PHYSICAL DESCRIPTION: Male height 21-25 in. Weight 15-22 lbs. Female height IS- 21in. Weight 9-20 lbs. Coat: short, coarse brown to yellow fur. Reddish face is common to all macaques. Rhesus Macaques have a cheek pouch on the inside of each cheek. Non- prehensile WI. Longevity: In captivity 21 years of age.
GEOGRAPHIC LOCATION: Native to southern Asia, (Eastern Afghanistan through Northern India and Nepal). Also been introduced into the West Indies on Cayo Santiago, A small island off the eastern tip of Puerto Rico.
ECOLOGY: Essentially frugivore. Primary and Secondary, inland and coastal, lowland and highland forests. No specific habitat requirements but prefers lowland forests. Active from dusk to dawn. Traveling 9-10 hours a day. Home range: 60-70 ha. Day range: 825-1140 in. Population density: 126/km squared.
DIET: Ripe fruits (74%), invertebrate animals (12%), plants and vertebrates (14%)
SOCIAL ORGANIZATION: Group size ranges from small to as large as 236 members, but the average size is 9-58 members. Groups contain several adult males, 2-3 times as many adult females, and an equal number of offspring. Dominance network highly dependent on material ranks. Adolescent males leave the group to form new groups while females stay with the original group throughout their lives. Male dominance is directly related to reproductive success. Males are aggressive toward other males and females. The females benefit from having relations with a high ranking male. Females also receive protection along matrilineal lines. Vocalization highly important to group.
INTELLIGENCE: Highly intelligent and lively, may become bad-tempered as an adult. Studies have been done to test the memory and leaming capabilities.
REPRODUCTION: Mating occurs in September and October. Males sexually mature at the age of 4 and a half years and females at he age of 3 and a half years. Gestation averages about 164 days of 5.5 months. Birth occurs 7 months after mating. One baby is born twins are very rare usually weighing around 16 oz.. During females ' menstrual cycle there is usually a visible change in the genital area, a red coloration. Males' testes become enlarged and the naked skin of the posterior takes on a redder color also.
PARENTAL CARE: Mothers nurse their young for 7-14 months. Like human babies, Rhesus babies seek physical contact with their mothers. This is needed for normal emotional development of infant monkeys. Males leave their group and migrate to a new one at a young age for mating purposes.
TOPICS OF SPECIAL INTEREST: Rhesus macaques were used as early space travelers to test the physiological effects of space. The RH blood factor, present in man but first identified in the rhesus monkey, is named for it. Psychological testing shows their ability to use symbols.
BIBLIOGRAPHIC SOURCES: Colliers Encyclopedia. 1996 p.32-33
Encyclopedia Americana, Grolier Incorp., Danbury, Connecticut, Vol. 23, 1992, p.465 World Book Encyclopedia 1995 p.291
Fa, John and Donald Lindberg (editors), Evolution and Ecology of Macaque Societies, 1996. Wolfheim, Jaclyn, Primates of the World, 1983, p. 491
Rawlings, Richard, and Matt Kessler, The Cayo Santiago Macaque, SUNY Press, 1986, pp.3,5
Grzimek's Encyclopedia, Mammals Vol. 2 p.213-216, & 234
Loy, J.; K. Loy; G. Keifer; C. Conway; The Behavior of Gonadectomized Rhesus monkeys.84