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Overview

Brief Summary

Biology

The highly folivorous diet of Francois' langur led to the evolution of enlarged salivary glands and a sacculated stomach, which combine to encourage break down and digestion of the tough fibre in leaves, with the help of bacteria living in the upper chamber of the stomach. The lower chamber contains acid as in most mammals, whereas the upper chamber is neutral to create more favourable conditions for the bacteria. Francois' langur is not restricted to eating leaves; it also consumes fruit, seeds, nectar, shoots and insects, varying its diet with seasonal changes in the abundance of these foods (5). Fleshy immature leaves are preferred (5), preventing the langurs from needing to drink frequently (6). The group moves as it feeds, ending each day in a new place. They settle down to sleep at dusk, preferring large trees in good weather, or limestone caves if it's cold or raining (8). An active and noisy species, members of troops indulge in daily mutual grooming in rest periods between feeding (5) (6). The group consists of 4 – 27 (usually around a dozen) individuals and led by the females, who operate a reasonably changeable hierarchy amongst themselves, particularly when it comes to caring for the young (2) (5) (6). There is usually just one adult male in the group who will not participate in caring for the young, except to respond to their distress calls. He will also rarely groom other members of the group, but expects to be groomed himself. Females share responsibility for the infants, who are born singly once a year. They are immediately cared for by 'allomothers' as well as their own mother, who will nurse the young monkey for up to two years before weaning. Once weaned, the bond between mother and infant is no different than between any other members of the group. After three or four years juveniles become sexually mature, and will commonly leave to join another group or to form an all-male bachelor group. Francois' langurs are not fully grown until the age of six or seven (5) (6).
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Description

These langurs have a distinctively tall and pointed crest of black hair on their heads. The fur is black with white lines from the corners of the mouth, across the cheeks to the ears (5). The inquisitive and endearing face of Francois' langur has a short muzzle and prominent brow ridges, giving the expression of permanent surprise. Unlike the colobines' subfamily counterpart, the Cercopithecinae (or 'typical monkeys'), the leaf-eating monkeys do not have cheek pouches, having instead a bulging stomach where slow-to-digest food accumulates. The buttocks of this tree-dwelling species have thickened pads known as ischial callosities, which are separate in females, but joined up in males (6). In common with many Trachypithecus species, the hands and feet are very slim with short thumbs, and the infants' fur is pale ginger-orange, with black on the face and extremities (2) (5).
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Distribution

Range Description

This species occurs in southern China (Chongqing, Guangxi and Guizhou provinces and Chongqing Municipality in Sichuan province), and northeastern Viet Nam. It is found from the Song Hong (Red River) in Viet Nam across the Chinese border as far as the Daming Hills in Guangxi, and about 25°N 105°E in Guizhou (Groves 2001).
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Historic Range:
China (Kwangsi), Indochina

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Geographic Range

The family Cercopithecidae, or old world monkeys, includes leaf monkeys and langurs in the subfamily Colobinae. The subfamily has a wide geographical distribution throughout Asia and Africa. Trachypithecus francoisi, however, is found only in southern Guangxi province in China, northern Vietnam, and west-central Laos.

Biogeographic Regions: oriental (Native )

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Range

With a range in the Indo-Burmese Biodiversity Hotspot, and both the Annamite Range Moist Forests and the Northern Indochina Subtropical Moist Forests Global 200 Ecoregions, Francois' langur is in the company of some of the world's most diverse and threatened species (7). It is found from the Red River in northeastern Vietnam to the Daming Hills in Guangxi and to Xingyi in Guizhou in south-western China (5).
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Physical Description

Morphology

Physical Description

Though males of the species are slightly larger than females, T. francoisi are approximately two feet tall and weigh between 4 and 14 kg. Lengths between 400 and 760 mm are reported.

Pelage varies from uniformly brown, black, or dark gray with a white stripe running from the corner of the mouth to the ear. White is also present in a crest above the eyes, resembling eyebrows, a feature which distinguishes them from species in the genus Presbytis. Young are golden yellow with a black tail, another feature that distinguishes these monkeys from the black young of Presbytis.

These leaf monkeys have small heads and lack cheek pouches. The tail is long, straight, and black with a white tip. Forelegs are much shorter than hind legs with hairless hands and feet that allow easy grasping of branches. Thumbs are well-developed, opposable, and significantly shorter than the thumbs of Presbytis.

This species has not been studied extensively in captivity and information regarding metabolic rate is unavailable.

Range mass: 4.3 to 14 kg.

Range length: 400 to 760 mm.

Sexual Dimorphism: male larger

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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
This species is found in semi-tropical monsoon and moist tropical and subtropical rainforests in limestone (karst) areas (Marsh 1987), though not in cone karsts. The animals utilize the cave formations and overhangs in these areas as shelter from weather, and for refuge. It ranges in elevation up to 1,500 m.

Like other Trachypithecus, T. francoisi is mostly folivorous, with the remainder of its diet consisting of shoots, fruits, flowers, and bark. Males and females reach sexual maturity in five and four years, respectively. Litter size is usually one, and birth intervals for this species are recorded at about 20 months (Nadler et al. 2003).

Systems
  • Terrestrial
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An arboreal species, T. francoisi inhabits densely forested and limestone areas of tropical lowlands and forest valleys. Information regarding exact elevations occupied by these animals is unavailable.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: forest ; rainforest

  • Glover, A. 1938. The Mammals of China and Mongolia. New york: American Museum of Natural History.
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Living above 230 metres - a higher altitude than most langurs - Francois' langur inhabits semi-tropical monsoon forest (5) and well-sheltered rocky areas in karst (limestone) hills (2) (8).
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Trophic Strategy

Food Habits

Trachypithecus francoisi feeds primarily on foliage, especially mature leaves, as well as some fruit and occasional insects. This low protein, high fiber diet requires a modified digestive system. The stomachs of monkeys in the Colobinae subfamily are large and multi-chambered. The forestomach hosts bacteria with cellulose-digesting abilities, allowing these mammals to process plant fibers.

Animal Foods: insects

Plant Foods: leaves; fruit

Primary Diet: herbivore (Folivore )

  • Becher, F., J. Nijboer, J. van der Kuilen, A. Beynen. 2001. Chemical analysis and consistency of faeces produced by captive monkeys (Francois langurs, Trachypithecus francoisi) fed supplemental fibre. Veterinary Quarterly, 23/2: 76-80.
  • Davies, A. 1994. Colobine populations. Pp. 285-310 in J Oates, ed. Colobine Monkeys: Their Ecology Behavior and Evolution. Cambridge: Cambridge University Press.
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Associations

Ecosystem Roles

The diet of primarily mature leaves is unique to T. francoisi, as other leaf eating monkeys prefer young leaves. Other than this impact on forest foliage, little is known about the role of these animals in the ecosystem.

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Predation

Little is known regarding adaptations to avoid predation, antipredator behaviors, or life history modifications as they might relate to predation of T. francoisi. However, a 1994 study suggests that species in this family are not limited by predation, except for being hunted by humans.

  • Isbell, L. 1994. Predation on primates: ecological patterns and evolutionary consequences. Evolutionary Anthropology, 3: 151-154.
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Life History and Behavior

Behavior

Communication and Perception

Vocalization and visual displays have been observed in other members of the genus; however, little is know about the communication of T. francoisi. It is reasonable for us to assume that, as in other primates, visual, tactical, accoustic, and chemical communication are all used by these monkeys.

Communication Channels: visual ; tactile ; acoustic ; chemical

Perception Channels: visual ; acoustic

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Life Expectancy

Lifespan/Longevity

It has been recorded that this species does not survive well in captivity, but specific information is otherwise unavailable.

Range lifespan

Status: captivity:
26.3 (high) years.

  • Collins, L., M. Roberts. 1978. Arboreal folivores in captivity- maintenance of a delicate minority. Pp. 5-12 in G Montgomery, ed. The Ecology of Arboreal Folivores. Washington: Smithsonian Institute.
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Lifespan, longevity, and ageing

Maximum longevity: 26.3 years (captivity) Observations: One wild born specimen of the subspecies *poliocephalus* lived over 26.3 years in captivity (Richard Weigl 2005).
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Reproduction

It is common among colobines for females to initiate sexual behavior, and T. francoisi is no exception. Female proceptive behavior has been documented in the species, though specific information about this behavior is not available.

Trachypithecus francoisi is somewhat of an exception among other species in the family in that the social structure involves primarily one-male groups, in which one male mates with multiple females. Though it has not yet been observed in this species, other species in the genus are known to form all-male groups which occasionally attack one-male groups in order to oust the dominant male and take his place with the females.

Mating System: polygynous ; cooperative breeder

Mating occurs throughout the year, peaking in autumn and winter. The frequency of breeding is unknown. The estrous cycle is 24 days and gestation lasts 6 to 7 months. A female delivers a single offspring once annually. The young are born fully furred and are fairly active. Animals become sexually mature after 4 or 5 years. The species has not been widely studied and the time to weaning and independence of the young is unknown.

Breeding interval: Females are capable of producing young annually.

Breeding season: Trachypithecus francoisi mates year-round, although breeding peaks in autumn and winter

Range number of offspring: 1 to 2.

Average number of offspring: 1.

Range gestation period: 6 to 7 months.

Range age at sexual or reproductive maturity (female): 4 to 5 years.

Range age at sexual or reproductive maturity (male): 4 to 5 years.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization ; viviparous

Average birth mass: 457 g.

Female alloparental care of T. francoisi young has been documented and is a common trait among other Asian colobine species. It is hypothesized that alloparental care provides time and freedom for mothers to forage, improves parenting skills of the alloparent, and ensures the social integration of new infants to the group increasing the likelihood of adoption if the mother is killed. Additionally, it has been suggested that the infrequent but sometimes abusive handling of new infants by the alloparent reduces resource competition for the alloparents’ own offspring.

Other aspects of parental investment are unknown. However, in most primates with similar social structures, females provide the bulk of parental care. They groom, carry, and protect their young. However, males may also play some role in carrying, provisioning and protecting young. The most important parental role of males may be to protect young from potentially infanticidal rival males.

Parental Investment: altricial ; precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Female, Protecting: Male, Female); pre-independence (Provisioning: Female, Protecting: Male, Female); post-independence association with parents; extended period of juvenile learning

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Trachypithecus francoisi

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
EN
Endangered

Red List Criteria
A2cd

Version
3.1

Year Assessed
2008

Assessor/s
Bleisch, B., Manh Ha, N., Khat Quyet, L. & Yongcheng, L.

Reviewer/s
Mittermeier, R.A. & Rylands, A.B. (Primate Red List Authority)

Contributor/s

Justification
Listed as Endangered as there is reason to believe the species has declined by at least 50% over the past 36 years (3 generations, given a generation length of 12 years) due primarily to habitat loss and hunting.

History
  • 2000
    Vulnerable
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Current Listing Status Summary

Status: Endangered
Date Listed: 10/19/1976
Lead Region: Foreign (Region 10) 
Where Listed: Entire


Population detail:

Population location: Entire
Listing status: E

For most current information and documents related to the conservation status and management of Trachypithecus francoisi, see its USFWS Species Profile

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Trachypithecus francoisi is are listed as Endangered by the US Fish and Wildlife service, and the IUCN classifies the species as Vulnerable, with its status dependent on ongoing conservation efforts. CITES lists the species in Appendix I. The subspecies T. f. delacouri of central Viet Nam may be the most endangered monkey in Asia with fewer than 250 individuals alive. It has also been reported that T. f. leucocephalus in southeastern China has a population of only about 400, a result of hunting the monkey for its believed medicinal value. Populations of most other species of Trachypithecus are also declining due to loss of habitat.

Threats to the species include habitat loss to the expansion of agriculture, fuelwood harvesting, warfare, logging, and hunting.

US Federal List: endangered

CITES: appendix i

IUCN Red List of Threatened Species: endangered

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Status

Francois' langur is classified as Vulnerable (VU A1cd+2cd, C2a) on the IUCN Red List 2006 (1) and listed on Appendix II of CITES (4). Although the IUCN Red List recognises three subspecies, Francois's langur or the white side-burned black langur (T. f. francoisi) (VU), the Hatinh langur (T. f. hatinhensis) (EN) and Wulsin's black langur (T. f. ebenus) (DD) (1), current scientific thought is that Francois' langur is monotypic, and that the Hatinh langur and Wulsin's black langur are in fact distinct (2). The Hatinh langur is now considered to be a subspecies of the Indochinese black langur (T. laotum) and Wulsin's black langur is merely a colour morph of T. l. hatinhensis (2).
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Population

Population
This species is widespread, but populations are highly fragmented and isolated. There is no reliable population estimate for Viet Nam, but they are not likely to number more than 500 individuals there; no subpopulation contains more than 50 mature individuals (Nadler et al. 2003). In China, in the southern part of the range (Guangxi Province), the largest population is estimated at 75 individuals in Nonggang Nature Reserve (Li et al. 2007). In the northern part of the range, the largest population is in Mayanghe Nature Reserve, where the population is estimated at roughly 700 individuals. The population estimate for 2003 in China was 1,400-1,650 individuals (Lou et al. in litt.).

Population Trend
Decreasing
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Threats

Major Threats
In Viet Nam, the major threat to this species is hunting, although some populations face pressures from mining and other resource extraction in the karst hills (Nadler et al. 2003). Hunting mainly takes place for traditional “medicines” and to a lesser degree for meat (feeding predominantly Chinese restaurant markets). The isolation of populations due to habitat fragmentation taking place for agricultural development (rice paddies, maize) also threatens the genetic viability of small populations in Viet Nam (Nadler et al. 2003). In Guangxi province, China, the threat of hunting is extremely severe, due to the illegal production of “black ape wine,” which is made specifically from this species; the animals are even imported illegally from Viet Nam for this purpose. Throughout the range in China, populations are threatened by habitat loss due to local cultivation and firewood extraction (Li et al. in prep.). Unmanaged fires that spread into limestone karst habitats also result in the loss of habitat.
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Populations of Francois' langurs have diminished as a result of major changes in land use. In particular, an increase in agricultural land and logging for both timber and fuel wood has reduced the area available to this species. It has also been extensively hunted for food and for use in traditional “medicinal” preparations. Part of the range of Francois' langur was heavily bombed during the Vietnam War, killing individuals as well as damaging and defoliated their habitat (2) (8).
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Management

Conservation Actions

Conservation Actions
This species is listed on CITES Appendix II. Since the 1980s, in China, it has been listed as a Category I species under the Wildlife Protection Act, 1989.

In Viet Nam it occurs in several protected areas, including two national parks. At least two protected areas have been established specifically for this species: Sinh Long-Lung Nhoi Species and Habitat Conservation Area (Tuyen Quang Province) and Nam Xuan Lac Species and Habitat Conservation Area (Bac Kan Province).

In China it is found in 21 protected areas, three of which are national level (Lou et al. in litt.) Also, it is legally protected from hunting, though it faces additional threats there from unrestricted resource extraction and habitat disturbance (Hu et al. 2004). There is a successful captive-breeding program for this species now underway in China in Wushou (Nadler et al. 2003).
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Conservation

The development and maintenance of reserves is crucial to the survival of this species, and combating hunting through the implementation of a ranger system in areas of sanctuary would also be of value. Educating consumers of traditional “medicines” derived from threatened species would not only impact positively on Francois' langur but on many other endangered species (8). T. f. francoisi is found in Xuan Nha, Na Hang, Huu Lien, and Tam Daa Nature Reserves (9), plus Ba Be and Pu Mat National Parks, Vietnam (2).
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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Negative

Negative economic impact to humans, other than the possibility of a retrovirus transmittal, cannot be inferred from the available information.

Negative Impacts: injures humans (carries human disease)

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Economic Importance for Humans: Positive

Trachypithecus francoisi has been used in researching retroviruses that infect a variety of nonhuman primates and can be transmitted to exposed humans. The species is also hunted for its believed medicinal value.

Positive Impacts: source of medicine or drug ; research and education

  • Hussain, A., V. Shanmugam, V. Bhullar, B. Beer, D. Vallet. 2003. Screening for simian foamy virus infection by using a combined antigen Western blot assay: evidence for a wide distribution among Old World primates and identification of four new divergent viruses. Virology, 306/2: 248-257.
  • Massicot, P. 2004. "Animal Info- Francois' Leaf Monkey" (On-line). Accessed October 12, 2004 at http://www.animalinfo.org/species/primate/tracfran.htm.
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Wikipedia

François' langur

François' langur (Trachypithecus francoisi), also known as Francois' leaf monkey, Tonkin leaf monkey, or white side-burned black langur[3] is a species of lutung and the type species of its species group. It is the least studied of the species belonging to the Colobinae subfamily.[4]

The species is distributed from Southwestern China to northeastern Vietnam. The total number of wild individuals is unknown, but there are believed to be less than 500 left in Vietnam and 1,400–1,650 in China.[2] There are about 60 langurs in captivity in North American zoos. The species is named after Auguste François (1857–1935) who was the French Consul at Lungchow in southern China.[5]

Physical description[edit]

François' langur is a medium sized primate with black silky hair. It has very distinct white sideburns that grow down from its ears to the corners of its cheeks.[3] A morphological specialization of François' langur is its complex stomach, made up of four separate chambers. This is a necessary adaptation for the digestion of its folivorous diet.[4]

This species shows sexual dimorphism in its size. Males have a head-body length of 55–64 cm (22–25 in), while females are only 47–59 cm (19–23 in) in length. Males likewise have longer tails of 82–96 cm (32–38 in) compared to the 74–89 cm (29–35 in) for females. Males are significantly heavier than females, weighing 6.5–7.2 kg (14–16 lb) compared to 5.5–5.9 kg (12–13 lb) for females. Infants weigh 0.45–0.50 kg (16–18 oz) at birth.[3]

François' langur has large salivary glands to begin the digestion of tough leaf fibers. A more notable evolutionary adaptation seen in this langur is the sacculated stomach with two chambers. In the upper chamber, bacteria help to continue the breakdown of fibers started by the saliva. The upper chamber has a relatively normal pH, to create favorable conditions for bacterial growth. The lower chamber is similar to that of other mammals, in that it contains the acids that finish the breakdown of food components.[3]

Behavior[edit]

Trachypithecus Francoisi relaxing on a stump at the Los Angeles Zoo.

François' langur is diurnal and spends most of the day resting and foraging.[6] One study investigated time distribution across activities in a disturbed environment, showing resting 35.41%, foraging 31.67%, traveling 14.44%, huddling 9.61%, playing 8.54%, and grooming 0.33%.[6] Traveling, playing, grooming and huddling are more dependent on the season.[7] Interestingly it has been found that grooming occurs in all seasons but spring.[6] François' langur spends a greater part of its day travelling during the winter (20.12%) and huddling in the spring (14.62%).[7]

François' langur lives in groups of four to twenty-seven langurs, but will usually be found in groups of around twelve.[3][8] It lives in a matriarchal society where the females lead the group. Within the society, the females perform alloparenting, sharing parenting responsibilities with one another, and are philopatric to the group.[8] Males within the group take no part in the raising of the young, the young males will leave the group before reaching sexual maturity.[8] Young langurs are nursed for up to two years before being weaned, and once weaned the relationship amongst the relatives becomes that of any other member of a given group.[3]

Over 50% of François' langur's diet is made up of leaves. It will also consume fruits (17.2%), seeds (14.2%), flowers, stems, roots, bark and occasionally minerals and insects from rock surfaces and cliffs. This langur consumes its favorite food, young leaves, at the highest rate during the dry season, April through September; between October and March when young leaves are less common, the langur supplements its diet with seeds, petioles, and stems.[4]

François' langur is selective in its diet, in Nonggang Nature Reserve, China, it primarily eats the young leaves of ten different species of plant, only two of which are common within the reserve. Its diet includes Pithecellobium clypearia, Ficus nervosa, Garcinia pauncinervis, Sinosideroxylon pedunculatum, F. microcarpa, Miliusa chunni, Securidaca inappendiculata, Bauhinia sp., and Canthium dicoccum. Though these are the preferred plant species, it will still consume other plant species opportunistically.[4] Another study on François' langur in a fragmented habitat found that it preferred on just four plant species: litse, Litsea glutinosa; seatung, Pittosporum glabratum; Cipadessa cinerascens; and Chinese desmos, Desmos chinensis. The study showed that the langur spent 61.6% of its feeding time on these four plant species, and 38.4% of its time on 36 other known species.[9]

Habitat and distribution[edit]

The preferred habitat of François' langur is a karst topography; limestone cliffs and caves of tropical and subtropical zones.[10] By living on these limestone cliffs, the langur is at an advantage when it comes to sleeping arrangements. It sleeps either on ledges or in caves, with its preference being in the cave.[11] François' langur has also been known to find sleeping sights in areas where the terrain is above 60 °F (16 °C), within evergreen forests.[12] By living and sleeping in these limestone caves and cliffs, far from flat land, the langur has greatly reduced its rate of predation.[12] It exhibits cryptic behavior and becomes very vigilant upon entry to the cave for final resting as a tactic to avoid any predators.[11] In addition to this it also demonstrates a loud call to declare its territorial spacing.[13] François' langur will also choose its sleeping habitat depending upon foraging availability. It will choose sleeping sites that are close to potential foraging sites, to maximize energy and reduce travel costs.[12] It is important to note that sleeping sites are not located in the heart of foraging sites, but are within reasonable proximity, as the preferred nesting and foraging sites do not completely line up with one another.[12] When it does go to forage, it tends to travel along the same route and returns to the same sleeping site consecutive nights to avoid predation.[11] François' langur has been known to have approximately 6-10 regularly used sleeping sites that are used at various points throughout the year as water and food resources fluctuate.[12]

François' langur has a restricted range of areas in which it can inhabit. It is primarily found in Southwest China and northern Vietnam. The majority of scientific studies of François' langur in the wild take place in the Nonggang Nature Reserve and the Fusui Nature Reserve in Guangxi Province, China.[8] The average home range size of this species is 19 hectares (230,000 sq yd) and its day range size is 341–577 square metres (3,670–6,210 sq ft).[8] In general, the low quality of its folivorous diet leads to nutritional stress, a smaller home range size and reduced daily travel time. The largest group of langurs reported numbered 500-600 individuals, and was found in the Mayanghe National Nature Reserve.[6] The average group size is approximately 4-27.[3] The Fusui Nature Reserve reported in 2009 that François' langur population had declined 73% in the previous 5 years, thus lessening their distribution even more.[8] Recent census numbers have concluded that it is now limited to 14 localities in 10 different counties.[9]

Conservation status[edit]

The population of François' langur has been on a steady decline for the past 30 years. Of the many factors threatening the survival of François' langur today, hunting has had one of the largest impacts.[10] In Nonggang, where François' Langur is most prevalent, the natives believe that the langur has medicinal values, and have hunted them to make wine out of their bones, which they believe could cure fatigue and rheumatism.[10] In Guangxi province there has been an estimated 90% decline in numbers since the 1980s, a 2002-2003 survey found 307 individuals in 14 populations remained.[10] In 1983, the estimated population of François' langur was 4,000-5,000. In the 1970s, hunting records recorded more than 1,400 langurs killed and in the 1980s more than 1,500 langurs were killed.

Another threat to François' langur is the destruction of its habitat. The langur lives on limestone cliffs and when farmers look to cultivate their land they will light fires on the lower slopes.[3] Limestone is particularly susceptible to fire; therefore this practice not only destroys its habitats but also causes major food shortages for the langur because its diet is primarily folivorous.[10] The primary predators of François' langur are both terrestrial and aerial.[11] The clouded leopard is a potential predator to the langur but the clouded leopard's numbers are so low that they are not its greatest threat. Aerial predators such as the Crested Serpent Eagle and the Mountain Hawk-eagle are a greater threat to François' langurs of Nonggang, especially to their young.[11]

The actions being taken towards the conservation of this species and its habitat is still minimal. Its current population size is less than 2,500 individuals.[10] A plan to protect the forest and ban hunting, called the Conservation Action Plan, was drafted in 1996 but has still yet to be implemented. In order to protect the langur, not only does protection from hunting need to be implemented but its habitats must be protected as well.[3] In 2003, the National Forestry Bureau acknowledged the rapid decline in François' langur and agreed to increase law enforcement in this area to help protect the langur from hunters.[10] In addition, the Asia Developmental Bank has begun helping the residents that live in close proximity to the habitats of the langur build biogas facilities to reduce the fuel wood collection and thus possibly reduce the number of fires.[10] And finally, a current project is underway by the Global Environmental facility to protect the Nonggang National and Dmingshan Natural Reserves and the langurs living within.[10]

References[edit]

  1. ^ Groves, C. P. (2005). Wilson, D. E.; Reeder, D. M, eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. OCLC 62265494. ISBN 0-801-88221-4. 
  2. ^ a b Bleisch, B., Manh Ha, N., Khat Quyet, L. & Yongcheng, L. (2008). Trachypithecus francoisi. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 4 January 2009.
  3. ^ a b c d e f g h i "Arkive - Francois Langur". Arkive.org. Retrieved 25 March 2012. 
  4. ^ a b c d Zhou, Qihai, Fuwen, W., Li, M., Chengming, H., Luo, B. (2006). "Diet and food choice of (Trachypithecus francoisi) in the Nonggang Nature Reserve, China". International Journal of Primatology 27: 1441–1458. doi:10.1007/s10764-006-9082-8. 
  5. ^ The Eponym Dictionary of Mammals - Page 141 Bo Beolens, Michael Watkins, Michael Grayson - 2009 "François' Leaf Monkey Trachypithecus francoisi Pousargues, 1898 [Alt. François' Langur] Auguste François (1857–1935) was the French Consul at Lungchow in southern China, where he was the first person to bring this monkey to the ..."
  6. ^ a b c d Yang, Lou, Minghai, Z., Jianzhang, M., Ankang, W., Shusen, Z. (2007). "Time budget of daily activity of Francois’ langur (Trachypithecus francoisi) in disturbance habitat". Acta Ecologica Sinica 27: 1715–1722. doi:10.1016/S1872-2032(07)60043-2. 
  7. ^ a b Zhou, Qihai, Wei, F., Chengming, H., Li, M., Ren, B., Luo, B. (2007b). "Seasonal Variation in the Activity Patterns and Time Budgets of Trachypithecus francoisi in the Nonggang Nature Reserve, China". International Journal of Primatology 28: 657–671. doi:10.1007/s10764-007-9144-6. 
  8. ^ a b c d e f Zhou, Qihai, Chengming, H., Li, Y., Cai, X. (2007a). "Ranging behavior of the Francois langur (Trachypithecus francoisi) in the Fusui nature Reserve, China". Primates 48 (4): 320–323. doi:10.1007/s10329-006-0027-9. PMID 17171396. 
  9. ^ a b Youbang, L.; Ping D.; Pingding J.; Wood C.; Chengming H. (June 2009). "Dietary response of a group of Francois' langur Trachypithecus francoisi in a fragmented habitat in the county of Fusui, China". Wildlife Biology. 2 15: 137. doi:10.2981/08-006. 
  10. ^ a b c d e f g h i Li, Youbang, Huang, C., Ding, P., Tang, Z., and Wood. (2007). "Dramatic decline in Francois' langur (Trachypithecus francoisi) in Guangxi Province, China". Oryx 41: 38–43. doi:10.1017/S0030605307001500. 
  11. ^ a b c d e Zhou, Qihai, Chengming, H., Ming, L., Fuwen, W. (2009). "Sleeping site use by Trachypithecus francoisi at Nonggang Nature Reserve China". International Journal of Primatology 30: 353–365. doi:10.1007/s10764-009-9348-z. 
  12. ^ a b c d e Shuangling, Wang; Yang Luo; Guofa Cui (2011). "Sleeping site selection of Francois's langur in two habitats in Mayanghe National Nature Reserve, Guizhou, China". Primates 51: 51/2. doi:10.1007/s10329-010-0218-2. Retrieved 25 March 2012. 
  13. ^ Li, Zhaoyuan and E. Rogers. (1993). "Time budgets of Presbytis leucocephalus". Acta Theriol Sin 12: 7–13. 
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