Gray langur
Encyclopedia
Gray langurs or Hanuman langurs, the most widespread langurs of South Asia
, are a group of Old World monkey
s constituting the entirety of the genus
Semnopithecus. All taxa have traditionally been placed in the single species Semnopithecus entellus. In 2001, it was recommended that several distinctive former subspecies should be given full species status, so that seven species are recognized. A taxonomic classification with fewer species has also been proposed. Genetic
evidence suggests that the Nilgiri langur
and purple-faced langur
, which usually are placed in the genus Trachypithecus, actually belong in Semnopithecus.
Gray langurs are large and fairly 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 4000 metres (13,123.4 ft) in the Himalayas.
"Hanuman" refers to the Hindu deity Hanuman
.
.
Langurs mostly walk quadrupedally and spend half their time on and the ground and the other half in the trees. They will also make bipedal hops, climbing and descending supports with the body upright, and leaps. Langurs can leap 3.7-4.6 m (12.0-15.0 ft) horizontally and 10.7-12.2 m (35-40 ft) in descending.
. In 2001, it was proposed that seven species should be recognized, with the majority considered monotypic
. This was followed in Mammal Species of the World
in 2005, though several of the seven species intergrade, and alternative treatments exist where only two species (a northern and a southern) are recognized. Phylogenetic evidence supports at least three species (a north Indian, a south Indian and a Sri Lankan species). It has also been suggested that Semnopithecus priam
thersites is worthy of treatment as a species rather than a subspecies, but at present this is based on limited evidence.
It has been suggested that Trachypithecus should be considered only a subgenus of Semnopithecus. If maintaining the two as separate monophyletic genera, the purple-faced langur
and Nilgiri langur
belong in Semnopithecus instead of the usual 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.
The seven species of Semnopithecus recognized in Mammal Species of the World are:
in north India and the Nepal
ese, Bhutan
ese, and Tibet
an Himalayas
, east to Bangladesh
and west to Pakistan
’s Indus Valley. They possibly occur in Afghanistan.
Gray langurs can adapt to a variety of habitats. They inhabit arid
habitats such as desert areas, dry open scrub, dry deciduous
forests, but also tropical and subtropical evergreen rainforest
s, moist deciduous forest, broadleaf forest
, subtropical pine forest, riverine forest, open park woods, mountain foothills, mountain forests, Himalayan oak-coniferous forests, temperate coniferous forest, sub-alpine forest, grasslands, meadows, scrub, scrub forests, and mixed grasslands. They live at altitudes up to 4000 m (13,123.4 ft) including areas that receive snowfall in the winter. They can adapt well to human settlements, and are found in villages, towns, residential areas, tourist areas, temple grounds, orchards and cultivated areas. They live in densely populated cities like Jodhpur
, which has over a million inhabitants.
Ungulate
s like bovine and deer
will eat food dropped by foraging langurs. Langurs are preyed upon by leopards
, dhole
s and tigers
. Wolves, jackal
s and pythons may also prey on langurs.
s. However, unlike some other colobines they do not exclusively eat leaves and leaf buds of herbs, but also coniferous needles and cones, fruits and fruit buds, evergreen petioles
, shoots and roots, seeds, grass, bamboo
, fern
rhizomes, moss
es, and lichens. Leaves of trees and shrubs rank top of their preferred food, followed by herbs and grasses. Non-plant material consumed include spider webs, termite mounds and even cremated human remains. They forage on agricultural crops and other human foods, and even accept handouts. Although they occasionally drink, langurs get most of their water from the moisture in their food.
All-male groups tend to be the smallest of the groups and can consist of adults, sub-adults, and juveniles. There are some populations that have only multi-male groups as mixed sex groups while others have only uni-male groups as mixed sexed groups.
Some evidence suggests that multi-male groups are temporary and exist only in the transition period following a takeover during the mating season and soon split into uni-male and all-male groups.
Social hierarchies exist for all group types. In all-male groups, dominance is attained by displacing another member, chasing, fighting, copulatory success, and harassment. With sexually mature females, rank is based on physical condition and age. The youngest females rank highest and they drop in rank as they age. Aggressive and submissive interactions occur more often between high-ranking individuals in a group. Most changes in social rank in males are associated with emigration and immigration. An adult male may remain in a uni-male group for 45 months. The rate of male replacement can occur quickly or slowly depending on the group.
Females within a group are matrilineally related. Female memberships are also stable, but less so in larger groups. Relationships between the females tend to be friendly. They will eat, move and rest together and embrace, and greet each other. They will also groom amongst themselves with grooming directed both up and down the dominance hierarchy. However higher-ranking females give out and receive grooming more than lower ranking females. In addition, females groom males more than the other way around. Males and females in a group tend to be calm and cooperative. Relationships between males can range from peaceful and cooperative to antagonistic. While females remain in their natal groups, males will leave when they reach adulthood. Relationships between groups tend to be antagonistic. High-ranking males from different groups will display, vocalize, and fight among themselves.
Higher ranking females are more reproductively successful than lower ranking ones. They will mate both polygynously and polygamously.
Female grey langurs show no external sign that they are in a reproductive state. However, males seem to be able to deduce the reproduction state of female though some unknown means. Females will solicit copulation by shuddering the head, lowering the tail, and presenting the anogenital region. Solicitations are not always successful in achieving a copulation. When langurs mate, they are sometimes harassed by other group members. Females have even been recorded mounting other females.
The gestation period of grey langur lasts around 200 days, at least at Jodhpur, India. In some areas, reproduction is year-around. It appears that year-round reproduction occurs in populations that capitalize on human made foods. Other population have seasonal reproduction.
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. Infanticide is more commonly reported in uni-male groups, possibly because situations where one male breeds drive the evolution of this trait. In multi-male groups, the costs for infanticidal males are likely to be high as other resident males might defend the victim, and the benefits may be low due to the lower parental probability in multi-male groups. Nevertheless, infanticide does occur in these groups, and is suggested to be a male reproductive strategy intended to shorten the female’s interbirth interval and sire her next offspring.
Females usually give birth to a single infant, although twins do occur. Most births occur during the night. Infants are born with thin dark brown or black hair and pale skin. Infants spend their first week clinging to their mothers’ chest and suckling, or sleeping. They do not move much in terms of locomotion for the first two week of their life. As they approach their sixth week of life, infants vocalize more.
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 transferred among the group females. However if the mother dies, the infant usually follows. Langurs are weaned by 13 months.
and Kashmir gray langur
are considered threatened
. The latter is the rarest species of gray langur with less than 250 mature individuals remaining.
In India, langurs number at around 300,000. India has laws prohibiting the capturing or killing of langurs. Enforcement of these laws have proven to be difficult and it seems most people don’t know they are protected. The natural habitat of gray langurs is threatened by encroachment and plantation and slash-and-burn agriculture. Other threats 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.
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. Langurs are considered sacred in the Hindu religion and are sometimes kept for religious purposes by Hindu priests and for training for roadside performance. However there are some groups of different religions that will hunt langurs for medical purposes and parts of gray langurs are sometimes kept as amulets and seen as having positive effects for the bearer.
Because they are considered sacred and also due to their less aggressive behavior compared to other primates, langurs are generally not considered pests in many parts of India. Nevertheless, attitudes have somewhat changed partly due to secularization. Langurs will raid crops and steal food from houses and this causes people to persecute them. People will feed them in temples, but treat the ones they find at home as a nuisance. Langur stealing and biting people to get food in urban areas may also contribute to more persecutions.
South Asia
South Asia, also known as Southern Asia, is the southern region of the Asian continent, which comprises the sub-Himalayan countries and, for some authorities , also includes the adjoining countries to the west and the east...
, are a group of Old World monkey
Old World monkey
The Old World monkeys or Cercopithecidae are a group of primates, falling in the superfamily Cercopithecoidea in the clade Catarrhini. The Old World monkeys are native to Africa and Asia today, inhabiting a range of environments from tropical rain forest to savanna, shrubland and mountainous...
s constituting the entirety of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Semnopithecus. All taxa have traditionally been placed in the single species Semnopithecus entellus. In 2001, it was recommended that several distinctive former subspecies should be given full species status, so that seven species are recognized. A taxonomic classification with fewer species has also been proposed. Genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
evidence suggests that the Nilgiri langur
Nilgiri Langur
The Nilgiri langur is a lutung found in the Nilgiri Hills of the Western Ghats in South India. Its range also includes Kodagu in Karnataka,Kodayar Hills in Tamil Nadu and many other hilly areas in Kerala and Tamil nadu. This primate has glossy black fur on its body and golden brown fur on its head...
and purple-faced langur
Purple-faced Langur
The purple-faced langur , or purple-faced leaf monkey, is a species of Old World monkey endemic to Sri Lanka.This is a long-tailed arboreal species, mainly brown with a dark facemask and paler lower face...
, which usually are placed in the genus Trachypithecus, actually belong in Semnopithecus.
Gray langurs are large and fairly terrestrial
Terrestrial animal
Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...
, inhabiting forest, open lightly wooded habitats, and urban areas on the Indian subcontinent
Indian subcontinent
The Indian subcontinent, also Indian Subcontinent, Indo-Pak Subcontinent or South Asian Subcontinent is a region of the Asian continent on the Indian tectonic plate from the Hindu Kush or Hindu Koh, Himalayas and including the Kuen Lun and Karakoram ranges, forming a land mass which extends...
. Most species are found at low to moderate altitudes, but the Nepal gray langur
Nepal Gray Langur
Nepal gray langur is a gray langur endemic to the Himalayas in Nepal, far southwestern China, northern India, northern Pakistan, Bhutan and possibly Afghanistan...
and Kashmir gray langur
Kashmir Gray Langur
The Kashmir gray langur is an Old World monkey, one of the species of langurs. This, like other gray langurs, is a leaf-eating monkey. It is found in India west into Pakistani Kashmir and Nepal...
occur up to 4000 metres (13,123.4 ft) in the Himalayas.
"Hanuman" refers to the Hindu deity Hanuman
Hanuman
Hanuman , is a Hindu deity, who is an ardent devotee of Rama, a central character in the Indian epic Ramayana and one of the dearest devotees of lord Rama. A general among the vanaras, an ape-like race of forest-dwellers, Hanuman is an incarnation of the divine and a disciple of Lord Rama in the...
.
Characteristics
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. There are also significant variations in the size depending on the species, but the head-and-body length of males is typically up to 75 cm (29.5 in) and that of females is 65 cm (25.6 in). Their tail is always longer than their body. Langurs from the southern part of their range are smaller than those from the north. At 26.5 kg (58.4 lb), the heaviest langur ever recorded was a male Nepal gray langurNepal Gray Langur
Nepal gray langur is a gray langur endemic to the Himalayas in Nepal, far southwestern China, northern India, northern Pakistan, Bhutan and possibly Afghanistan...
.
Langurs mostly walk quadrupedally and spend half their time on and the ground and the other half in the trees. They will also make bipedal hops, climbing and descending supports with the body upright, and leaps. Langurs can leap 3.7-4.6 m (12.0-15.0 ft) horizontally and 10.7-12.2 m (35-40 ft) in descending.
Taxonomy
Traditionally, only Semnopithecus entellus was recognized as a species, the remainder all being treated as subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
. In 2001, it was proposed that seven species should be recognized, with the majority considered monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
. This was followed in Mammal Species of the World
Mammal Species of the World
Mammal Species of the World, now in its 3rd edition, is a standard reference work in zoology giving descriptions and bibliographic data for the known species of mammals.An updated Third Edition of Mammal Species of the World was published late in 2005:...
in 2005, though several of the seven species intergrade, and alternative treatments exist where only two species (a northern and a southern) are recognized. Phylogenetic evidence supports at least three species (a north Indian, a south Indian and a Sri Lankan species). It has also been suggested that Semnopithecus priam
Tufted Gray Langur
The tufted gray langur is an Old World monkey, one of the species of langurs. This, like other gray langurs, is a leaf-eating monkey. It is found in southeast India and Sri Lanka. It is one of several Semnopithecus species named after characters from The Iliad, along with Semnopithecus hector...
thersites is worthy of treatment as a species rather than a subspecies, but at present this is based on limited evidence.
It has been suggested that Trachypithecus should be considered only a subgenus of Semnopithecus. If maintaining the two as separate monophyletic genera, the purple-faced langur
Purple-faced Langur
The purple-faced langur , or purple-faced leaf monkey, is a species of Old World monkey endemic to Sri Lanka.This is a long-tailed arboreal species, mainly brown with a dark facemask and paler lower face...
and Nilgiri langur
Nilgiri Langur
The Nilgiri langur is a lutung found in the Nilgiri Hills of the Western Ghats in South India. Its range also includes Kodagu in Karnataka,Kodayar Hills in Tamil Nadu and many other hilly areas in Kerala and Tamil nadu. This primate has glossy black fur on its body and golden brown fur on its head...
belong in Semnopithecus instead of the usual Trachypithecus. At present it is unclear where the T. pileatus species group (consisting of the capped langur
Capped Langur
The capped langur is a species of primate in the Cercopithecidae family. It is found in Bangladesh, Nepal, Bhutan, China, India, and Myanmar. Its natural habitat is subtropical or tropical dry forests...
, Shortridge's langur
Shortridge's Langur
Shortridge's langur is a lutung native to Burma and China....
and Gee's golden langur
Gee's Golden Langur
Gee's golden langur , or simply the golden langur, is an Old World monkey found in a small region of western Assam, India and in the neighboring foothills of the Black Mountains of Bhutan. It is one of the most endangered primate species of India...
) belongs, as available mtDNA data place it in Semnopithecus, while Y chromosome
Y chromosome
The Y chromosome is one of the two sex-determining chromosomes in most mammals, including humans. In mammals, it contains the gene SRY, which triggers testis development if present. The human Y chromosome is composed of about 60 million base pairs...
data place it in Trachypithecus.
The seven species of Semnopithecus recognized in Mammal Species of the World are:
- Nepal gray langurNepal Gray LangurNepal gray langur is a gray langur endemic to the Himalayas in Nepal, far southwestern China, northern India, northern Pakistan, Bhutan and possibly Afghanistan...
Semnopithecus schistaceus - Kashmir gray langurKashmir Gray LangurThe Kashmir gray langur is an Old World monkey, one of the species of langurs. This, like other gray langurs, is a leaf-eating monkey. It is found in India west into Pakistani Kashmir and Nepal...
Semnopithecus ajax - Tarai gray langurTarai Gray LangurThe Tarai gray langur is an Old World monkey, and was formerly considered a subspecies of the northern plains gray langur...
Semnopithecus hector - Northern plains gray langurNorthern Plains Gray LangurThe northern plains gray langur is a species of primate in the Cercopithecidae family. It is found in India on the lowlands north of the Godavari and Krishna rivers and south of the Ganges. It is thought to be introduced to western Bangladesh by Hindu pilgrims on the bank of the Jalangi River...
Semnopithecus entellus - Black-footed gray langurBlack-footed Gray LangurThe black-footed gray langur is an Old World monkey, one of the species of langurs. This, like other gray langurs, is a leaf-eating monkey found in south India.-References:...
Semnopithecus hypoleucos - Southern plains gray langurSouthern Plains Gray LangurThe southern plains gray langur is a species of primate in the Cercopithecidae family. It is found in south west and west central India. Commonly known as Hanuman langur, this is the most widely found species of langur in India....
Semnopithecus dussumieri - Tufted gray langurTufted Gray LangurThe tufted gray langur is an Old World monkey, one of the species of langurs. This, like other gray langurs, is a leaf-eating monkey. It is found in southeast India and Sri Lanka. It is one of several Semnopithecus species named after characters from The Iliad, along with Semnopithecus hector...
Semnopithecus priam
Distribution and habitat
They range from KashmirKashmir
Kashmir is the northwestern region of the Indian subcontinent. Until the mid-19th century, the term Kashmir geographically denoted only the valley between the Great Himalayas and the Pir Panjal mountain range...
in north India and the Nepal
Nepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...
ese, Bhutan
Bhutan
Bhutan , officially the Kingdom of Bhutan, is a landlocked state in South Asia, located at the eastern end of the Himalayas and bordered to the south, east and west by the Republic of India and to the north by the People's Republic of China...
ese, and Tibet
Tibet
Tibet is a plateau region in Asia, north-east of the Himalayas. It is the traditional homeland of the Tibetan people as well as some other ethnic groups such as Monpas, Qiang, and Lhobas, and is now also inhabited by considerable numbers of Han and Hui people...
an Himalayas
Himalayas
The Himalaya Range or Himalaya Mountains Sanskrit: Devanagari: हिमालय, literally "abode of snow"), usually called the Himalayas or Himalaya for short, is a mountain range in Asia, separating the Indian subcontinent from the Tibetan Plateau...
, east to Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...
and west to Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...
’s Indus Valley. They possibly occur in Afghanistan.
Gray langurs can adapt to a variety of habitats. They inhabit arid
Arid
A region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life...
habitats such as desert areas, dry open scrub, dry deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
forests, but also tropical and subtropical evergreen rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...
s, moist deciduous forest, broadleaf forest
Broadleaf forest
Broadleaf forest can refer to:* Temperate broadleaf and mixed forests* Tropical and subtropical dry broadleaf forests* Tropical and subtropical moist broadleaf forests...
, subtropical pine forest, riverine forest, open park woods, mountain foothills, mountain forests, Himalayan oak-coniferous forests, temperate coniferous forest, sub-alpine forest, grasslands, meadows, scrub, scrub forests, and mixed grasslands. They live at altitudes up to 4000 m (13,123.4 ft) including areas that receive snowfall in the winter. They can adapt well to human settlements, and are found in villages, towns, residential areas, tourist areas, temple grounds, orchards and cultivated areas. They live in densely populated cities like Jodhpur
Jodhpur
Jodhpur , is the second largest city in the Indian state of Rajasthan. It is located west from the state capital, Jaipur and from the city of Ajmer. It was formerly the seat of a princely state of the same name, the capital of the kingdom known as Marwar...
, which has over a million inhabitants.
Ecology and behavior
Gray langurs are diurnal. They sleep during the night in trees or hunting towers or high-tension electric poles when in human settlements. When resting in trees, they generally prefer the highest branches.Ungulate
Ungulate
Ungulates are several groups of mammals, most of which use the tips of their toes, usually hoofed, to sustain their whole body weight while moving. They make up several orders of mammals, of which six to eight survive...
s like bovine and deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
will eat food dropped by foraging langurs. Langurs are preyed upon by leopards
Indian leopard
The Indian leopard is a leopard subspecies widely distributed on the Indian subcontinent. It is one of the five big cats found in India, apart from Asiatic lion, Bengal tiger, snow leopard and clouded leopard....
, dhole
Dhole
The dhole is a species of canid native to South and Southeast Asia. It is the only extant member of the genus Cuon, which differs from Canis by the reduced number of molars and greater number of teats...
s and tigers
Bengal Tiger
The Bengal tiger is a tiger subspecies native to the Indian subcontinent that in 2010 has been classified as endangered by IUCN...
. Wolves, jackal
Jackal
Although the word jackal has been historically used to refer to many small- to medium-sized species of the wolf genus of mammals, Canis, today it most properly and commonly refers to three species: the black-backed jackal and the side-striped jackal of sub-Saharan Africa, and the golden jackal of...
s and pythons may also prey on langurs.
Diet
Gray langurs are primarily herbivoreHerbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s. However, unlike some other colobines they do not exclusively eat leaves and leaf buds of herbs, but also coniferous needles and cones, fruits and fruit buds, evergreen petioles
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
, shoots and roots, seeds, grass, bamboo
Bamboo
Bamboo is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family....
, fern
Fern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...
rhizomes, moss
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
es, and lichens. Leaves of trees and shrubs rank top of their preferred food, followed by herbs and grasses. Non-plant material consumed include spider webs, termite mounds and even cremated human remains. They forage on agricultural crops and other human foods, and even accept handouts. Although they occasionally drink, langurs get most of their water from the moisture in their food.
Social structure
Gray langurs exist in three types of groups:- uni-male groups, comprising one adult male, several females and offspring;
- multi-male groups, comprising males and females of all ages;
- all male groups.
All-male groups tend to be the smallest of the groups and can consist of adults, sub-adults, and juveniles. There are some populations that have only multi-male groups as mixed sex groups while others have only uni-male groups as mixed sexed groups.
Some evidence suggests that multi-male groups are temporary and exist only in the transition period following a takeover during the mating season and soon split into uni-male and all-male groups.
Social hierarchies exist for all group types. In all-male groups, dominance is attained by displacing another member, chasing, fighting, copulatory success, and harassment. With sexually mature females, rank is based on physical condition and age. The youngest females rank highest and they drop in rank as they age. Aggressive and submissive interactions occur more often between high-ranking individuals in a group. Most changes in social rank in males are associated with emigration and immigration. An adult male may remain in a uni-male group for 45 months. The rate of male replacement can occur quickly or slowly depending on the group.
Females within a group are matrilineally related. Female memberships are also stable, but less so in larger groups. Relationships between the females tend to be friendly. They will eat, move and rest together and embrace, and greet each other. They will also groom amongst themselves with grooming directed both up and down the dominance hierarchy. However higher-ranking females give out and receive grooming more than lower ranking females. In addition, females groom males more than the other way around. Males and females in a group tend to be calm and cooperative. Relationships between males can range from peaceful and cooperative to antagonistic. While females remain in their natal groups, males will leave when they reach adulthood. Relationships between groups tend to be antagonistic. High-ranking males from different groups will display, vocalize, and fight among themselves.
Reproduction and parenting
In uni-male groups, the resident male is usually the sole breeder of the females and sires all the young. In multi-male groups, the highest ranking male fathers most of the offspring followed by the next ranking males and even outside males will father young.Higher ranking females are more reproductively successful than lower ranking ones. They will mate both polygynously and polygamously.
Female grey langurs show no external sign that they are in a reproductive state. However, males seem to be able to deduce the reproduction state of female though some unknown means. Females will solicit copulation by shuddering the head, lowering the tail, and presenting the anogenital region. Solicitations are not always successful in achieving a copulation. When langurs mate, they are sometimes harassed by other group members. Females have even been recorded mounting other females.
The gestation period of grey langur lasts around 200 days, at least at Jodhpur, India. In some areas, reproduction is year-around. It appears that year-round reproduction occurs in populations that capitalize on human made foods. Other population have seasonal reproduction.
Infanticide
Infanticide (zoology)
In animals, infanticide involves the killing of young offspring by a mature animal of its own species, and is studied in zoology, specifically in the field of ethology. Ovicide is the analogous destruction of eggs. Although human infanticide has been widely studied, the practice has been observed...
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. Infanticide is more commonly reported in uni-male groups, possibly because situations where one male breeds drive the evolution of this trait. In multi-male groups, the costs for infanticidal males are likely to be high as other resident males might defend the victim, and the benefits may be low due to the lower parental probability in multi-male groups. Nevertheless, infanticide does occur in these groups, and is suggested to be a male reproductive strategy intended to shorten the female’s interbirth interval and sire her next offspring.
Females usually give birth to a single infant, although twins do occur. Most births occur during the night. Infants are born with thin dark brown or black hair and pale skin. Infants spend their first week clinging to their mothers’ chest and suckling, or sleeping. They do not move much in terms of locomotion for the first two week of their life. As they approach their sixth week of life, infants vocalize more.
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
Alloparenting
In biology and sociology, alloparenting is where individuals other than the actual parents act in a parental role.One common form of alloparenting is where grandparents adopt a parental role. This is sometimes named a "skipped generation household"...
occurs among langurs, starting when the infants reach two years of age. The infant will be transferred among the group females. However if the mother dies, the infant usually follows. Langurs are weaned by 13 months.
Vocalizations
Gray langurs are recorded to make a number of vocalizations.- lough calls or whoops made only by adult male during displays;
- harsh barks made by adult and subadult males when surprised by a predator;
- cough barks made by adult and subadult 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 in conjunction with loud calls during inter-group interactions;
- grunts made in many different situations, usually in agonistic ones;
- honks made by adult males during inter-group interactions;
- rumbles made during approaches, embraces, and mounts;
- hiccups made by most members of a group when another group is sighted.
Status and conservation
While many populations of gray langurs are stable, in some areas they are declining, and both the black-footed gray langurBlack-footed Gray Langur
The black-footed gray langur is an Old World monkey, one of the species of langurs. This, like other gray langurs, is a leaf-eating monkey found in south India.-References:...
and Kashmir gray langur
Kashmir Gray Langur
The Kashmir gray langur is an Old World monkey, one of the species of langurs. This, like other gray langurs, is a leaf-eating monkey. It is found in India west into Pakistani Kashmir and Nepal...
are considered threatened
Threatened species
Threatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...
. The latter is the rarest species of gray langur with less than 250 mature individuals remaining.
In India, langurs number at around 300,000. India has laws prohibiting the capturing or killing of langurs. Enforcement of these laws have proven to be difficult and it seems most people don’t know they are protected. The natural habitat of gray langurs is threatened by encroachment and plantation and slash-and-burn agriculture. Other threats 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.
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. Langurs are considered sacred in the Hindu religion and are sometimes kept for religious purposes by Hindu priests and for training for roadside performance. However there are some groups of different religions that will hunt langurs for medical purposes and parts of gray langurs are sometimes kept as amulets and seen as having positive effects for the bearer.
Because they are considered sacred and also due to their less aggressive behavior compared to other primates, langurs are generally not considered pests in many parts of India. Nevertheless, attitudes have somewhat changed partly due to secularization. Langurs will raid crops and steal food from houses and this causes people to persecute them. People will feed them in temples, but treat the ones they find at home as a nuisance. Langur stealing and biting people to get food in urban areas may also contribute to more persecutions.