Colobus angolensis
Angolan colobus

Angolan colobus monkeys are found from eastern Nigeria through Cameroon, eastern Gabon, northern Congo, the central African Republic, northeastern Zaire, Uganda, Ruanda, Ethiopia, Kenya, and northern Tanzania (Grzimek, 1990). (Grzimek, 1988)

Angolan colobus monkeys are found in various habitat types such as gallery, montane, lowland, and bamboo forests. They are also found in savannas and swamp lands. This species inhabits primary and secondary lowland to montane forest up to 3000m (Rowe, 1996; Grzimek, 1990).

Colobus monkeys are medium-sized, arboreal monkeys with slender bodies and long tails. The five recognized species of Colobus share the following characteristics: a reduced thumb, prominent rump callosities, and a complex stomach which aids in the digestion of cellulose. Angolan colobus monkeys have long, silky hair. They are black with a white brow band, cheeks, and throat. They have long-haired white epaulettes on the shoulders and the lower half of the tail is white. The tail length is 706 mm for females and 829 mm for males and head and body length ranges from 490 to 680 mm. Mass varies between 6 and 11.4 kg, with males slightly larger than females. Young are born completely white and begin changing to their adult pelage at about three months of age (Rowe, 1996; Grzimek, 1990; Wisconsin Primate Research Center, 2000). (Grzimek, 1988; Rowe, 1996; Wisconsin Primate Research Center, April 12, 2000)

Colobus angolensis is polygynous. Dominant adult males control reproductive access to the females within their family group. Younger males from within the group or from other groups may periodically replace the dominant male. Females of the family group mate with the dominant male.

In most Angolan colobus social groups there is one adult male present with about 2 to 6 females. Larger groups generally have more than one resident male. A behavior called presenting is performed by the female to communicate to the male that she is ready for copulation (Estes, 1991; Nowak, 1999). The gestation period ranges from 147 to 178 days and a single offspring is generally born, though twins are possible. In this species, the infants are born all white and start changing color at about 3 months old. Young are not weaned until they are about 15 months of age. Males reach sexual maturity in four years, females in about two years (Grzimek, 1990). (Estes, 1991; Grzimek, 1988; Nowak, 1999)

Young Colobus monkeys are cared for by their mothers and by other members of the social group. The infants are weaned in about 15 months.

Angolan colobus monkeys can live for 20 years in the wild and up to 30 years in captivity (Grzimek 1990).

Angolan colobus monkeys are diurnal and arboreal. They occasionally come to the ground near streams to eat herbaceous vegetation but prefer to remain higher in the canopy. They are the most arboreal of all African monkeys. These colobus monkeys live in troops of up to 25 individuals, although temporary gatherings of over 300 have been observed. They typically live in relatively small social groups of one adult male and normally two to six females with offspring. Young males in the group are forced to leave before they reach breeding age but may also challenge the dominant male for control of the females. When a troop is threatened by a predator, the male jumps and roars until the rest of the troop has fled (Rowe 1996, Fimbel 2001). Groups defend a relatively small core home range from other troups of Colobus monkeys. Morning roaring contests between dominant males may help to maintain group spacing (Nowak, 1999).

Angolan colobus monkeys are primarily folivorivous, although they also feed on stems, bark, flowers, buds, shoots, fruits, some aquatic plants' fruits and insects. They are also known to eat clay from termite mounds. In many parts of their range, young leaves of the hackberry tree are the food of choice. They can eat up to two to three kilograms of leaves a day and normally feed in the morning and evening (Rowe 1996, Estes 1991).

Angolan colobus monkeys are diurnal and highly arboreal, which may help avoid predators that feed at night. They are also able to avoid predators by maneuvering quickly through the trees and by group members joining together to defend themselves (Sanders 2000, Grzimek 1990).

This species provides food for some large predators, such as eagles and large cats. They may disperse seeds of the fruits they eat.

Angolan colobus monkeys benefit the people of Africa by providing them with meat and skins. They also attract ecotourism activities and have been used in research (Von Hippel 2000).

Although all primate species may harbor diseases that can be passed to humans, Angolan colobus monkeys do not have significant negative impacts on humans.

Angolan colobus monkeys are not considered endangered and may be fairly abundant in parts of their range. However, they are vulnerable to habitat destruction and have suffered extensively by hunting for bushmeat and skins, especially in highly populated areas. Populations are declining fairly rapidly in some areas such as the Kakamega forest in Kenya (Von Hippel 2000, Grzimek 1988).

Colobus is derived from a word meaning "mutilated one" because, unlike other monkeys, Colobus monkeys lack thumbs.