Scientific Name: Macaca mulatta
IUCN Red List Status: Least Concern
Habitat: Rhesus macaques are Asian, Old World monkeys. They are the second most widespread primate species in the world after humans. Rhesus monkeys are widely distributed in south, southeast, and east Asia. Their range includes Afghanistan, Nepal, Thailand, India, along with other countries. Their range is so broad, allowing them to occupy many different types of habitats. They are found in both tropical and temperate habitats, including semi-desert, dry deciduous, mixed deciduous, and bamboo forests. Rhesus macaques may also be found in tropical forests and mangrove swamps.
There is also a population of rhesus monkeys found in Florida. This population arose in the 1930s when the manager of a boat tour operation released six monkeys onto an island with the hopes that it would increase tourism for his business. But, rhesus macaques are impressive swimmers; they made their way to the surrounding forests on the mainland, where their population grew rapidly. In 1948, the owner of Silver Springs Park, the facility that owned the original boat tours, released six more macaques on the island to boost revenue. Since the initial release in 1938, the rhesus macaque population in Florida has increased to nearly 400 in numbers.
Territoriality: Rhesus macaques are social animals, who typically live in large multimale troops. These troops can range in size from 8-85 individuals. The troop is essentially a closed society, and the members will react very aggressively to unfamiliar monkeys. Troops can be divided into subgroups based on the female family line. Rhesus macaques will emit “shrill barks,” or alarm calls, in threatening situations. These barks consist of a single, loud, high-pitched sound. During aggressive interactions, vocalizations may include screens, screams, squeaks, pant threats, growls, and barks.
Rhesus macaques are well adapted to coexisting with humans because of their adaptability; their home range varies. Macaques that live near urbanization are adapted to surviving in smaller, more developed areas.
In the Wild: 30-36 years
In Captivity: 27-40 years
Unknown across Asia, Silver Springs State Park in Florida estimated 190
Weight: 12-17 pounds
Length: 2- 3ft including tail
Rhesus macaques can be brown or gray, their faces and rumps are pink with no fur, and tails are half the length of their bodies. Although they have tails, they are not prehensile and therefore not used too often for movement. The species is sexually dimorphic, where males are larger. They are quadrupedal or walk on all fours, and depending on the habitat; they may be predominantly arboreal or terrestrial.
Because of their closeness to humans, anatomically and physiologically, the rhesus macaques have been researched on for human and animal health-related topics. The development of rabies, smallpox, and polio vaccines; discovery of rhesus factor in the blood; the creation of drugs to manage HIV/AIDS; understanding the female reproductive cycle and development of the embryo; the propagation of embryonic stem cells; and a number of behavioral discoveries would not have been possible without the use of rhesus macaques in research. Unfortunately, because they were so useful in medical research, they were captured at an alarming rate. Often in the 1960s, over 50,000 juvenile rhesus macaques were trapped and shipped from India per year. This crippled the population growth of the species. It wasn’t until 1978 when a total ban on their export was established that the population began to grow.
Gestation period: 5.5 months
Litter Size: 1 offspring per year
Rhesus macaques will use grooming behavior during their mating activities. Mating typically occurs in late summer or early fall and lasts 4-5 months. When the females are in estrus, the males and females will form a temporary social bond called consortship. These consortships may last from several hours to a few days. Dominant males will guard the females and prevent other males from approaching her. Females will give birth beginning in late winter into the early summer months.
Rhesus monkeys have a long period of infant dependency and an extended mother-infant relationship. During the first year of life, the time spent interacting with the mother declines, but half will still nurse past one year of age and spend time in contact with her. After the first year, female infants continue to maintain a close relationship with their mother, whereas males join playgroups. Female rhesus macaques will typically remain in with the group they are born into, and males will leave before they reach sexual maturity.
Diet and Hunting Behaviors
Rhesus macaques are omnivores who have an extremely varied diet. Their diet includes roots, seeds, fruit, and bark. These monkeys may also consume insects and have been known to eat bird eggs. Rhesus macaques spend nearly 50% of their time moving to food sites and foraging for food. They also raid crops. When high-quality, rare food is found, “warbles,” “harmonic arches,” and “chirps” are heard.
Threats and Conservation
The problems of habitat destruction do not seem to affect rhesus macaques like it does other primates, as they are well adapted to life near humans and can thrive in highly disturbed environments. The population of rhesus macaques in India is increasing. This increase is not necessarily positive; in the areas where the animal comes in contact with humans, they are thought to be menaces. They will threaten or bite children and the elderly, steal food from people, raid crops, and damage property. All of these destructive behaviors can lead to decreased tolerance and, in some areas, persecution. Human-animal conflicts will only increase if habitat destruction does not stop and will likely force government control measures, such as trapping and relocation. Forest-dwelling rhesus macaques are threatened because of cattle grazing, illicit timber and fuelwood harvesting, and settlement pressure.
In some areas in India, because of their fiendish behavior, rhesus macaques are subjected to stoning, trapping, and shooting. A survey completed in one region of India showed that over 95% of locals felt harassed by the rhesus macaques due to bites, stealing of household items, or other nefarious activities performed by the monkeys. Their behaviors have lowered the public opinions of macaques across their region, in turn reducing the associated conservation ethic. If this ethic is lost, it will be difficult to rekindle in the future if the population stops growing or decreases.
The root cause of the conflict between humans and rhesus monkeys is the destruction of the monkey’s natural habitat, which forces the species closer to humans. Although they may do well in urbanized areas, the rhesus macaques who live in forested areas are usually healthier, eat a better diet, and are overall in better conditions than urban macaques. Restoring their natural habitat may decrease conflict, but they will most likely move back due to increased food availability near humans. Translocation of a large population of the species is one option to remove the animals who have come dependent on human sources of food. Another option would be to use deterrent fencing or other protective measures around gardens and crops to prevent crop-raiding. Monkey-proof containers can store household items, food, and prevent local monkeys from scavenging for food. Long term management will be necessary to conserve healthy populations of the species and prevent persecution by humans.