type of bisexual group present is the uni-male group (Mohnot & Srivastava 1992; reviewed by Rajpurohit 1992). All-male groups are typically smaller than other types of gray langur groups and can contain adults, subadults, and juveniles (Rajpurohit 1992). In some populations groups are stable and uni-male the majority of the time (Sommer & Rajpurohit 1989). Groups containing females are matrilineal (Mohnot & Srivastava 1992). If provisioned by humans, group sizes are generally larger than those that are unprovisioned (Mathur & Manohar 1986). There is long-term evidence that female membership in groups is stable, as are home ranges, but with larger group size, this is less true (Newton 1994; Koenig 2000).
Linear rank hierarchies are formed in both all-male groups as well as between individuals of each sex in mixed-sex groups (Srivastava & Mohnot 1992; Rajpurohit et al. 1995; Koenig 2000; Rajpurohit & Rajpurohhit 2005; Rajpurohit 2008). In all-male groups, rank is determined mostly by displacement of another animal, but also through chasing, fighting, copulatory success, and harassment (Rajpurohit 2008). Occasionally, all-male groups will temporarily split into sub-groups, probably for the purpose of looking for resources such as females and food (Rajpurohit 1995). Within the female dominance hierarchy, the females in the best physical condition were more likely to be higher-ranking (Koenig 2000). In addition, the youngest sexually mature females are usually the highest-ranking, and decline in rank as they age (Borries et al. 1991).
Relationships within a group between the adults vary by sex. Among themselves, males may be peaceful, cooperative or agonistic, while males and females are usually calm and cooperative with each other. Female-female relationships are typically positive and they will feed, move, rest, groom one another, embrace, and greet each other. In general, females usually groom males more than they themselves are groomed by males (Ahsan & Khan 2006). Between females, grooming is directed both up and down the dominance hierarchy but higher ranking individuals groom others and receive grooming more than lower ranking individuals (Borries et al. 1994). Within a group, aggressive and submissive interactions are more often between high-ranking members (Rajpurohit & Rajpurohit 2005). Post-conflict, gray langurs typically avoid each other (Sommer et al. 2002).
Intergroup relationships are usually agonistic, and typically consist of high-ranking males displaying, vocalizing, and fighting (Ahsan & Khan 2000). Within a group, there are several types of aggression, including visual and tactile threat gestures, displacement, charges and chases, and physical attacks (Bogges 1976).
The method of replacement of a resident male in a uni-male group differs between populations. In some groups it occurs quickly while in other groups it is a drawn-out process (Rajpurohit et al. 2003). However, the speed and method of group male reorganization may vary within a single population (Newton 1987). The vast majority of male rank changes are associated with emigration and immigration and usually, males leave troops as a result of aggression from non-group males (Agoramoorthy 1994; Borries 2000). In one population, the mechanism of male replacement usually started with an invasion of a uni-male group by a multi-male group and the subsequent replacement of the resident male. Subsequently, there is a period of multi-male organization ended by the all-male group leaving a new male in the single-male group (Rajpurohit 1993). It is estimated that the average time a male spends in a single-male group is 45 months (Newton 1987).
Female gray langurs typically stay in their natal group for the duration of their life while males emigrate (Newton 1994; Borries 2000; Rajpurohit & Rajpurohit 2006). Males emigrate from their natal groups before adulthood, but the timing of this event varies among populations. For example, in one study males emigrated at an average of 30.5 months of age while in a different study, the average was around six years old (Borries 2000; Rajpurohit et al. 2006).
Gray langurs will attempt to revive sick individuals by sitting around them, shaking them, jumping on the abdomen, and sitting on the ailing langur (Mathur & Lobo 1987).
REPRODUCTION
Because of the variability of the gray langur social systems, mating can be both polygynous and polygamous (Borries et al. 1991). In one-male groups, the resident male usually fathers almost all of the offspring in the group, while in multi-male groups the alpha-male sires the most, followed by other group males and even non-group males (Launhardt et al. 2001). Higher-raking females have significantly higher reproductive success than lower-ranking individuals (Borries et al. 1991).
Female gray langurs show no external signs of reproductive state, and will mate during all reproductive states including when pregnant. This is perhaps to confuse males about parenting and to prevent infanticide, which occurs often in the species. Nevertheless, field data indicates that males are still able to discern female reproductive condition through some unclear means (Ostner et al. 2006). Induced by the stress of having a new male in the group, pregnant females will sometimes abort (Rajpurohit & Srivastava 1994). As mentioned above, infanticide is common in gray langurs (Ostner et al. 2006).
For example, in one study, nearly a quarter of infants died through infanticide (Agoramoorthy 1993). It appears that infanticide serves a sexual selection function and allows greater potential for reproductive success in an incoming male after a male takeover of a group although there is some recent disagreement over this hypothesis (Ross 1993b; Rajpurohit et al. 2008). Infants are often protected against males which are attacking them by resident group adult males (Borries et al. 1999; Borries & Koenig 2000). Infanticidal males are usually recent immigrants to the group and only attack infants that are not their children (Borries & Koenig 2000).
Females usually solicit copulation and do so with solicitation behaviors such as head-shuddering, lowering the tail, and presenting the anogenital region (Sommer et al. 1992). Not all solicitations produce copulation however and even during copulation mating pairs are often harassed by other group members (Newton 1987). Further, not all sexual behavior is between opposite sexes, and in one study, around half of all sexual interactions of females were mounts with other females (Sommer et al. 2006).
In some areas reproduction is year-round with peaks during warmer periods of the year (Sommer et al. 1992). However, at other study sites, reproduction is seasonal and some authors suggest that year-round reproduction is only found in populations that are able to use human-related foods (Newton 1987). For example, in southern Nepal at Ramnagar, mating and estrus is restricted to July to October (births February to April) with females infertile outside of the mating season (Ziegler et al. 2000). Reproduction is also seasonal in central India, in the Maikal Hills, where reproduction occurs mostly between April and August (Newton 1987).
The average reproductive cycle of gray langurs at Jodhpur, India was 24.1 days, with a gestation length around 200 days (Winkler et al. 1984; Sommer et al. 1992). The age at first conception in females at this site is usually around 35 months of age although in some other populations this age is higher, and can be as high as around 6.7 years (Sommer et al. 1992; Borries et al. 2001; Rajpurohit 2004). The interbirth interval is 16.7 months (Sommer et al. 1992). However, because gray langurs are widespread, there is some variability between study sites (see literature review in Sommer et al. 1992).
PARENTAL CARE
Births are usually singletons, but twinning is known, and the majority of births occur at night (Winkler et al. 1989; Agoramoorthy 1992). At birth, infants have thin, dark brown or black hair. The skin is pale, but darkens to black by three months old (Sugiyama 1965). In one study, only around a third of infants survived into their third year (Winkler et al. 1984).
At birth, the infant clings to the mother’s chest and for most of the first week of life, the infant is found on the mother’s chest suckling or sleeping (Sugiyama 1965). In the first two weeks of the infant’s life, it will display little locomotor behavior but will become increasingly adept after that. Play behaviors also increase steadily after the first three weeks. Infant vocalizations include squeaks and shrieks, usually to communicate stress, and infants vocalize more in the first six weeks of life (Dolhinow & Murphy 1982). Quadrupedal locomotion is seen in an infant at around one month old, although only in the second month of age is locomotion skillful. By the second and third months of age they will walk, run and jump adeptly (Sugiyama 1965). At six weeks of age, the infant gray langur is eating foods on its own. By 9 to 12 months old, infants are near their mother only around 20% of the time (Dolhinow & Murphy 1982). Infant care is provided by other group females. Upon reaching two years of age, females will attempt to provide allocare to infants (Dolhinow & Krusko 1984). The infant is often transferred among group females, and may nurse on several of them, but in general, if a gray langur mother dies before an infant is 4 months old, the infant will generally die (Sugiyama 1965; Dolhinow & Murphy 1982). After six months old, locomotion is predominantly independent and carrying by the mother is rare (Sugiyama 1965).
Infants are sometimes kidnapped by females from neighboring groups but are sometimes retrieved by their mothers (Mohnot 1980).
Weaning starts at an average of 8.6 months old, and by 13 months of age, infants are completely weaned (Rajpurohit & Mohnot 1991). As adolescent gray langurs get closer to maturity, males become more peripheral in the group and are eventually pushed out, while females increasingly spend time cultivating social relationships and positioning themselves for entering the dominance hierarchy in their natal group (Nikolei & Borries 1997).
COMMUNICATION
Gray langurs have around 19 vocalization types including loud calls (also termed whoops), harsh barks, cough barks, grunt barks, pant barks, grunts, honks, rumbles, rumble screams, hiccups, and alarm calls (Bhaker et al. 2003; 2004). Loud calls (whoops) are only emitted by mature adult males and are often uttered in conjunction with displays (Hohmann 1989; Bhaker et al. 2004). Such calls are mostly heard in the morning, especially when leaving the sleeping site and during other changes in group activity. Langurs utilize an inflatable laryngeal sac during their emission (Hohmann 1989).
Harsh barks are also emitted by adult males, but subadult males also emit them and they are heard usually when surprised by a predator (Hohmann 1989; Bhaker et al. 2004). Cough barks are heard during group movement and are emitted by adult and subadult males. Grunt barks are heard during group movements and during agonistic interactions and are usually given by adult males, but also sometimes by other group members (Hohmann 1989; Bhaker et al. 2004). Rumble screams may also be heard in agonistic situations. Pant barks are heard in conjunction with loud calls and during inter-group interactions while grunts are heard during many different types of situations, but especially during agonism (Hohmann 1989; Bhaker et al. 2004). Adult males honk during inter-group interactions. During approaches, embraces, or mounts, rumbles are sometimes heard. Coughs pertain to many different types of situation and are uttered by most group demographics, excepting infants and adult males, and are usually heard and exchanged between more than one individual (Hohmann 1989; Bhaker et al. 2004). All group members emit hiccups, especially when a different group is sighted.
Finally, variable alarm calls are given by all demographics excepting small infants, in response to predators, surprises and other groups (Hohmann 1989; Bhaker et al. 2004). Gray langurs of varying ages may also use tonal contact calls, including isolation peeps (juveniles, infants, females), warbles (all but adult and subadult males), and squeals (mostly females) and shrieks (immature individuals) (Hohmann 1989). Wailing is heard from weaning infants, and the milk grumble is emitted by very young infants (Hohmann 1989). Adult males will grind their teeth in agonistic situations, while adult females will chatter their teeth during social grooming (Hohmann 1989).
Content last modified: October 28, 2008
Written by Kurt Gron.
Cite this page as:
Gron KJ. 2008 October 28. Primate Factsheets: Gray langur (Semnopithecus) Behavior . <http://pin.primate.wisc.edu/factsheets/entry/gray_langur/behav>. Accessed 2020 July 22.
INTERNATIONAL STATUS
For individual primate species conservation status, please search the IUCN Red List.
Also search the current scientific literature for primate conservation status (overall as well as for individual species), and visit CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora).
Conservation information last updated in 2008 follows, for comparison:
Gray langurs are protected by laws in India which forbid their killing and capture, alive or dead, although enforcement is a problem and most people do not even know that they are a protected species (Choudhhury 2001). While many populations are stable, a decline is seen in some areas (Srinivasulu & Nagulu 2001).
There are around 300,000 gray langurs in India (Mukherjee 2001). It is estimated that there are around 1000-1500 S. entellus in China and the species is considered endangered in the country (Wang et al. 1999; Zhang et al. 2002).
CONSERVATION THREATS
Threat: Human-Induced Habitat Loss and Degradation
In general, some of the biggest threats to natural forest habitats including gray langur habitats in India include logging, encroachment as well as plantation and slash-and-burn (jhum) agriculture (Choudhury 2001; Rao & Bhatnagar 2001). Other local activities which may threaten or degrade gray langur habitats include open cast mining, fire damage, grazing, ground litter removal, and non-timber forest products including wood for fuel, fodder, fruits, gums, seeds, and medicinal plants (Pirta et al. 1997; Rao & Bhatnagar 2001).
Threat: Harvesting (hunting/gathering)
Gray langurs are often kept as pets and are sometimes found for sale in markets. In fact, because of their role in the Hindu religion, it is generally not considered detrimental to keep or capture the animals. Indeed, they are sometimes kept for religious purposes by Hindu priests and for training for roadside performance (Ahmed 2001). Religious protections aside, some groups with different religious beliefs will hunt common langurs for food and for medicinal purposes (Ahmed 2001; Kumara & Singh 2004). Finally, various parts of gray langurs are sometimes kept as amulets with positive effects for the bearer and obviously, the death of the animal is a prerequisite for the procurement of such parts (Ahmed 2001). Gray langurs are also sometimes taken for biomedical research, and are sold for under $20 (Ahmed 2001).
Threat: Accidental Mortality
Gray langurs are often found around or on roads due in part to human provisioning, and also use roads for walking, playing, predator avoidance and foraging. As a result, even in protected areas, mortality due to automobile collisions can be high, accounting for as much as a quarter of total mortality, as is the case at the Kumbhalgarh Wildlife Sanctuary in Rajasthan, India (Chhangani 2004).
Threat: Persecution
In general, because gray langurs are considered sacred in many areas of India, they are generally not considered to be pests, a fact augmented by their generally less aggressive nature than other primates (Southwick & Siddiqi 2001). Still, gray langurs commonly crop-raid, and steal from homes which causes persecution by people (Chaudhuri et al. 2004). Attitudes are changing somewhat, partially due to an increase in the secularization of society and the animals are persecuted more than they have been in the past. Further, sometimes people will feed the animals around and in temples, but if they are found in their own houses, they will treat them as a nuisance (Manohar 1999). However, in urban habitats, gray langurs may steal and bite people to get food, reinforcing changes in attitudes and increasing persecution by humans. This may result in the deaths of gray langurs (Pirta 1982).
Threat: Natural Disasters
El Niño events can cause droughts which can severely affect gray langur populations. For example, as a result of such phenomena, two monsoons failed between 1999-2001 and natural-habitat langur populations suffered large reductions. However, urban-dwelling populations were able to weather such events with only minor population losses due to provisioning (Waite et al. 2007).
Threat: Changes in Native Species Dynamics
The destruction of large roosting trees by people has the effect of permitting easier access of predators to langurs, possibly increasing mortality due to predation (Pirta 1982).
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Content last modified: October 28, 2008
Written by Kurt Gron.
Cite this page as:
Gron KJ. 2008 October 28. Primate Factsheets: Gray langur (Semnopithecus) Conservation . <http://pin.primate.wisc.edu/factsheets/entry/gray_langur/cons>. Accessed 2020 July 22.
The following references were used in the writing of this factsheet. To find current references for Semnopithecus, search PrimateLit.
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Content last modified: October 28, 2008
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Semnopithecus entellus Photo: John Oates |
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Semnopithecus entellus Photo: Kamal Kumar Dua |
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Semnopithecus entellus Photo: Kamal Kumar Dua |
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Semnopithecus entellus Photo: Kamal Kumar Dua |
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Semnopithecus entellus Photo: Kamal Kumar Dua |
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Semnopithecus entellus Photo: Sarah Hrdy |
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Semnopithecus entellus Photo: Unknown |
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