Mentawai Macaque (Macaca pagensis)

This species has cheek pouches to carry food in while it forages. The dental formula of the Mentawai macaque is 2:1:2:3 on both the upper and lower jaws (Ankel-Simons, 2000). The tail is thinly furred (Groves, 2001). This species has short cheek whiskers (Groves, 2001).

The Mentawai macaque has two subspecies, each with differing pelage colorations:
  • Macaca pagensis pagensis: The dorsal side is dark brown and the sides of the neck and the front of the shoulders are a pale ochery coloration (Groves, 2001). The legs of this subspecies are brown and the arms are reddish brown (Groves, 2001).
  • Macaca pagensis siberu: This subspecies is much darker than M. p. pagensis and has a white cheek patch (Groves, 2001).

The Mentawai macaque is found on the Mentawai Islands, which are off the coast of Sumatra, Indonesia. There are four islands of the Mentawai Island chain, North and South Pagai, Sipora, and Siberut, and this species is found on all four of them (Groves, 1996; Fuentes, 1996/1997). This species lives in primary forests and in disturbed areas (Whitten and Whitten, 1982; Fuentes, 1996/1997). The type of primary forest this species prefers is riverine coastal swamp forest (Wilson and Wilson, 1976).

The Mentawai macaque has two subspecies, each having differing ranges:
  • Macaca pagensis pagensis: This subspecies is found on North Pagai Island, South Pagai Island, and Sipora Island, Indonesia (Groves, 2001).
  • Macaca pagensis siberu: This subspecies is found on Siberut Island, Indonesia (Groves, 2001).

This species is a primarily frugivorous species (Whitten and Whitten, 1982). Whitten and Whitten (1982) found that fruits consumed include: Bhesa paniculata, Calamus sp., Litsea sebifera, Agelaea macrophylla, Arenga obtusifolia, Endospermum malaccense, Ficus sublata, Ficus vasculosa, and Syzygium fastigiatum. This species will also raid gardens for food (Tenaza, 1988). The Mentawai macaque feeds in primary and secondary forests as well as gardens and coconut groves (Fuentes, 2002; Fuentes and Olson, 1995). Group sizes range from 5 to 25 individuals (Fuentes, 2002; Fuentes and Olson, 1995). Groups will split into smaller subunits when foraging during the day (Fuentes, 2002; Fuentes and Olson, 1995; Whitten and Whitten, 1982). Mentawai macaques generally sleep in tall trees near secondary-ridge tops, such as Dipterocarpus retusus (Whitten and Whitten, 1982). No tree is used twice for sleeping, and subgroups will sometimes sleep together in the same tree (Whitten and Whitten, 1982). Humans, Homo sapiens, are the main predators of this species, mainly killing them because they raid crops and gardens (Fuentes, 2002; Fuentes and Olson, 1995; Tenaza, 1988). Whitten and Whitten (1982) suggest that the crested serpent eagles (Spilornis cheela sipora) and pythons (Python reticulatus) are predators of this species.

The Mentawai macaque is a quadrupedal species (Fleagle, 1988).

It appears that this species has a unimale social system (Whitten and Whitten, 1982). Solitary males have been seen in this species (Fuentes, 2002; Fuentes and Olson, 1995). The Mentawai macaque will form mixed-species groups with the Mentawai Island leaf-monkey, Presbytis potenziani (Fuentes, 2002).

harsh bark: This is a loud call emitted by adult males, most frequently around dawn (Whitten and Whitten, 1982). This is a high-pitched vocalizations consisting of repeated units (Watanabe, 1979; Whitten and Whitten, 1982; Abegg and Thierry, 2002). This call could function to coordinate group movements and establish the direction of movement (Whitten and Whitten, 1982).

restrained bark: This is a gruff call that is heard by individuals when they are alarmed (Whitten and Whitten, 1982).


silent bared-teeth display: This is where the mouth is opened and the lips are retracted vertically, exposing the teeth (Abegg and Thierry, 2002). This display is used to initiate affiliative interactions, which differs from other macaques, such as the pigtailed macaque (Macaca nemestrina), where the display communicates submission (Abegg and Thierry, 2002). TACTILE COMMUNICATION:

The Mentawai macaque gives birth to a single offspring.

Abegg, C. and Thierry, B. 2002. The phylogenetic status of Siberut macaques: Hints from the bared-teeth display. Primate Report. Vol. 63, 73-78.

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

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

Fuentes, A. 1996/1997. Current status and future viability for the Mentawai primates. Primate Conservation. Vol. 17, 111-116.

Fuentes, A. 2002. Monkeys, humans and politics in the Mentawai Islands: no simple solutions in a complex world. in Primate Face to Face: The Conservation Implications of Human-nonhuman Primate Interconnections. eds. A. Fuentes and L.D. Wolfe. Cambridge University Press: Cambridge, U.K.

Fuentes, A. and Olson, M. 1995. Preliminary observations and status of the Pagai macaque. Asian Primates. Vol. 4(4), 1-4.

Groves, C. 1996. The nomenclature of the Tanzanian mangabey and the Siberut macaque. Australian Primatology. Vol. 10(4), 2-5.

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

Tenaza, R.R. 1988. Status of primates in the Pagai Islands, Indonesia: A progress report. Primate Conservation. Vol. 9, 146-149.

Watanabe, K. 1979. Some observations of Mentawai pigtail macaques, Macaca nemestrina pagensis, on Siberut Island, West Sumatra, Indonesia. Report of Overseas Scientific Survey in 1976-1978. 86-92.

Whitten, A.J. and Whitten, J.E.J. 1982. Preliminary observations of the Mentawai macaque on Siberut Island, Indonesia. International Journal of Primatology. Vol. 3(4), 445-459.

Wilson, C.C. and Wilson, W.L. 1976. Behavioral and morphological variation among primate populations in Sumatra. Yearbook of Physical Anthropology. Vol. 20, 207-233.

Last Updated: November 26, 2003.
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