Phayre's Leaf-monkey (Trachypithecus phayrei)

MORPHOLOGY:
This species has a sacculated stomach to assist in the breakdown of cellulose. Phayre's leaf-monkey has enlarged salivary glands to assist it in breaking down food. The dental formula of Phayre's leaf-monkey is 2:1:2:3 on both the upper and lower jaws (Ankel-Simons, 2000). Males have larger canines than females (Pan et al., 1993). The length of the head and body range from 44-61 centimeters and tail length for this species ranges from 65-86 centimeters (Choudhury, 1987). The average body mass of an adult male Phayre's leaf-monkey is around 7.3 kilograms, and for the female it is around 6.2 kilograms (Fleagle, 1988). The pelage color for Phayre's leaf-monkey is dark ashy-bluish brown on the dorsal side and whitish on the ventral side (Choudhury, 1987). The head and tail ends of this species are darker than the rest of the body (Choudhury, 1987). Srivastava (1999) describes the upper arms, legs, and tail as being silvery gray in coloration. The lips and the area around each of the eyes are whitish (Choudhury, 1987). Infants are straw colored (Roonwal and Mohnot, 1977). Srivastava (1999) describes the infants as being orange in color that begins to change after 3 months of age. This species has an extended cap of hair on the head that occurs in all individual except newborn infants (Srivastava, 1999).

This species has three subspecies each having differing pelage colorations:

• Trachypithecus phayrei phayrei: The dorsal side either dark brown, buffy, or gray-brown and the ventral side is gray or whitish in coloration (Groves, 2001). Around the eye there is a white ring (Groves, 2001).
• Trachypithecus phayrei crepusculus: This subspecies has a body coloration of gray to gray-fawn or silvery brown to nearly yellow (Groves, 2001). This subspecies has a forehead that is brown becoming lighter over the crown, being creamy sometimes on the nape (Groves, 2001). The hands and feet are black (Groves, 2001). Has white eye- rings and a small are of depigmentation around the mouth (Groves, 2001).
• Trachypithecus phayrei shanicus: The overall color of this subspecies is described as fawn, with a trace of lightening on the nape (Groves, 2001). Hands and feet are slightly darker than the rest of the body (Groves, 2001). Around the eyes the white is restricted to the inner side and the depigmented area around the mouth is wide (Groves, 2001). A whorl is found behind the brows, but there is no crest on the crown (Groves, 2001).

RANGE:
Phayre's leaf-monkey is found in the countries of Bangladesh, Burma, China, India, Thailand, and Vietnam (Srivastava, 1999; Roonwal and Mohnot, 1977; Gupta and Kumar, 1994; Stanford, 1988; Ruggeri and Timmins, 1995/1996). In India, this species is found in Tripura, Mizoram, and Assam (Choudhury, 1987, 1994; Mukherjee, 1982; Srivastava, 1999). In Assam, Phayre's leaf-monkey is found in the districts of Cachar, Hailakandi, and Karimganj (Choudhury, 1996). This species is found in Huai Kha Khaeng Reserve, Thailand and in Pidaung and Pegu Yoma Reserves in Burma (MacKinnon and MacKinnon, 1987). This species lives in primary and secondary forests, and also on tea estates where bamboo thickets are found (Wolfheim, 1983; cited in Nisbett and Ciochon, 1993). In Assam Phayre's leaf-monkey was found to live in depleted evergreen forests containing bamboo, favoring habitats dominated by the shrub Macaranga denticulata and the herb Alpinia allughas (Choudhury, 1987, 1994, 1996). In Mizoram this species was found in secondary forests and a dense bamboo forest with a few scattered trees (Raman et al., 1995). In Bangladesh this species lives in semi- evergreen forests and semi-deciduous/evergreen forests (Feeroz et al., 1995; Gittins and Akonda, 1982). In Vietnam, this species is found in the localities of: Phu Quy, Muong Cha, Phu Yen, Lang Chanh, Quan Hoa, Nghia Dung, and Quy Chau (Nisbett and Ciochon, 1993; Wolfheim, 1983). Ratajszczak (1988) reports that this species is found in Cuc Phuong National Park in Vietnam. In Burma, this species lives in dense high forests and in bamboo forests along hillsides and along the banks of streams (Roonwal and Mohnot, 1977). In Thailand, Phayre's leaf-monkey lives in evergreen forests, 15-50 meters above the ground (Roonwal and Mohnot, 1977). Phayre's leaf- monkey is found in higher densities in mixed-species plantations than in monoculture plantations (Gupta, 1997).

This species has three subspecies each having a differing range:

• Trachypithecus phayrei phayrei: This subspecies is found from Pegu north through Arakan to Tripura and southern Assam, India and in eastern Bangladesh (Groves, 2001).
• Trachypithecus phayrei crepusculus: This subspecies is found in Bangladesh, southern China, southwestern Laos, central and northwestern Thailand, and northern Vietnam (Groves, 2001). In Bangladesh this subspecies occurs to the south of the range of the subspecies Trachypithecus phayrei phayrei (Groves, 2001).
• Trachypithecus phayrei shanicus: This subspecies is found from northern Burma into southern Yunnan, China in the Yingjiang-Namting River and Tunchong- Homushu Pass Districts (Groves, 2001).

ECOLOGY:
Phayre's leaf-monkey is a folivorous species (Ahsan, 1994; Roonwal and Mohnot, 1977; Gupta and Kumar, 1994; Stanford, 1988; Choudhury, 1994; Gupta, 1996; Bose and Bhattacharjee, 2002). This species prefers to consume immature leaves to more mature ones (Bose and Bhattacharjee, 2002). In the Inner Line Reserve Forest of Assam, this species was found to mainly consume bamboo shoots (Srivastava, 1999). In southern Assam the three most preferred food items were Teinestachum dulloea, Dendrocalamus griffithii, and Mokania micrantha (Bose and Bhattacharjee, 2002). At Sipahijala, Tripura, young rubber shoots are an important part of the diet during the dry season (Srivastava, 1999). Gupta (1997) found that 38% of the total time feeding was spent on feeding on plantation species. An exotic plantation species, Akashmani (Acacia auriculiformis), accounted for 18.3% of the time feeding on plantation species (Gupta, 1997). There are two feeding peaks for this species, one in the early morning and one in the late afternoon (Srivastava, 1999). Phayre's leaf-monkey will sometimes break-up into subgroups when foraging (Srivastava, 1999; Choudhury, 1994). Groups will spread out far when foraging (Ahsan, 1994). More time is devoted to feeding during the winter months (36.9%) than in summer (33.6%) or the monsoon (31.1%) months (Gupta and Kumar, 1994).

Gupta and Kumar (1994) found that in Gumti Wildlife Sanctuary, Tripura, India, the diet consists of young and mature leaves, ripe and unripe fruits, seeds, petioles, flowers, and gums. Gupta and Kumar (1994) over an eight month study found that young leaves consisted of 48.5% of the diet, followed by the young pods and seeds of two leguminous species (Albizzia procera and Albizzia lebbek), unripe and partly ripe fruit of two Ficus species accounted for 5.2% of the diet, and the last 20.6% of the diet consisted of petioles, gums, and flowers. Young leaves were consumed most in June (81.7%) and least in March (22.0%) (Gupta and Kumar, 1994). Seeds were found to be more in the months of January, February, and March when eating young leaves was low (Gupta and Kumar, 1994). Feeding on mature leaves was low, only consisting of feeding on the leaves of the bamboo species Melocanna bambusoides (Gupta and Kumar, 1994). Gupta and Kumar (1994) found that the feeding on young leaves depended on their abundance and not their availability. The most important food sources at Gumti Wildlife Sanctuary were Albizzia procera, Melocanna bambusoides, Callicarpa arborea, and Albizzia stipulata, Albizzia lebbek (Gupta and Kumar, 1994). Albizzia procera was used the most with its young leaves, pods and seeds, and gum being utilized (Gupta and Kumar, 1994).

Group sizes range from 3 to 30 individuals. In Yunnan, China, group sizes for this species were found to range from 30-40 individuals (Zhen, 1991; cited in Pan et al., 1993). He and Yang (1982; cited in Pan et al., 1993) found that group sizes ranged from 4-8 individuals. In Bangladesh, the mean group size was found to be 11 individuals (Ahsan, 1994). In Rajkandi Reserve Forest, Bangladesh, group sizes were found to average 8.8 individuals (Stanford, 1988). This is an arboreal and a diurnal species, although it will move around the ground occasionally to move or to feed (Choudhury, 1994). Groups have a relatively small home range size due to a high percentage of folivory (Gupta, 2002). Daily activity consists of feeding (34.9%), resting (21.15), traveling (14.4%), and other (29.5%, playing, grooming, etc.) (Gupta and Kumar, 1994). More time is spent feeding and less time resting during the winter months (Gupta and Kumar, 1994). Gupta (1997) found that in another study (12 months), in Tripura, India, daily activity consisted of 41.7% feeding, 28.3% resting, 8.2% traveling, and 21.8% other activities (grooming, calling, playing, suckling, aunting, etc.). Bose and Bhattacharjee (2002) found that in southern Assam, group daily activity consisted of 39.4% feeding, 14.8% moving (traveling), 34.4% resting, 7.2% grooming, 1% playing, and 3.2% other activities. Groups will awake shortly before dawn, feed, then find a place to rest (Choudhury, 1994). In the late afternoon, groups will feed again (Choudhury, 1994). During the winter months, individuals will bask in the sun like capped langurs (Choudhury, 1994). Sleeping sites range in height from 8 to 29 meters (Gupta, 2002).

LOCOMOTION:
Phayre's leaf-monkey moves through the forest quadrupedally (Fleagle, 1988).

SOCIAL BEHAVIOR:
Phayre's leaf-monkey has either a unimale or a multimale-multifemale social system; in the multimale-multifemale usually there are two males (Gupta and Kumar, 1994; Choudhury, 1994). The number of females in a group will range from 3 to 6 (Gupta and Kumar, 1994). Solitary individuals have been reported for this species (Srivastava, 1999). This is a territorial species and will defend its territory against conspecific groups. When a group is alarmed, the females will grab their infants and run throughout the forest, leaping from tree to tree while a male stays behind to watch and bark at the intruder (Roonwal and Mohnot, 1977). Infants will be transferred between females (Srivastava, 1999). Gupta (2000) observed a group's reaction to a dead member of the group and found that they remained close to the body, touching and caressing it. Gupta (2000) also found that a neighboring group also came near the body, but there was no aggression between the groups, which is usually expected. Neighboring groups may be related and the second group may have protected the first group from predators because the dead body was on the ground and Phayre's leaf-monkey rarely descends to the ground (Gupta, 2000). Remaining close to the body may reduce the stress of the group members (Gupta, 2000).

In the West Bhanugach Reserve Forest of Sylhet, Bangladesh, Phayre's leaf-monkey is sympatric with the capped langur, Trachypithecus pileatus (Feeroz et al., 1995). This species is also sympatric with the capped langur in Rajkandi Reserve Forest where they will feed in the same or adjacent trees (Stanford, 1988).

Humans, Homo sapiens, predate upon Phayre's leaf-monkey (Roonwal and Mohnot, 1977). Leopards, Panthera pardus, is a potential predator of this species (Stanford, 1988).

VOCAL COMMUNICATION:
loud call: This call is described as being a high pitched roar (Stanford, 1991).

whoo call: This is a soft warning call emitted by the adult male upon detection of a predator (Srivastava, 1999).

cheng-kong call: This is a two-phased honking call emitted by the adult male to bring the group together (Srivastava, 1999).

OLFACTORY COMMUNICATION:

VISUAL COMMUNICATION:

TACTILE COMMUNICATION:
social grooming: This is when one individual grooms another and is used to reinforce the bonds between individuals.

REPRODUCTION:
Phayre's leaf-monkey gives birth to a single offspring. Females will experience 3.57 menstrual cycles to conception (Lu et al., 2010). Average gestation length for this species was found to be 205.3 days (Lu et al., 2010).

REFERENCES:
Ahsan, M.F. 1994. Feeding ecology of the primates of Bangladesh. in Current Primatology Volume 1: Ecology and Evolution. eds. B. Thierry, J.R. Anderson, J.J. Roeder, and N. Herrenschmidt. Universite Louis Pasteur: Strasbourg.

Ankel-Simons, F. 2000. Primate Anatomy. Academic Press: San Diego.

Bose, J. and Bhattacharjee, P.C. 2002. Behavioural profile of a troop of Phayre's leaf monkey (Trachypithecus phayrei) in a fragmented and disturbed habitat, northeast India. (abstract) XIX Congress of the International Primatological Society. Beijing, China, 0287.

Burton, F. 1995. The Multimedia Guide to the Non-human Primates. Prentice- Hall Canada Inc.

Choudhury, A. 1987. Notes on the distribution and conservation of Phayre's leaf monkey and hoolock gibbon in India. Tiger Paper. Vol. 14(2), 2-6.

Choudhury, A. 1994. Phayre's leaf monkey (Presbytis phayrei) in northeastern India. TigerPaper. Vol. 21(3), 1-4.

Choudhury, A. 1996. Primates in Assam – Status and conservation. TigerPaper. Vol. 23(3), 14-17.

Feeroz, M.M., Islam, M.A., and Kabir, M. 1995. Status, distribution and conservation of non-human primates of Bangladesh. Kyoto University Overseas Research Reports of Studies on Asian Non-human Primates. Vol. 9, 73-82.

Fleagle, J. G. 1988. Primate Adaptation and Evolution. Academic Press: New York.

Gittins, S.P. and Akonda, A.W. 1982. What survives in Bangladesh? Oryx. Vol. 16(3), 275-281.

Groves, C.P. 2001. Primate Taxonomy. Smithsonian Institute Press: Washington, D.C.

Gupta, A.K. 1996. Dietary differences between Phayre's langur (Trachypithecus phayrei) groups in Gumti and Sepahijala Wildlife Sanctuary, north east India: Responses to food availability, adaptability, and human influence. (abstract) IPS/ASP Congress abstracts. Madison, WI, USA, 161.

Gupta, A.K. 1997. Importance of forestry plantations for conservation of Phayre's langur (Trachypithecus phayrei) in north-east India. Tropical Biodiversity. Vol. 4(2), 187-195.

Gupta, A.K. 2000. Behaviour of Phayre's langur (Trachypithecus phayrei) on the death of one adult female. Mammalia. Vol. 64(4), 477-480.

Gupta, A.K. 2002. Ranging behaviour of Phayre's langur Trachypithecus phayrei. (abstract) XIX Congress of the International Primatological Society. Beijing, China, 0272.

Gupta, A. K. and Kumar, A. 1994. Feeding ecology and conservation of the Phayre's leaf monkey Presbytis phayrei in northeast India. Biological Conservation. Vol. 69, 301-306.

He, C.R. and Yang, D.H. 1982. Preliminary studies on the biology of Presbytis phayrei. Zoological Research. Vol. 3(suppl), 349-354.

Lu, A., Borries, C., Czekala, N.M., and Beehner, J.C. 2010. Reproductive characteristics of wild female Phayre's leaf monkeys. American Journal of Primatology. Vol. 72(12), 1073-1081.

MacKinnon, J. and MacKinnon, K. 1987. Conservation status of the primates of the Indo- Chinese subregion. Primate Conservation. Vol. 8, 187-195.

Mukherjee, R.P. 1982. Phayre's leaf monkey of Tripura. Journal of the Bombay Natural History Society. Vol. 79(1), 47-56.

Nisbett, R.A. and Ciochon, R.L. 1993. Primates in northern Viet Nam: A review of the ecology and conservation status of extant species, with notes on Pleistocene localities. International Journal of Primatology. Vol. 14(5), 765-795.

Pan, R.L., Peng, Y.Z., Ye, Z.Z., and Yu, F.H. 1993. Sexual dimorphism of skull and dentintion in Phayre's leaf monkey (Presbytis phayrei). Folia Primatologica. Vol. 60, 230-236.

Raman, T.R.S., Mishra, C., and Johnsingh, A.J.T. 1995. Survey of primates in Mizoram, north-east India. Primate Conservation. Vol. 16, 59-62.

Ratajszczak, R. 1988. Notes on the current status and conservation of primates in Vietnam. Primate Conservation. Vol. 9, 134-136.

Roonwal, M.L. and Mohnot, S.M. 1977. Primates of South Asia: Ecology, Sociobiology, and Behavior. Harvard University Press: Cambridge, Mass.

Ruggeri, N. and Timmins, R.J. 1995/1996. An initial summary of diurnal primate status in Laos. Asian Primates. Vol. 5(3/4), 1-3.

Srivastava, A. 1999. Primates of Northeast India. Megadiversity Press: Bikaner, India.

Stanford, C.B. 1988. Ecology of the capped langur and Phayre's leaf monkey in Bangladesh. Primate Conservation. Vol. 9, 125-128.

Stanford, C.B. 1991. The capped langur in Bangladesh: Behavioral ecology and reproductive tactics. Contributions to Primatology. Vol. 26, 1-179.

Wolfheim, J.H. 1983. Primates of the World. University of Washington Press: Seattle.

Zhen, X.J. 1991. A preliminary study of Phayre's leaf monkey (Presbytis phayrei shanicus). MD thesis, Kunming Institute of Zoology.

Last Updated: January 11, 2011.
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