Francois' Leaf-monkey (Trachypithecus francoisi)
The body mass for Francois' leaf-monkey is between 7 and 8 kilograms. The head and body length ranges from 470-635 millimeters and the tail length ranges from 740-960 millimeters (Groves, 2001). The pelage color for this species is mostly black with white running from the corner of the mouth along the face to the upper edge of the ear pinna (Groves, 2001). The crown has a tall, pointed crest of hair that whorls on both sides of the midline of the nape (Groves, 2001). The newborns are orange colored (Krishnamurthy, 1992). This species has a sacculated stomach to assist in the breakdown of cellulose. Francois' leaf-monkey has enlarged salivary glands to assist it in breaking down food. This species has slim hands and feet and reduced thumbs. The dental formula of Francois' leaf-monkey is 2:1:2:3 on both the upper and lower jaws (Ankel-Simons, 2000).
Francois' leaf-monkey is found in the countries of China and Vietnam (Le and Campbell, 1993/1994). The range extends from northeastern Vietnam (Red River) into southwestern China (Daming Hills in Guangxi and Xingyi in Guizhou) (Le and Campbell, 1993/1994; Groves, 2001). In Vietnam, this species is common in Cao Bang and adjacent provinces (Ratajszczak et al., 1990). In China, Francois' leaf-monkey is found in relatively high altitude (228 meters above sea level) as compared to other leaf-monkeys (Li, 1993). This species lives in semi tropical monsoon and moist tropical rainforests in mountainous areas (Marsh, 1987).
Francois' leaf-monkey is a folivorous species, but fruits, seeds, nectar, shoots, and insects are also consumed. This species prefers immature leaves over more mature ones. Group sizes range from 4 to 27 individuals. This is an arboreal and diurnal species. Francois' leaf-monkey will sleep in large trees or in caves.
Francois' leaf-monkey moves through the forest quadrupedally (Fleagle, 1988).
Francois' leaf-monkey has a unimale social system. Males disperse from the group shortly after puberty. Females of a group have a hierarchy that is variable (Bocian and Carter, 1999).
Females allow other females to carry and to care for their young (allomothering) (Fleagle, 1988; Rich, 1983; Krishnamurthy, 1992). Mothers will hand over their infants when feeding (Krishnamurthy, 1992). Allomothering behavioral patterns include: cuddle, embrace, social grooming, kiss, carrying and protecting the infant, and establishing physical contact (Krishnamurthy, 1992). Rich (1983) suggests that allomothering may be low when there is stress or unfamiliarity with group members on the part of the mother. The adult male of the group will not spend much time caring for the infants of the group, but will respond to distress calls uttered by infants (Rich, 1983; Krishnamurthy, 1992).
whoop call: This is emitted by males and is used to demarcate the group's territory. This call is acoustically similar to the same call found in the common langur, Semnopithecus entellus (Krishnamurthy, 1991).
ka: This call is emitted by the adult male. This call functions as an alarm call.
threat bark: This call is heard during allomothering behavior (Krishnamurthy, 1992).
contact greet: This call is heard during allomothering behavior (Krishnamurthy, 1992).
grunt: This call is heard during allomothering behavior (Krishnamurthy, 1992).
scream: This call is heard during allomothering behavior (Krishnamurthy, 1992).
squeal: This call is heard during allomothering behavior (Krishnamurthy, 1992).
social grooming: This is when one individual grooms another and is used to reinforce the bonds between individuals.
Francois' leaf-monkey gives birth to a single offspring.
Ankel-Simons, F. 2000. Primate Anatomy. Academic Press: San Diego.
Bocian, D. and Carter, A. 1999. Integration of a female Francois langur (Presbytis francoisi francoisi) into an existing captive group. (abstract) American Journal of Primatology. Vol. 49, 37.
Burton, F. 1995. The Multimedia Guide to the Non-human Primates. Prentice-Hall Canada Inc.
Fleagle, J. G. 1988. Primate Adaptation and Evolution. Academic Press: New York.
Groves, C.P. 2001. Primate Taxonomy. Smithsonian Institute Press: Washington, D.C.
Krishnamurthy, R. 1991. Vocalization patterns of captive Francois langurs (Presbytis francoisi). (abstract) American Journal of Primatology. Vol. 24, 113.
Krishnamurthy, R. 1992. Allomothering behavior and the associated vocalization patterns among captive Francois' langurs (Presbytis francoisi). (abstract) American Journal of Primatology. Vol. 27, 40-41.
Le, X.C. and Campbell, B. 1993/1994. Population status of Trachypithecus francoisi poliocephalus in Cat Ba National Park. Asian Primates. Vol. 3(3/4), 16-20.
Li, Z.-Y. 1993. Preliminary investigation of the habitats of Presbytis francoisi and Presbytis leucocephalus, with notes on the activity pattern of Presbytis leucocephalus. Folia Primatologica. Vol. 60, 83-93.
Marsh, C.W. 1987. A framework for primate conservation priorities on Asian moist tropical forests. in Primate Conservation in the Tropical Rain Forest. eds. C.W. Marsh and R.A. Mittermeier. Liss: New York.
Ratajszczak, R., Cox, R., and Ha, D.D. 1990. Report of a preliminary survey of primates in northern Vietnam. July - October 1989. World Wildlife Fund Project 3869. Unpublished report.
Rich, D. 1983. Aunting behavior among Francois's. Zoonooz. Vol. 54(3), 12-14.
Last Updated: June 20, 2007.
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