Gray langur

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.

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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

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).

LINKS TO MORE ABOUT CONSERVATION

CONSERVATION INFORMATION

• No current links for Semnopithecus
• Links for all species

CONSERVATION NEWS

• Sri Lanka hopes wildlife glories will attract new tourists  (AFP; September 18, 2008)
• Links for all species

ORGANIZATIONS INVOLVED IN Semnopithecus CONSERVATION

• Animal Sanctuary of the United States-Wild Animal Orphanage

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.

REFERENCES

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	Semnopithecus entellus Photo: John Oates
	Semnopithecus entellus Photo: Kamal Kumar Dua
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	Semnopithecus entellus Photo: Kamal Kumar Dua
	Semnopithecus entellus Photo: Kamal Kumar Dua
	Semnopithecus entellus Photo: Sarah Hrdy
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