both homosexual and heterosexual mounting, but it appears that they generally have more different male partners than female ones. Some males participate very little in homosexual activity (accounting for about 10 percent of the same-sex mountings in a population), while others may be involved in more than half of all homosexual mounts. A similar variation occurs with respect to their heterosexual participation. However, males that are the least active heterosexually are not necessarily the most active homosexually: in many cases, those males that participate in a large number of homosexual mountings also have a large number of heterosexual mountings. No quantitative information on sexual orientation is available for Crab-eaters; however, observations in captivity indicate that males engage in both homosexual and heterosexual copulation, sometimes alternating relatively frequently between the two. Furthermore, males that are “bonded” to one another show a preference for their partner that even survives separation and intervening heterosexual activity. If such males are separated from one another, they rush to embrace each other on being reunited, resuming their sexual relationship where they left off.
Nonreproductive and Alternative Heterosexualities
As noted above, heterosexual matings in Crab-eating Macaques are not always consensual: about 19 percent of such mounts are forced by the male on the female. Furthermore, male Crab-eaters sometimes severely attack females with small babies and also occasionally kill those infants to gain sexual and breeding access to the female. Both Bonnets and Crab-eaters participate in a range of nonprocreative sexual behaviors. Among Crab-eaters, females copulate during pregnancy (though usually not during the first two to three weeks), while more than half of male-female copulations do not involve ejaculation. In both species, females have multiple male partners and copulations—during one six-month period, for example, each female Crab-eater mated an average of 45 times, with some copulating more than 110 times. Female Bonnets may mate with up to three different males in succession, and females also sometimes mount males (REVERSE mounting). Male Bonnet Macaques may also manually penetrate females, inserting a finger and then licking or smelling it. Unlike in a number of other primates, in Bonnets this behavior does not appear to be simply a way of testing the sexual receptivity of the female. Both male and female Bonnets also masturbate, females sometimes employing innovative techniques (such as using objects or pulling their tail between their legs and using it to rub their labia while making pelvic thrusting movements). Crab- eating Macaques engage in an interesting form of “infidelity”: heterosexual mating typically occurs within a short- term bond or consortship. However, nearly 20 percent of all copulations in some populations are nonmonogamous: half of all females and almost three-quarters of the males “steal” matings with other partners during a consortship, but return to their original partner afterward. The social system of Bonnet Macaques may entail considerable inbreeding, and incestuous mother-son matings that produce viable offspring do occur.
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Emory, G. R., and S. J. Harris (1978) “On the Directional Orientation of Female Presents in
*Hamilton, G. V. (1914) “A Study of Sexual Tendencies in Monkeys and Baboons.”
*Kaufman, I. C., and L. A. Rosenblum (1966) “A Behavioral Taxonomy for
*Makwana, S. C. (1980) “Observations on Population and Behavior of the Bonnet Monkey,
Moore, J., and R. Ali (1984) “Are Dispersal and Inbreeding Avoidance Related?”
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*Poirier, F. E., and E. O. Smith (1974) “The Crab-Eating Macaques (
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*———(1968) “The Expressive Movements of the Bonnet Macaque.”
*Rasmussen, D. R. (1984) “Functional Alterations in the Social Organization of Bonnet Macaques (
*Silk, J. B. (1994) “Social Relationships of Male Bonnet Macaques: Male Bonding in a Matrilineal Society.”
———(1993) “Does Participation in Coalitions Influence Dominance Relationships Among Male Bonnet Macaques?”
Sinha, A. (1997) “Complex Tool Manufacture by a Wild Bonnet Macaque,
*Simonds, P. E. (1996) Personal communication.
*———(1965) “The Bonnet Macaque in South India.” In I. DeVore, ed.,
*Sugiyama, Y. (1971) “Characteristics of the Social Life of Bonnet Macaques (
*Thompson, N. S. (1969) “The Motivations Underlying Social Structure in
*———(1967) “Some Variables Affecting the Behavior of Irus Macaques in Dyadic Encounters.”
PIG-TAILED MACAQUE
IDENTIFICATION: A medium-sized monkey (up to 30 pounds in males) with olive-brown fur and a short, curly, nearly naked tail. DISTRIBUTION: Southeast Asia from Burma to Sumatra; vulnerable. HABITAT: Forests. STUDY AREAS: Near Mt. Kerinci, West Sumatra, Indonesia, subspecies
CRESTED BLACK MACAQUE
IDENTIFICATION: An entirely black monkey with a striking crest, long muzzle, high cheek and brow ridges, and a short tail. DISTRIBUTION: Sulawesi, Indonesia; endangered. HABITAT: Tropical forest. STUDY AREAS: Tangkoko-DuaSudara Nature Reserve, North Sulawesi, Indonesia; Oregon and Yerkes Regional Primate Research Centers; Woodland Park Zoological Gardens, Seattle, Washington.
Social Organization
Both of these species live in cosexual groups, containing 15–40 individuals in Pigtails and up to 40–90 individuals in Crested Black Macaques. Pig-tailed groups are matrilineal clans, in which females remain in their home (natal) group while males emigrate on reaching maturity. The heterosexual mating system is promiscuous: both
