Rhesus macaque

The rhesus macaque (Macaca mulatta) is one of the best-known species of Old World monkeys. It is listed as Least Concern in the IUCN Red List of Threatened Species in view of its wide distribution, presumed large population, and its tolerance of a broad range of habitats. It is native to South, Central, and Southeast Asia and has the widest geographic range of all non-human primates, occupying a great diversity of altitudes and a great variety of habitats, from grasslands to arid and forested areas, but also close to human settlements. The rhesus macaque is brown or grey in color and has a pink face, which is bereft of fur. It has, on average, 50 vertebrae, a dorsal scapulae and a wide rib cage. Its tail averages between 20.7 and 22.9 cm (8.1 and 9.0 in). Adult males measure about 53 cm (21 in) on average and weigh about 7.7 kg (17 lb). Females are smaller, averaging 47 cm (19 in) in length and 5.3 kg (12 lb) in weight. The ratio of arm length to leg length is 89%. The rhesus macaque has a dental formula of 2.1.2.32.1.2.3 × 2 = 32 and bilophodont molar teeth. Rhesus macaques are native to India, Bangladesh, Pakistan, Nepal, Burma, Thailand, Afghanistan, Vietnam, southern China, and some neighboring areas. They have the widest geographic ranges of any non-human primate, occupying a great diversity of altitudes throughout Central, South, and Southeast Asia. Inhabiting arid, open areas, rhesus macaques may be found in grasslands, woodlands, and in mountainous regions up to 2,500 m (8,200 ft) in elevation. They are regular swimmers. Babies as young as a few days old can swim, and adults are known to swim over a half mile between islands, but are often found drowned in small groups where their drinking waters lie. Rhesus macaques are noted for their tendency to move from rural to urban areas, coming to rely on handouts or refuse from humans. They adapt well to human presence, and form larger troops in human-dominated landscapes than in forests. The southern and the northern distributional limits for rhesus and bonnet macaques, respectively, currently run parallel to each other in the western part of India, are separated by a large gap in the center, and converge on the eastern coast of the peninsula to form a distribution overlap zone. This overlap region is characterized by the presence of mixed-species troops, with pure troops of both species sometimes occurring even in close proximity to one another. The range extension of rhesus macaque – a natural process in some areas, and a direct consequence of introduction by humans in other regions – poses grave implications for the endemic and declining populations of bonnet macaques in southern India. The Thai population is locally classified as endangered. There are about 1,000 troops at Wat Tham Pha Mak Ho, Tambon Si Songkhram, Wang Saphung district, Loei province. The name 'rhesus' is reminiscent of the mythological king Rhesus of Thrace, a minor character in the Iliad. However, the French naturalist Jean-Baptiste Audebert, who applied the name to the species, stated: 'it has no meaning'. According to Zimmermann’s first description of 1780, the rhesus macaque is distributed in eastern Afghanistan, Bangladesh, Bhutan, as far east as the Brahmaputra Valley in peninsular India, Nepal, and northern Pakistan. Today, this is known as the Indian rhesus macaque M. m. mulatta, which includes the morphologically similar M. rhesus villosus, described by True in 1894, from Kashmir, and M. m. mcmahoni, described by Pocock in 1932 from Kootai, Pakistan. Several Chinese subspecies of rhesus macaques were described between 1867 and 1917. The molecular differences identified among populations, however, are alone not consistent enough to conclusively define any subspecies.