The common name, rhesus monkey, is responsible for the naming of the hereditary blood antigen Rh-factor that was discovered on their red blood cells in 1940. Rh-factor is also found in humans. The mixing of Rh blood with non-Rh blood during blood transfusions or the later stages of pregnancy can result in potentially dangerous defense reactions.
(Nowak 1991)
The name "rhesus" comes from Greek, Rhesos, the King of Thrace who assisted Priam at Troy. Audebert, the person who applied the name to the species, stated that it had no meaning.
(Jaeger 1972)
Communication in all monkeys involves a variety of visual signals (such as body postures and facial expression), tactile communication (such as grooming, playing and fighting), vocalizations, and scent cues.
Communication Channels: visual ; tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
IUCN considers this species Lower risk/ near threatened.
US Federal List: no special status
CITES: appendix ii
IUCN Red List of Threatened Species: least concern
In India, rhesus monkeys do significant damage to crops and gardens in many areas. Because they are viewed as sacred animals by Hindus, often little is done to stop them from stealing crops.
As is true of most nonhuman primates, there is a high risk that they could carry diseases which affect humans.
(Nowak, 1991; Parker, 1990)
Negative Impacts: injures humans (bites or stings); crop pest
Macaca mulatta is a popular zoo animal because of its innate curiosity and active lifestyle. These monkeys are also used extensively for research. They are especially useful in biological, medicinal, and psychological research. Macaca mulatta is most often used in psychological research when the emphasis is on perception, learning, or behavior.
(Nowak, 1991; Parker, 1990)
Positive Impacts: source of medicine or drug ; research and education
The role of these animals in their ecosystems has not been fully described. Because of their frugivory, rhesus monkeys may help to disperse seeds. As a prey species, they may affect predator populations.
The dietary habits of rhesus monkeys can vary greatly depending upon where they live. Macaca mulatta is omnivorous, and often eat roots, herbs, fruits, insects, crops, and small animals. The diet can also vary with the season. For example, rhesus that live in the mountain forests of northern Pakistan feed primarily on clovers during the summer, but during winter when snow covers the ground they are forced to switch to foods with lower nutritional values and higher fiber contents, such as pine needles and oak leaves. These monkeys seem to choose their environments carefully with respect to food resources. Even when they are forced to switch to lower quality food sources during the winter months they do not exhibit higher mortality rates, although they may lose a considerable percentage of their body weight.
(Macdonald, 1984; Nowak, 1991; Parker, 1990)
Animal Foods: birds; mammals; amphibians; reptiles; insects
Plant Foods: leaves; roots and tubers; fruit
Primary Diet: omnivore
Populations of rhesus monkeys (Macaca mulatta) are most commonly found in western Afghanistan, through India to northern Thailand. This species was abundant historically in southern China and Tibet, but humans have caused drastic decline of populations in these areas over the last sixty years. Because M. mulatta is often used for research, today populations are kept in captivity world wide.
(Nowak, 1991; Parker, 1990; Wilson and Reeder, 1993)
Biogeographic Regions: palearctic (Native ); oriental (Native )
Macaca mulatta lives in a wide range of habitats, and shows a great deal of adaptability. Some populations live in flatlands, while others, in northern India and Pakistan, live in the Himalayas at elevations up to 3,000 m. These primates are able to aclimate to a variety of climatic extremes, from the hot, dry temperatures found in deserts, to cold winter temperatures which fall to well below the freezing point.
In addition to living in the wilderness, some populations of M. mulatta have become accustomed to living alongside humans. Occasionally, small groups can be found living in the densely populated urban areas of northern India. Groups of rhesus monkeys that become used to living in areas occupied by people usually search out other human-populated areas if people attempt to relocate them away from civilization.
(Nowak, 1991; Parker, 1990)
Range elevation: 3,000 (high) m.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland ; forest ; mountains
Other Habitat Features: urban ; suburban ; agricultural
Rhesus monkeys can live up to 30 years.
Range lifespan
Status: wild: 30 (high) hours.
Range lifespan
Status: captivity: 30 (high) hours.
Average lifespan
Status: captivity: 36.0 years.
Average lifespan
Sex: female
Status: captivity: 23.0 years.
Average lifespan
Status: captivity: 35.0 years.
Average lifespan
Status: captivity: 26.0 years.
Average lifespan
Status: wild: 30.0 years.
These smallish monkeys have grizzled-brown fur dorsally, with the fur on the ventrum being slightly lighter in color. The hair is short on the head. The face and buttocks of adults are red.
Length varies in this species, ranging between 45 and 64 cm. The tail adds an additional 19 to 32 cm to the total length. Males are somewhat heavier than females, weighing between 6.5 and 12 kg. Females weigh a mere 5.5 kg on average.
Range mass: 4 to 12 kg.
Range length: 45 to 64 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Primates are often wary of potential predators. It is likey that large carnivores, raptors, and snakes could prey upon these macaques.
Although rhesus monkeys show mate preferences, in general they are highly promiscuous. As they live in multi-male, multifemale groups, there are ample opportunities for individuals to copulate with multiple partners.
Female rhesus monkeys have a sexual cycle of 29 days. They are receptive to copulation for between 8 and 11 days during that cycle. To solicit copulations, females present their hindquarters to males. The skin of the perineal region becomes redded when the female is in estrus, and aliphatic acids are present, proving a potential chemical cue to their state of fertility.
Rhesus monkeys are serial mounters, meaning that males mount a female multiple times before ejaculating.
Males attract mates either by having high dominance status within the social group, or sometimes by being friendly (grooming, carrying infants, etc) to females.
Mating System: polygynandrous (promiscuous)
The breeding season varies widely amongst populations. Populations that live in areas where the winters are cold mate in the fall so that the young are born in the spring. Macaca mulatta that live where seasonal changes are less pronounced have less well-defined mating seasons.
The gestation period is around 165 days, and almost all pregnancies results in birth of a single young. When kept under uniform conditions in captivity, females maintain a steady estrus cycle of 26 to 28 days.
Unlike many primate species, the estrus cycle of M. mulatta is not accompanied by major changes in the females' genital region. There is only minor swelling and redness around the genital area.
In populations that have distinct breeding seasons, testes swell to almost double their normal size during the breeding season. The disproportionately large testicles of male rhesus monkeys, and the increase in size of their testicles during the breeding season, is probably related to the number of times a male can copulate over a short period of time.
(Buscovitch, 1993; Nowak, 1991; Parker, 1990)
Newborn macaques weigh between 400 and 500g. They nurse from their mother for about 1 year. Although young macaques typically cling to their mother's ventrum for the first few weeks of life, as their ability to keep themselves upright improves, they ride upon the mother's back. Females reach nreproductive maturity at 2.5 to 3 years of age. Males take longer to complete the transition to adulthood, reaching sexual maturity at 4.5 to 7 years of age. (Nowak, 1991)
Breeding interval: Females are capable of producing one young per year under good conditions.
Breeding season: Populations that live in areas where the winters are cold mate in the fall; those that live where seasonal changes are less pronounced have less well defined mating seasons
Average number of offspring: 1.
Range gestation period: 133 to 200 days.
Average gestation period: 165 days.
Average weaning age: 12 months.
Range age at sexual or reproductive maturity (female): 2.5 to 4 years.
Range age at sexual or reproductive maturity (male): 4.5 to 7 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous ; post-partum estrous
Average birth mass: 464 g.
Average number of offspring: 1.
As is common to most primates, the bulk of parental care falls to females. Mothers provide their young with protection, nutrition, grooming, and social experience from birth until independence.
The role of males in parental care is somewhat confusing. Because social groups contain multiple males, and because females mate with many of these males, there is no certainty of paternity, so males don't even know which young are theirs. There may be some care given to young by close male friends of the mother. These males may be more likely to have sired the offspring.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Protecting: Female); post-independence association with parents; extended period of juvenile learning; inherits maternal/paternal territory; maternal position in the dominance hierarchy affects status of young
