Crab-eating Macaque (Macaca fascicularis)

This species has cheek pouches to carry food in while it forages. The average body mass for an adult male crab-eating macaque is around 6 kilograms, and for the females it is around 4 kilograms. The tail on this species is quite long.

The crab-eating macaque is found in the countries of Brunei, Burma, Cambodia, Indonesia, Laos, Malaysia, Philippines, Thailand, and Vietnam. This species is found in a variety of forest habitats throughout its range, it especially prefers edge habitats.

The crab-eating macaque is a frugivorous species, but will also eat leaves, insects, grasses, seeds, flowers, buds, shoots, gum, sap, and bark. This species will also raid crops and eat the food such as rice and taro plants. It will also forage for plant species located near water (Richard, 1985). The average group size for the crab-eating macaque is 30 individuals. This species is mostly arboreal, spending much of its time in the forest canopy, but it occasionally comes down to the ground. This is a diurnal species.

The crab-eating macaque is a quadrupedal species (Fleagle, 1988). This species sometimes swims in lagoons or rivers (Richard, 1985).

The crab-eating macaque has a multimale-multifemale social system. Females remain in their natal group with the onset of maturity, but males will disperse shortly before adolescence. There is a hierarchical system amongst group members based upon the matriline. The mating system for the crab-eating macaque is a promiscuous system, but most of the mating is done by an alpha male. Males will sometimes form affiliations with same age males from their natal group. Both males and females are aggressive during intergroup encounters (Angst, 1975).


fear grimace: The lips are retracted so that the teeth are shown; the teeth are clenched together (Estes, 1991). This display functions as an appeasement signal to reduce aggression in aggressive encounters (Estes, 1991).

staring with open mouth: This is the stare accompanied by the mouth being open but the teeth are covered (Estes, 1991). This is a threat expression (Estes, 1991).


The crab-eating macaque gives birth to a single offspring.

Angst, W. 1975> Basic Data and Concepts in the Social Organization of Macaca fascicularis. in Primate Behavior, vol. 4, ed. L.A. Rosenblum. Academic Press.

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

Estes, R.D. 1991. The Behavior Guide to African Mammals. University of California Press.

Fleagle, John G. 1988. Primate Adaptation and Evolution. Academic Press.

Richard, A.F. 1985. Sympatry, Competition, and the Niche. In Primates in Nature, ed. A.F. Richard. W.H. Freeman and Co.

Last Updated: October 9, 2003.
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