Purple-faced langur

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Purple-faced langur
Purple-faced langur (Semnopithecus vetulus vetulus).jpg
Semnopithecus vetulus vetulus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Family: Cercopithecidae
Genus: Semnopithecus
Species:
S. vetulus [2]
Binomial name
Semnopithecus vetulus [2]
(Erxleben, 1777)
Purple-faced Langur area.png
Purple-faced langur range
Synonyms

Trachypithecus vetulus

The purple-faced langur (Semnopithecus vetulus), [2] also known as the purple-faced leaf monkey, is a species of Old World monkey that is endemic to Sri Lanka. The animal is a long-tailed arboreal species, identified by a mostly brown appearance, dark face (with paler lower face) and a very shy nature. The species was once highly prevalent, found in suburban Colombo and the "wet zone" villages (areas with high temperatures and high humidity throughout the year, whilst rain deluges occur during the monsoon seasons), [3] but rapid urbanization has led to a significant decrease in the population level of the monkeys. [4] It had traditionally been classified within the genus Trachypithecus but was moved to the genus Semnopithecus based on DNA evidence indicating that is it more closely related to the gray langurs.

Contents

In Sinhala, it is known as ශ්‍රී ලංකා කළු වඳුරා [kʌlu vʌⁿðura] (Sri Lanka black monkey).

Description

In the purple-faced langur, males are usually larger than females. Males measure 50 to 67.1 cm (19.7 to 26.4 in) in head-body length with a tail of 67 to 85.1 cm (26.4 to 33.5 in). Females possess a head-body length 44.7 to 60 cm (17.6 to 23.6 in) and tail length of 58.9 to 82 cm (23.2 to 32.3 in). [5] [6] The pelage may generally vary from blackish to grayish. The species tends to have whitish to gray short 'trousers' rounded off by purplish-black faces with white sideburns. Part of the back is covered with whitish fur, and tail is also furred with black and white mixed colors. The feet and hands are also purplish-black in color. Size varies among the subspecies. Typically adults will weigh somewhere between 3.1 and 11.4 kg (6.8 and 25.1 lb), averaging about 7.08 kg (15.6 lb). [7] [8] The smallest subspecies (S. v. nestor) commonly weighs between 3.8 and 6 kg (8.4 and 13.2 lb). [9] Average weight from other subspecies has been recorded up to 7.8 kg (17 lb) in females and 8.5 kg (19 lb) in males with some exceptionally big langurs weighing up to perhaps 18 kg (40 lb). [10] Among the primates that live in Sri Lanka, it is somewhat smaller than the tufted gray langur despite leading males of the group of purple-faced langurs often being larger than the tufted gray langur that lived together in the habitats. In the subspecies known as the "bear monkey" (S. v. monitcola) usually has a darker coat and usually sports a heavy mustache. In this species, the hair of crown directed backwards throughout, not radiating. it lacks the crest of tufted gray langurs and has hair on the crown no longer than on temples and nape. Purple-faced langurs have a rump that is pure white or whitish gray.

Subspecies

According to the Mammals of Sri Lanka, the 4 subspecies are recognized as follows. [11]

All four recognizable subspecies exhibit different cranial and pelage characteristics, as well as body size. The western purple-faced langur is one of the 25 most endangered primates in the world. [12] Most groups of langurs contain only one adult male. [13] [14]

A possible subspecies called Semnopithecus vetulus harti is recognized, but not yet given validity. This subspecies is known from some skins found from Jaffna peninsula and north of the Vavuniya. Uniquely, this subspecies has yellowish golden hair on its scalp and a golden sheen to its fur. Other than these differences, anatomy and all the other aspects are similar to the Semnopithecus vetulus philbricki. [15]

Although traditionally classified within the genus Trachypithecus based on morphological similarities, DNA and vocal evidence suggests that the purple-faced langur actually is more closely related to the gray langurs of the genus Semnopithecus. [16] [17] [18] [19] [20] [21]

Habitat and status

The purple-faced langur is found in closed canopy forests in Sri Lanka's mountains and the southwestern part of the country, known as the "wet zone". Only 19% of Sri Lanka consists of forested areas. This habitat has decreased from 80% in 1980 to ~25% in 2001. [12] Currently, this range has decreased to below 3%. The range consists of the most densely populated lowland rainforest areas of Sri Lanka. Deforestation has resulted in the langurs home ranges to be exposed to direct sunlight. Purple-faced langurs are most often found in small and widely scattered groups. Ninety percent of the langurs range, now consists of human populated areas. Populations are critically low within and between sites. Threats to this species include infringement on range by croplands, grazing, changing agriculture, road production, soil loss/erosion and deforestation, poisoning from prevention of crop raiding, and hunting for medicine and food. [13] [14]

Its range has constricted greatly in the face of human encroachment, although it can still be seen in Sinharaja, Kitulgala, Kandalama, Mihintale, in the mountains at Horton Plains National Park or in the rainforest near the city of Galle.

Behaviour and ecology

Diet

The purple-faced langur is mostly folivorous, but will also feed on fruits, flowers, and seeds. While they normally avoid human habitations, fruit such as jak ( Artocarpus heterophyllus ), rambutan ( Nephelium lappaceum ), banana ( Musa balbisiana ), and mango ( Mangifera indica ) may contribute up to 50% to their diet in cultivated areas. [12] In the wild, food such as the fruits of Dimocarpus longan and Drypetes sepiaria are taken. Purple-faced langur digestion is adapted to derive the majority of required nutrients and energy from complex carbohydrates found in leaves, with the help of specialized stomach bacteria. [22] Where the species' diet is currently heavily dependent cultivated fruits, the ability to derive sufficient nutrition may become impaired. [12] Seasonal availability of fruit may serve to increase this effect. [23]

Semnopithecus vetulus feed on a less diverse diet than S. priam, with a greater proportion of leaves. Food plants that have been identified include Holoptelea integrifolia , Hydnocarpus venenata , Macaranga peltata , Manilkara hexandra , Mikania scandens , Mischodon zeylanica , Pterospermum suberifolium , Tetrameles nudiflora , Vitex altissima , and Wrightia angustifolia . [24] The purple-faced langur was found to be dominated by tufted gray langurs in mixed feeding groups. [7]

Communication

Loud calls are often used to distinguish between individual purple-faced langurs. The elements of a call fall into three categories: harsh barks, whoops, and residuals. Individuals can be differentiated by the number of phrases and residuals within a call. Calls occur more often in the morning mostly stimulated by neighboring groups and territorial battles. More calls occur during sunny periods than cloudy. The fewest calls occur in the evening. Daytime calls usually aid in the defense of home ranges. The loud barking call, particularly of the highland form, can be mistaken for the roar of a predator such as a leopard. Calls of the purple-faced langur differ from those of any of the subspecies. Environmental characters impact call times as well as anthropogenic disturbance. Vocalization can be used to alert members of predators, attract mates, defend territory, and locate group members. Vocalization is extremely important for the use in conservation especially because they are very difficult to observe directly. Adult males are the most vocal among the entire group. Defensive whooping calls are also accompanied by intense visual and locomotive displays. Vocalizations are also helpful in determining taxonomic identification. [14] Based on alarm calls issued in response to these and known predators of the similar tufted gray langur, the main potential predators of this species are likely to be leopards followed infrequently perhaps by Indian pythons and mugger crocodile. For young or infirm langurs, black eagles, spot-bellied eagle-owls and possibly other larger birds of prey are perhaps not infrequently a threat. Monitor lizards may also feed on purple-faced langurs (possibly through scavenging or picking off the young or sickly). [24] [25] [26]

Conservation

Some conservation strategies consist of improving management of the already protected areas as well as locate and protect new areas and corridors within ranges. Efforts to help increase populations may help survival. It would be beneficial to lower human-langur conflicts. Rope bridges could be established for langurs to move between ranges safely, which may decrease the crossing of power lines and roads. Replanting pine plantations with native species exploited by these langurs, could possibly increase its preferred habitat as well. [14] Public education of conservation to the local people emphasizing compassion and kindness as well as explaining the importance and necessity of these mammals to the ecosystems overall biodiversity. [13]

Related Research Articles

<i>Semnopithecus</i> Genus of Old World monkeys

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. 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.

<span class="mw-page-title-main">Colobinae</span> Subfamily of Old World monkeys

The Colobinae or leaf-eating monkeys are a subfamily of the Old World monkey family that includes 61 species in 11 genera, including the black-and-white colobus, the large-nosed proboscis monkey, and the gray langurs. Some classifications split the colobine monkeys into two tribes, while others split them into three groups. Both classifications put the three African genera Colobus, Piliocolobus, and Procolobus in one group; these genera are distinct in that they have stub thumbs. The various Asian genera are placed into another one or two groups. Analysis of mtDNA confirms the Asian species form two distinct groups, one of langurs and the other of the "odd-nosed" species, but are inconsistent as to the relationships of the gray langurs; some studies suggest that the gray langurs are not closely related to either of these groups, while others place them firmly within the langur group.

<i>Trachypithecus</i> Genus of Old World monkeys

Trachypithecus is a genus of Old World monkeys containing species known as lutungs, langurs, or leaf monkeys. Their range is much of Southeast Asia.

<span class="mw-page-title-main">Gee's golden langur</span> Species of Old World monkey

Gee's golden langur, also known as 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. Long considered sacred by many Himalayan people, the golden langur was first brought to the attention of the Western world by the naturalist Edward Pritchard Gee in the 1950s. Adult males have a cream to golden coat with darker flanks while the females and juveniles are lighter. The golden langur has a black face and a long tail up to 50 cm (19.69 in) in length. It lives in high trees and has a herbivorous diet of fruits, leaves, seeds, buds and flowers. The average group size is eight individuals, with a ratio of several females to each adult male. It is one of the most endangered primate species of India and Bhutan.

<span class="mw-page-title-main">Nilgiri langur</span> Species of Old World monkey

The Nilgiri langur is a langur. This primate has glossy black fur on its body and golden brown fur on its head. It is similar in size and long-tailed like the gray langurs. Females have a white patch of fur on the inner thigh. It typically lives in troops of nine to ten monkeys. Its diet consists of fruits, shoots and leaves. The species is classified as vulnerable due to habitat destruction and poaching for its fur and flesh, the latter believed to have aphrodisiac properties.

<span class="mw-page-title-main">Hatinh langur</span> Species of Old World monkey

The Hatinh langur is a highly threatened Old World monkey found in limestone forests in Vietnam, primarily in the Quảng Bình Province. A recent survey discovered a small population living in the Quảng Trị Province. Contrary to its name, it is not known from the Hà Tĩnh Province. The local Van Kieu minority refer to this monkey as the 'Con Cung', which roughly translates as "black, cliff-dwelling monkey with a long tail". It resembles the closely related François' langur, but its white cheek-stripes typically extend behind the ears onto the nape, and the overall black colour is non-glossy and has a brownish tinge.

<span class="mw-page-title-main">Silvery lutung</span> Species of Old World monkey

The silvery lutung, also known as the silvered leaf monkey or the silvery langur, is an Old World monkey. It is arboreal, living in coastal, mangrove, and riverine forests in Peninsular Malaysia, Sumatra, Borneo, Java, and other nearby islands.

<span class="mw-page-title-main">Delacour's langur</span> Species of Old World monkey

Delacour's langur or Delacour's lutung is a critically endangered species of Old World monkey endemic to northern Vietnam. It is named for French-American ornithologist Jean Théodore Delacour.

<span class="mw-page-title-main">Cat Ba langur</span> The rarest monkey in Asia

The Cat Ba langur, also known as the golden-headed langur, is a critically endangered species of langur endemic to Cát Bà Island, Vietnam. It is among the rarest primates in the world, and possibly the rarest primate in Asia, with population size estimated at less than 70 individuals.

<span class="mw-page-title-main">Phayre's leaf monkey</span> Species of Old World monkey

Phayre's leaf monkey, also known as Phayre's langur, is a species of Old World monkey native to South Asia and Southeast Asia, namely India, Bangladesh, and Myanmar. Populations from further east are now thought to belong to other species. It is listed as Endangered on the IUCN Red List and is threatened by hunting and loss of habitat. The species epithet commemorates Arthur Purves Phayre.

<span class="mw-page-title-main">Northern plains gray langur</span> Species of mammal

The northern plains gray langur, also known as the sacred langur, Bengal sacred langur and Hanuman langur, is a species of primate in the family Cercopithecidae.

<span class="mw-page-title-main">Germain's langur</span> Species of Old World monkey

Germain's langur is an Old World monkey native to Thailand, Myanmar, Cambodia, Laos and Vietnam. The monkey was previously included in Trachypithecus cristatus and Trachypithecus villosus.

The Indochinese black langur is a poorly known Old World monkey native to Laos and adjacent Vietnam. It was originally described as a subspecies of T. auratus, but was later found to be a member of the T. francoisi group, with some maintaining it as a subspecies of that species. In 2001, it was recommended treating it as a separate species.

<span class="mw-page-title-main">Southern plains gray langur</span>

Southern plains gray langur was the common name ascribed to Semnopithecus dussumieri by Mammal Species of the World in 2005. Along with several other Semnopithecus, it had been previously considered a subspecies of the northern plains gray langur, Semnopithecus entellus, i.e., Semnopithecus entellus dussumieri. Subsequent genetic research has revealed that Semnopithecus dussumieri is an invalid taxon. These monkeys live in groups in forests and other rural habitats, with some groups being habituated to human contact and feeding. They are herbivorous, feeding by day mainly on foliage, fruits and flowers, and sleeping at night high in a tree.

<span class="mw-page-title-main">Tufted gray langur</span> Species of Old World monkey

The tufted gray langur, also known as Madras gray langur, and Coromandel sacred langur, is an Old World monkey, one of the species of langurs. This, like other gray langurs, is mainly a leaf-eating monkey. It is found in southeast India and Sri Lanka. It is one of three Semnopithecus species named after characters from The Iliad, S. hector and S. ajax being the others. In Sinhala it is known as හැලි වදුරා.

<span class="mw-page-title-main">Central Highlands of Sri Lanka</span> UNESCO World Heritage Site

Central Highlands of Sri Lanka is a recognised World Heritage Site in Sri Lanka. The site comprises the Peak Wilderness Protected Area, the Horton Plains National Park and the Knuckles Conservation Forest. These are rain forests, where the elevation reaches 2,500 metres (8,200 ft) above sea level. The region harbors a variety of mammal species including the bear monkey, Trachypithecus vetulus monticola, and the Horton Plains slender loris, Loris tardigradus nycticeboides,.

<span class="mw-page-title-main">Western purple-faced langur</span> Subspecies of Old World monkey

The western purple-faced langur, also known as the north lowland wetzone purple-faced langur, is a subspecies of purple-faced langur endemic to Sri Lanka. It lives in the wet zone in western Sri Lanka around the former capital city of Colombo. This subspecies are known to live in tropical rainforest, specifically in an area of Sri Lanka, where it is noted to rain two times more compared to the neighboring region. The subspecies is generally gray-brown with lighter whiskers, a gray rump patch, and dark forearms and legs. These monkeys also have dark brown or black, hairless faces. Their hands and feet are also hairless. When infants, their fur is medium brown to light gray, however it changes to their darker adult colors at between 12 and 16 weeks old. Typical length is between 48 and 67 centimetres excluding tail, with a 59 to 85 centimetres tail. On average, males weigh 8.5 kilograms (19 lb) and females weigh 7.8 kilograms (17 lb). Their average life span is about 26 years if the monkey was held in captivity. Due to their leafy diet, the western purple-faced langur back teeth, include high crowns and pointed cusps to make eating through greenery simpler. They also developed a digestive system that would allow them to break down cellulose in the leaves they eat. Although, leaves are their primary source of food, they also eat fruits and flowers. Female langurs hold a pregnancy for 195–210 days, and after the birth the offsprings are taken closely cared for by the mother until they are about 12–20 weeks old.

<span class="mw-page-title-main">Kaludiya Pokuna Forest</span>

Kaludiya Pokuna Archeological Forest Site is a forest with archeological remains in Kandalama, in the Dry Zone of Sri Lanka. The site has been handed over to the Girls' High School, Kandy in accordance with the "Urumaya Thani Nokaramu" program organized by the Department of Archeology. For the first time in Sri Lanka, a school was given custody of an archeological site.

<span class="mw-page-title-main">White-headed langur</span> Species of monkey

The white-headed langur is a Critically Endangered species of langur endemic to Guangxi, China.

References

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  3. ↑ Post-Disaster Housing Coordination Project (August 2007). "Introduction" (PDF). UN-HABITAT: United Nations Human Settlements Programme - Sri Lanka District Housing Profile (Colombo District). UNICEF. p. 3. Archived from the original (PDF) on 21 February 2016. Retrieved 28 April 2012.
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  7. 1 2 Vandercone, R. (2011). Dietary Shifts, Niche Relationships and Interspecific Competition in Sympatric Grey Langur (Semnopithecus entellus) and Purple-faced Langur (Trachypithecus vetulus) in Sri Lanka. PhD Thesis, Department of Anthropology; University of Washington.
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  10. ↑ Harvey, P.H., Martin, R.D., and Clutton-Brock, T.H. (1987). Life Histories in the Comparative Perspective. In Primate Societies. eds. B.B. Smuts, D.L. Cheney, R.M. Seyfarth, R.W. Wrangham, and T.T. Struhsaker. University of Chicago Press.
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  14. 1 2 3 4 Eschmann, C; R. Moore; K.A.I. Nekaris (2008). "Calling patterns of Western purple-faced langurs (Mammalia: Primates: Cercopithecidea: Trachypithecus vetulus nestor) in a degraded human landscape in Sri Lanka". Contributions to Zoology. 81 (77).
  15. ↑ "Purple-faced Langur | All in Sri Lanka | Dilmah Conservation".
  16. ↑ Wilson, Don E.; Mittermeier, Russell A.; Rylands, Anthony B. (2012). "Introduction". Handbook of the Mammals of the World, Volume 3: Primates (1st ed.). Lynx Edicions. ISBN   978-84-96553-89-7 . Retrieved 2018-08-30.
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  22. ↑ Bauchop, T.; Martucci, R. W. (1968). "The ruminant-like digestion of the langur monkey". Science. 161 (3842): 698–700. Bibcode:1968Sci...161..698B. doi:10.1126/science.161.3842.698. PMID   4969750. S2CID   12069597.
  23. ↑ "Primate Ecology and Behavior Project". Rajnish Vandercone, Arun Bandara, Gihan Jayaweera. Archived from the original on 2015-05-18. Retrieved 1 May 2015.
  24. 1 2 Rajnish P. Vandercone; Chameera Dinadh; Gayan Wijethunga; Kitsiri Ranawana; David T. Rasmussen (2012). "Dietary Diversity and Food Selection in Hanuman Langurs (Semnopithecus entellus) and Purple-Faced Langurs (Trachypithecus vetulus) in the Kaludiyapokuna Forest Reserve in the Dry Zone of Sri Lanka". International Journal of Primatology. 33 (6): 1382–1405. doi:10.1007/s10764-012-9629-9. S2CID   14444114.
  25. ↑ Karunarathna, S., Surasinghe, T., Dissanayake, D., Botejue, M., Gabadage, D., & Madawale, M. (2017). Dietary habits and the predators of the Bengal monitor Varanus bengalensis in Sri Lanka. Biawak, 11(1), 28-39.
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