Overview
Brief Summary
Biology
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Biology
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Comprehensive Description
Description
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Description
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Distribution
Range Description
Trachypithecus vetulus vetulus
This subspecies is found in the rainforests of southern Sri Lanka from south of the Kalu Ganga to about Rama (Groves 2001). It ranges in elevation up to 1,000 m (Molur et al. 2003).
Trachypithecus vetulus nestor
This subspecies is found in western Sri Lanka, from the north of the Kalu Ganga as far north as the rainforest limit (Groves 2001). It ranges in elevation up to 1,000 m (Molur et al. 2003).
Trachypithecus vetulus philbricki
This subspecies is found in the north and east of Sri Lanka in the dry zone, up to 800 m in East Matale and Madukelle Hills (Groves 2001; Molur et al. 2003; W. Dittus et al. pers. comm.).
Trachypithecus vetulus monticola
This subspecies is found in the mountains of central Sri Lanka (Groves 2001). Molur et al. (2003) and W. Dittus (pers. comm.) report that it is found from 1,000 to 2,200 m in elevation.
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Ecology
Habitat
Habitat and Ecology
According to Molur et al. (2003), Trachypithecus vetulus nestor is found in “lowland tropical rainforest, while refugee populations presently inhabit semi-urban and rural home gardens, rubber plantations and areas with adequate canopy cover where these have replaced the original natural forest”; Trachypithecus vetulus monticola is found in “montane tropical rainforest” and Trachypithecus vetulus philbricki is found in “dry evergreen forests, tropical monsoon and deciduous dry forest, confined to moister areas of dry zone with tall closed forest canopy near permanent sources of water”.
Systems
- Terrestrial
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Habitat
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Habitat
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Life History and Behavior
Life Expectancy
Lifespan, longevity, and ageing
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Conservation
Conservation Status
IUCN Red List Assessment
Red List Category
Red List Criteria
Version
Year Assessed
Assessor/s
Reviewer/s
Justification
History
- 2000Endangered
- 1996Vulnerable
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Status
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Status
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Trends
Population
Population Trend
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Threats
Threats
Trachypithecus vetulus vetulus: selective logging (wet zone forests in 1970s), human settlement, hunting, trade, habitat loss, encroachment for agriculture, plantation, and human habitation. Ill-conceived government-organized translocation schemes of langur groups, coming into conflict with man, pose a threat to taxon survival and overall biodiversity. According to government data, during one 42-year period (1956-1993), the country has lost 50% of its forest cover, and more than 50% if the subsequent 10 years (1994-2003) is included. There is a 1:1 relationship between loss of critical habitat and population number. There is also a local trade for meat for food and pelage for making drums at village level for subsistence.
Trachypithecus vetulus monticola: deforestation, fragmentation and habitat loss (crop plantation, development, human settlement) and hunting for subsistence or small scale cash. According to government data, during one 42-year period (1956-1993), the country has lost 50% of its forest cover, and more than 50% if the subsequent 10 years (1994-2003) is included. In addition, 80% of hill country forests were lost to tea plantations in the 19th century. There is a close relationship between loss of critical habitat and population number. There exists a local and domestic trade for meat and skin. Locally pocketed and isolated groups are prone to extinction due to village-level subsistence exploitation.
Trachypithecus vetulus nestor: crop plantations, development (infrastructure, industry), human settlement, deforestation, fragmentation, illegal trade for food, pylon collision, and habitat loss. There is also a local trade at village level for meat, but it is not significant.
Trachypithecus vetulus philbricki: shifting agriculture, deforestation, human settlement, development, hunting for food, habitat loss, and occasional cyclones in far northeastern areas of range. According to government data, during one 42-year period (1956-1993), the country has lost 50% of its forest cover, and more than 50% if the subsequent 10 years (1994-2003) is included. The Mahaweli Development Scheme after 1978 had further reduced available habitat for this taxon. There is a close relationship between loss of critical habitat and population numbers. There exists a local trade for meat and skin. The animals are hunted mainly for subsistence living and trade at local village level. Skins in some areas are used to make drums. This may lead to extinction of subpopulations.
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Threats
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Threats
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Management
Conservation Actions
Trachypithecus vetulus monticola: habitat management, limiting factor management, monitoring, and implementation of extant conservation laws; and the following areas in need of research: surveying, genetics, taxonomy, ecology, behavior, life history, epidemiology, and limiting factors.
Trachypithecus vetulus nestor: habitat management, public education, limiting factor management, work in local communities, and a coordinated Species Management Program; and the following areas in need of research: genetics, taxonomy, life history, behavior, surveying, limiting factor research, epidemiology, and studies to identify viable method of conserving the subspecies.
Trachypithecus vetulus philbricki: habitat management, monitoring, limiting factor management, Population and Habitat Viability Assessment, and implementation of extant laws a priority; and the following areas in need of research: taxonomy, life history, surveying, limiting factor research, epidemiology, trade, zoogeography, population genetics, ecology, and behavior.
Trachypithecus vetulus vetulus: habitat management, public education, government education, implementation of extant conservation laws; and the following areas in need of research: genetics, taxonomy, life history, surveying, ecology and behavioral studies. This taxon is found in many protected areas, but most of the areas have introduced pine species, with very little protection, and much of the remaining forests are rubber or other cash crop plantations. The protected areas are not the size determined, and do not have protection (A. Nekaris pers. comm.). Some conservation has been undertaken for this taxon; systematic conservation education programs were launched in 2001 and have increased awareness of this taxon (A. Nekaris pers. comm.).
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Conservation
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Conservation
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Wikipedia
Purple-faced langur
 | This article may require copy editing for grammar, style, cohesion, tone, or spelling. You can assist by editing it. (May 2011) |
The purple-faced langur (Trachypithecus vetulus), 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.
Contents |
Taxonomy
There are four distinct subspecies of purple-faced langur:
- Southern lowland wetzone purple-faced langur, Trachypithecus vetulus vetulus
- Western purple-faced langur or North Lowland Wetzone purple-faced langur, Trachypithecus vetulus nestor
- Dryzone purple-faced langur, Trachypithecus vetulus philbricki
- Montane purple-faced langur or Bear Monkey, Trachypithecus vetulus monticola
All four subspecies exhibit different cranial and pelage characteristics, as well as body size. They are one of the 25 most endangered primates in the world.[4] Most groups of langurs contain only one adult male.[5][6]
Habitat
The Wet Zone inside Sri Lanka contains closed canopy forests and this is where the purple-faced langur is found. Only 19% of Sri Lanka consists of forested area's. This habitat has decreased from 80% in 1980 to ~25% in 2001.[4] 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 area's. Population's 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.[5][6]
Its range has constricted greatly in the face of human encroachment, although it can still be seen in Sinharaja, Kitulgala, in the mountains at Horton Plains National Park or in the rainforest city of Galle.
Diet
It is said to be very selective in its diet. Within the human domesticated area's fruit such as Jak Arctocarpus heterophylus, rambutan Nephelium lappaceum, banana Musa sexpientum, and mango Mangifera indica consist up to 50% of their diet.[4] Langurs are adapted to get much of their nurtients and energy from complex carbohydrates found in leaves. This happens with the help of a highly specialized stomach that uses sybiotic bacteria to help digest food.[7] Since their diet currently conists more heavily on cultivated fruits that are full of simple sugars instead of complex carbohydrates this could possibly change the gut fauna and it's ability to absorb nutrients.[4] Fruit in this area is also grown seasonally so the Purple Faced Langur could possibly be missing out on a fully complete diet during the off seasons of these fruit.
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 while sunny versus cloudy as well. The least amount of 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.[6]
Conservation
Some conservation strategies consist of improving management of the already protected area's as well as locate and protect new area's 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. Hopefully this will cut back on 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.[6] 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.[8]
References
- ^ Groves, C. (2005). Wilson, D. E.; Reeder, D. M. eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 178. OCLC 62265494. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=12100746.
- ^ Dittus, W., Molur, S. & Nekaris, A. (2008). Trachypithecus vetulus. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 4 January 2009.
- ^ 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. http://www.unhabitat.lk/downloads/COLOMBO.pdf. Retrieved 28 April 2012.
- ^ a b c d Parker, L; V. Nijman, K. A. I. Nekaris (5). "When there is no forest left: fragmentation, local extinction, and small population sizes in the Sri Lankan western purple-faced langur". ENDANGERED SPECIES RESEARCH 5: 29–36.
- ^ a b Rudran, Rasanayagam (January 2007). "A Survey of Sri Lanka's Endangered and Endemic Western Purple-Faced Langur (Trachypithecus Vetulus Nestor)". Primate Conservation 22: 139–144.
- ^ a b c d 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). http://dpc.uba.uva.nl/ctz/vol77/nr02/art01.
- ^ Bauchop, T.; Martucci, R. W. (1968). "The ruminant-like digestion of the langur monkey.". Science: 698–700.
- ^ Rudran, Rasanayagam (January 2007). "A Survey of Sri Lanka's Endangered and Endemic Western purple-faced langur (Trachypithecus Vetulus Nestor)". Primate Conservation 22: 139–144.
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