Stump-tailed Macaque

Macaca arctoides

Infant stump-tail macaques are white.

Information supplied by:  The Pictorial Guide to The Living Primates

Taxonomy: Monotypic.  The name was changed from M. speciosa in 1976.

Distinguishing Characteristics:  Stump-tailed macaques are dark brown, with a short, nearly hairless tail.  The face is hairless and mottled with varying amounts of black and red skin.

Physical Characteristics:  Head and body length: Female: 485-585mm (19.1-23.0 in), Male: 517-650mm (20.4-25.6 in), Tail length: Female: 14.5 - 69mm (0.6-2.7in), Male: 3.2-12.5mm (0.1-0.5in), Weight, Female: 7.5-9.1 kg (16.5-20.1 lb), Male: 9.9-10.2kg (21.8 - 22.5 lb).  Intermembral index: 98.  Adult brain weight: 104.1 g (3.7 oz).

Habitat:  Lowland forest, monsoon forest, dry forest, and montane forest up to 2000m (65ft).  These macaques prefer dense forest and are occasionally found near human settlements and temples.

Diet:  Fruit, seeds, young leaves, flowers, buds, and animal prey, including insects, birds, and eggs.

Life History infant: 6-12 mo.  Weaning: 9-18 mo, Juvenile: 12-48 mo.  Sub adult: 48-96 mo.  Sexual Maturity: NA  Estrus cycle: 29d.   Gestation: 178.2d (`166-185).  Age ist birth: 45.6-56.4 mo.  Birth Interval: 19mo (12-24).  Life span: 30y.  Females have no visual sign of estrus.   Neonates are creamy white.

Locomotion: Quadrupedal.

Social Structure:  Multimale-mutifemale groups.   Matrilineal hierarchies are very strong.  Group size: 5-40.  Home range: NA  Day range: 400-3000m (1312-9843ft).

Behavior:  Diurnal, arboreal, and terrestrial.   Stump-tailed macaques travel on the forest floor and along the banks of streams.   They do not swim.  The have been the subject of many captive behavioral studies but few field studies.  After a conflict, they have a ritual reconciliation behavior in which the subordinate presents its hindquarters to the dominant, which clasps the presenter by the rump.  The eases the tension between individuals.  Grins, teeth chattering, and lip-smacking are other signs of submission.  The subordinate may also offer a hand for a mock bite.  The dominant animal may present to a low-ranking individual to reassure or pacify it.  Grooming is a form of social interaction that promotes appeasement and group cohesion.  These macaques may groom for a few seconds to more than an hour.  In a captive study, wounded individuals were groomed more than usual.  The dominant male stops female fights and protects infants.   In a captive study, 66% of all social behavior involved touching and huddling.   Some 50% of the agonistic behavior toward mating pairs was directed by adult females.  The tail position indicates an individual's intentions: tail down means submission or fright; tail curled up indicates excitement; tail straight up is an assertion of dominance.  The teeth-chattering face is a greeting or appeasement signal.  When attacked by a high-ranking animal, a stump tail may redirect its aggression by attacking a nearby subordinate.  In Assam these monkeys are feared and reputed to attack people if they are disturbed.

Mating:  Dominant males copulate with high-ranking females throughout their estrus cycles.  Mating lasts 12-20 minutes, after which partners remain attached and are often harassed by other members of the group.  Of all the observed mating, 92% had some form of harassment.  High-ranking males are the most likely to be harassed, usually by adult females and juvenile males and females.  When low-ranking males mate, they are often interrupted by the dominant male; to avoid interruption, they mate while he is mating with another female.  A male can copulate 10 times a day.  Males and females make an orgasm face.  A crescent-shaped vaginal plug is formed by semen.  The male's penis fits lock-and-key with the female's specialized reproductive tract and may function as a reproductive isolation method.

Vocalizations:  17 graded calls.  The most common vocalization is a coo used when approaching other group members to avoid aggression and initiate grooming or other friendly interactions.  Southern China and Southeast Asia.