Template:Short description Template:Automatic taxobox
Semnopithecus is a genus of Old World monkeys native to the Indian subcontinent, with all species with the exception of two being commonly known as gray langurs.<ref name=msw3>Template:MSW3 Groves</ref> Traditionally only the species Semnopithecus entellus was recognized, but since about 2001 additional species have been recognized. The taxonomy has been in flux, but currently eight species are recognized.
Members of the genus Semnopithecus are terrestrial, inhabiting forest, open lightly wooded habitats, and urban areas on the Indian subcontinent. Most species are found at low to moderate altitudes, but the Nepal gray langur and Kashmir gray langur occur up to Template:Convert in the Himalayas.<ref name="IUCNNepalgraylangur"/><ref name="IUCNKashmirgraylangur"/>
CharacteristicsEdit
These langurs are largely gray (some more yellowish), with a black face and ears. Externally, the various species mainly differ in the darkness of the hands and feet, the overall color and the presence or absence of a crest.<ref name=Groves2001>Template:Cite book</ref><ref name=Brandon-Jones>Template:Cite journal</ref> Typically all north Indian gray langurs have their tail tips looping towards their head during a casual walk whereas all south Indian and Sri Lankan gray langurs have an inverted "U" shape or a "S" tail carriage pattern.<ref>Template:Cite journal</ref> There are also significant variations in the size depending on the sex, with the male always larger than the female. The head-and-body length is from Template:Convert. Their tails, at Template:Convert are always longer than their bodies.<ref name="Burnie"/> Langurs from the southern part of their range are smaller than those from the north. At Template:Convert, the heaviest langur ever recorded was a male Nepal gray langur.<ref name=Brandon-Jones/> The larger gray langurs are rivals for the largest species of monkey found in Asia. The average weight of gray langurs is Template:Convert in the males and Template:Convert in the females.<ref name="Burnie"/>
Langurs mostly walk quadrupedally and spend half of their time on the ground and the other half in trees. They will also make bipedal hops, climbing and descending supports with the body upright, and leaps. Langurs can leap Template:Convert horizontally and Template:Convert in descending.<ref name="Ripley 1967"/>
TaxonomyEdit
Traditionally, only Semnopithecus entellus was recognized as a species, the remainder all being treated as subspecies. In 2001, it was proposed that seven species should be recognized.<ref name=Groves2001/> This was followed in Mammal Species of the World in 2005,<ref name=msw3/> though several of the seven species intergrade, and alternative treatments exist where only two species (a northern and a southern) are recognized.<ref name=Brandon-Jones/> Phylogenetic evidence supports at least three species: a north Indian, a south Indian and a Sri Lankan one.<ref name=Phylogenetic>Template:Cite journal</ref><ref name=molecular>Template:Cite journal</ref>
It has been suggested that the Semnopithecus priam thersites is worthy of treatment as a species rather than a subspecies, but at present this is based on limited evidence.<ref>Template:Cite iucn</ref> During a study based on external morphology and ecological niche modelling in Peninsular India six main types were found, but continued to label all as subspecies. Coat color is highly variable, possible due to phenotypic plasticity and therefore of questionable value in species delimitation.<ref name=Nag>Template:Cite journal</ref><ref>Template:Cite journal</ref>
It has been suggested that Trachypithecus should be considered only a subgenus of Semnopithecus.<ref name=Brandon-Jones/> If maintaining the two as separate monophyletic genera, the purple-faced langur and Nilgiri langur belong in Semnopithecus instead of their former genus Trachypithecus. At present it is unclear where the T. pileatus species group (consisting of the capped langur, Shortridge's langur and Gee's golden langur) belongs, as available mtDNA data place it in Semnopithecus, while Y chromosome data place it in Trachypithecus.<ref name=Phylogenetic/> A possible explanation for this is that the T. pileatus species group is the result of fairly recent hybridization between Semnopithecus and Trachypithecus.<ref name=molecular/>
As of 2005, the authors of Mammal Species of the World recognized the following seven Semnopithecus species<ref name=msw3/>
- Nepal gray langur Semnopithecus schistaceus
- Kashmir gray langur Semnopithecus ajax
- Tarai gray langur Semnopithecus hector
- Northern plains gray langur Semnopithecus entellus
- Black-footed gray langur Semnopithecus hypoleucos
- Southern plains gray langur Semnopithecus dussumieri
- Tufted gray langur Semnopithecus priam
Results of analysis of mitochondrial cytochrome b gene and two nuclear DNA-encoded genes of several colobine species revealed that Nilgiri and purple-faced langurs cluster with gray langur, while Trachypithecus species form a distinct clade.<ref>Template:Cite journal</ref> Since then, two other species have been moved from Trachypithecus to Semnopithecus:<ref name=handbook>Template:Cite book</ref><ref name=asian>Template:Cite journal</ref>
- Purple-faced langur Semnopithecus vetulus
- Nilgiri langur Semnopithecus johnii
In addition, Semnopithecus dussumieri has been determined to be invalid.<ref name=Nag/><ref name=asian/><ref name=mdd>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=itis>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Most of the range that had been considered S. dussumieri is now considered S. entellus.<ref name=handbook/><ref name=asian/>
Thus the current generally accepted species within the genus Semnopithecus are:<ref name=asian/><ref name=mdd/><ref name=itis/> Template:Species table Template:Species table/row Template:Species table/row Template:Species table/row Template:Species table/row Template:Species table/row Template:Species table/row Template:Species table/row Template:Species table/row Template:Species table/end
A 2013 genetic study indicated that while S. entellus, S. hypoleucos, S. priam and S. johnii are all valid taxa, there has been hybridization between S. priam and S. johnii.<ref name=genet>Template:Cite journal</ref> It also indicated that there has been some hybridization between S. entellus and S. hypoleucos where their ranges overlap, and a small amount of hybridization between S. hypoleucos and S. priam.<ref name=genet/> It also suggested that S. priam and S. johnii diverged from each other fairly recently.<ref name=genet/>
Distribution and habitatEdit
The entire distribution of all gray langur species stretches from the Himalayas in the north to Sri Lanka in the south, and from Bangladesh in the east to Pakistan in the west.<ref>Roonwal, M.L., Mohnot, S.M. (1977) Primates of South Asia: ecology, sociobiology, and behavior. Harvard University Press, Cambridge (MA)</ref> They possibly occur in Afghanistan.<ref name=Brandon-Jones/> The bulk of the gray langur distribution is within India, and all seven currently recognized species have at least a part of their range in this country.<ref name=Groves2001/>
Gray langurs can adapt to a variety of habitats.<ref name= "Oppenheimer 1977"/> They inhabit arid habitats like deserts, tropical habitats like tropical rainforests and temperate habitats like coniferous forests, deciduous habitats and mountains habitats. They are found at sea level to altitudes up to Template:Convert.<ref name="IUCNNepalgraylangur"/><ref name="IUCNKashmirgraylangur"/> They can adapt well to human settlements, and are found in villages, towns and areas with housing or agriculture.<ref name= "Bennett 1994"/> They live in densely populated cities like Jodhpur, which has a population numbering up to a million.<ref name=r2/>
Ecology and behaviorEdit
Gray langurs are diurnal. They sleep during the night in trees but also on man-made structures like towers and electric poles when in human settlements.<ref name=r3/> When resting in trees, they generally prefer the highest branches.<ref name=r4/>
Ungulates like bovine and deer will eat food dropped by foraging langurs.<ref name=r5/> Langurs are preyed upon by leopards, dholes and tigers.<ref>Template:Cite thesis</ref> Wolves, jackals, Asian black bears and pythons may also prey on langurs.
DietEdit
Gray langurs are primarily herbivores. However, unlike some other colobines they do not depend on leaves and leaf buds of herbs, but will also eat coniferous needles and cones, fruits and fruit buds, evergreen petioles, shoots and roots, seeds, grass, bamboo, fern rhizomes, mosses, and lichens. Leaves of trees and shrubs rank at the top of preferred food, followed by herbs and grasses. Non-plant material consumed include spider webs, termite mounds and insect larvae.<ref>Template:Cite journal</ref> They forage on agricultural crops and other human foods, and even accept handouts.<ref name="Vogel 1977" /> Although they occasionally drink, langurs get most of their water from the moisture in their food.<ref name="r6" />
Social structureEdit
Gray langurs exist in three types of groups:
- one-male groups, comprising one adult male, several females and offspring;
- multiple-male groups, comprising males and females of all ages;
- all-male groups.<ref name="Rajpurohit 1992"/><ref name="Newton 1994"/>
All-male groups tend to be the smallest of the groups and can consist of adults, subadults, and juveniles. Some populations have only multiple-male groups as mixed sex groups, while others have only one-male groups as mixed sexed groups.<ref name="Rajpurohit 1992"/>
Some evidence suggests multiple-male groups are temporary and exist only after a takeover, and subsequently split into one-male and all-male groups.<ref name=r7/>
Social hierarchies exist for all group types.<ref name="Srivastava 1992"/><ref name="Rajpurohit 2005"/> In all-male groups, dominance is attained through aggression and mating success.<ref name="Rajpurohit 2008"/> With sexually mature females, rank is based on physical condition and age.<ref name="Koenig 2000"/><ref name="Borries 1991"/> The younger the female, the higher the rank. Dominance rituals are most common among high-ranking langurs.<ref name="Rajpurohit 2005"/> Most changes in social rank in males take place during changes in group members. An adult male may remain in a one-male group for 45 months.<ref name="Newton 1987"/> The rate of male replacement can occur quickly or slowly depending on the group.<ref name=r8/>
Females within a group are matrilineally related. Female memberships are also stable, but less so in larger groups.<ref name="Newton 1994"/><ref name="Koenig 2000"/> Relationships between the females tend to be friendly. They will do various activities with each together, such as foraging, traveling and resting. They will also groom each other regardless of their rank. However, higher-ranking females give out and receive grooming the most.<ref name=r9/> In addition, females groom males more often than the other way around.<ref name=r10/> Male and female relationships are usually positive. Relationships between males can range from peaceful to violent. While females remain in their natal groups, males will leave when they reach adulthood.<ref name="Newton 1994"/> Relationships between groups tend to be hostile. High-ranking males from different groups will display, vocalize, and fight among themselves.
Reproduction and parentingEdit
In one-male groups, the resident male is usually the sole breeder of the females and sires all the young. In multiple-male groups, the highest-ranking male fathers most of the offspring, followed by the next-ranking males and even outside males will father young.<ref name=r11/> Higher-ranking females are more reproductively successful than lower-ranking ones.<ref name="Borries 1991"/>
Female gray langurs do not make it obvious that they are in estrous. However, males are still somehow able to deduce the reproduction state of females.<ref name=r12/> Females signal that they are ready to mate by shuddering the head, lowering the tail, and presenting their anogenital regions.<ref name="Sommer 1992"/> Such solicitations do not always lead to copulation. When langurs mate, they are sometimes disrupted by other group members.<ref name="Newton 1987"/> Female langurs have been recorded mounting other females.<ref name=b1/>
The gestation period of gray langur lasts around 200 days, at least at Jodhpur, India. In some areas, reproduction is year-around.<ref name="Sommer 1992"/> Year-round reproduction appears to occur in populations that capitalize on human-made foods. Other populations have seasonal reproduction.<ref name="Newton 1987"/> Infanticide is common among gray langurs. Most infanticidal langurs are males that have recently immigrated to a group and driven out the prior male. These males only kill infants that are not their own.<ref name=b2/> Infanticide is more commonly reported in one-male groups, perhaps because one male monopolizing matings drives the evolution of this trait. In multiple-male groups, the costs for infanticidal males are likely to be high as the other males may protect the infants and they can't ensure that they'll sire young with other males around. Nevertheless, infanticide does occur in these groups, and is suggested that such practices serve to return a female to estrous and gain the opportunity to mate.<ref name="Borries 1997"/>
Females usually give birth to a single infant, although twins do occur. Most births occur during the night.<ref name="Agoramoorthy 1992"/> Infants are born with thin, dark brown or black hair and pale skin. Infants spend their first week attached to their mothers' chests and mostly just suckle or sleep.<ref name="Sugiyama 1965"/> They do not move much in terms of locomotion for the first two weeks of their life. As they approach their sixth week of life, infants vocalize more.<ref name=r13/> They use squeaks and shrieks to communicate stress. In the following months, the infants are capable of quadrupedal locomotion and can walk, run and jump by the second and third months. Alloparenting occurs among langurs, starting when the infants reach two years of age. The infant will be given to the other females of the group. However, if the mother dies, the infant usually follows.<ref name="Sugiyama 1965"/> Langurs are weaned by 13 months.
VocalizationsEdit
Gray langurs are recorded to make a number of vocalizations:<ref name="Bhaker 2004"/><ref name="Hohmann 1989"/>
- loud calls or whoops made only by adult males during displays;
- harsh barks made by adult and subadult males when surprised by a predator;
- cough barks made by adults and subadults during group movements;
- grunt barks made mostly by adult males during group movements and agonistic interactions;
- rumble screams made in agonistic interactions;
- pant barks made with loud calls when groups are interacting;
- grunts made in many different situations, usually in agonistic ones;
- honks made by adult males when groups are interacting;
- rumbles made during approaches, embraces, and mounts;
- hiccups made by most members of a group when they find another group.
Status and conservationEdit
Gray langurs have stable populations in some areas and declining ones in others.<ref name=r14/> Both the black-footed gray langur and Kashmir gray langur are considered threatened.<ref name="IUCNKashmirgraylangur"/><ref name="IUCNBlack-footedgraylangur"/> The latter is the rarest species of gray langur, with less than 250 mature individuals remaining.<ref name="IUCNKashmirgraylangur"/>
In India, gray langurs number at around 300,000.<ref name=r15/> India has laws prohibiting the capturing or killing of langurs, but they are still hunted in some parts of the country.<ref name=Nag/> Enforcement of these laws has proven to be difficult and it seems most people are unaware of their protection.<ref name= "Choudhury 2001"/> Populations are also threatened by mining, forest fires and deforestation for wood.<ref name=r16/>
Langurs can be found near roads and can become victims of automobile accidents. This happens even in protected areas, with deaths by automobile collisions making nearly a quarter of mortality in Kumbhalgarh Wildlife Sanctuary in Rajasthan, India.<ref name=r17/> Langurs are considered sacred in the Hindu religion and are sometimes kept for religious purposes by Hindu priests and for roadside performances. However, some religious groups use langurs as food and medicine, and parts of gray langurs are sometimes kept as amulets for good luck.<ref name= "Ahmed 2001"/>
Because of their sacred status and their less aggressive behavior compared to other primates, langurs are generally not considered pests in many parts of India. Despite this, research in some areas show high levels of support for the removal of langurs from villages, their sacred status no longer important.<ref name=r18/> Langurs will raid crops and steal food from houses, and this causes people to persecute them.<ref name=r18/> While people may feed them in temples, they do not extend such care to monkeys at their homes.<ref name=b3/> Langurs stealing and biting people to get food in urban areas may also contribute to more persecutions.<ref name=r19/>
ReferencesEdit
SourcesEdit
External linksEdit
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