Colobus guereza
guereza

Colobus guereza is found in diverse regions of equatorial Africa. This species is found in the lowland tropical rainforest to the upper reaches of the Montane forests of the upper Donga river and tributaries, as well as Acacia-dominated riverine galleries and evergreen thicket forests. Guerezas are also found in the equatorial areas of Africa including Nigeria, east and west of the Niger river, and locally distributed in relic forests north of the rainforest zone. They are also found along the Donga river, Gashaka, Ngelnyaki, Cameroon, Ethiopia, Gojjam, Kulla, Kenya, Uganda, Tanzania, N Congo, E Gabon, Central African Republic, NE Zaire, W Kenya, NW Rwanda, and S Sudan.

(Bateman, 1984; Grzimek, 1988; Happold, 1987; Honacki, 1982; Kingdon, 1987; MacDonald, 1984; Nowak, 1991)

Guerezas live in forest, woodlands, or wooded grasslands. They can also survive in dry, moist, or riparian forests that are either in lowlands or up to 3,300 m. They are most abundant in secondary forests or along rivers. They tend to live in the lower part of the trees if their area does not overlap with that of any other group of monkeys. When trees are not densely spaced, guerezas feed and travel on the ground.

(Bateman, 1984; Grzimek, 1988; Happold, 1987; MacDonald, 1995; Nowak, 1991)

Colobus guereza is a heavy bodied animal with a long tail. The head and body length is 45 to 72 cm and the tail length is 52 to 100 cm. Guerezas are slightly sexually dimorphic in that the males can weigh up to 1.19 times more than females. Guerezas have only four digits on each hand; the thumb is absent or represented by a small phalangeal tubercle that sometimes bears a nail. The loss of the thumb may be an adaptation for quick movements through the trees.

Members of the genus Colobus, which are in the subfamily Colobinae, are distinguished from members of the other subfamily, Cercopithecinae, by the absence of cheek pouches and the presence of prominent ischial callosities that are separate in females and contiguous in males.

The stomach of C. guereza is complex. It is subdivided by a partition into 2 subregions. The upper region contains a neutral medium, which is necessary for the fermentation of foliage by anaerobic bacteria. The black and white monkeys' large salivary glands provide a buffer fluid between the two regions of the stomach.

The coloration of fur is distinctly black and white. The face is gray and has no fur. The coat is glossy black, and the face and callosities are surrounded by white. A U-shaped white mantle of varying length is found on the sides. The outside of the thigh is variably whitish, and the tail is either a whitish or yellowish color from tip to base. There is also a large white tuft at the end of the tail.

The skull is prognathous, that is, the lower jaw projects beyond the upper. The orbits are relatively small and oval with narrow superciliary ridges. A postorbital bar forms a plate on the side of the skull separating the orbit from the temporal fossa. The nostrils are more or less lengthened by an extension of nasal skin, and the nose nearly touches the mouth.

The molar teeth have high pointed cusps, and the inside of the upper molars and the outside of the lower molars are slightly convexly buttressed. The enamel on the inside of the lower incisors is thick, and there is a lateral process on the lower second incisor.

The young of the C. guereza do not share the black and white coloration, but instead have pure white fur for the first weeks of their life.

(Bateman, 1984; Grzimek, 1972; Grzimek, 1988; Happold, 1987; Honacki, 1982; Kingdon, 1987; MacDonald, 1984; Nowak, 1991)

A member of the related species Colobus polykomos is reported to have lived 23.5 years in captivity. The lifespan of C. guereza is similar, throught to be about 29 years in captivity and about 20 years in the wild.

(Bateman, 1984; Grzimek, 1988; Nowak, 1991)

Guerezas are generally diurnal. They are highly arboreal residents of deep forest. However, when the trees are not densely packed, guerezas will feed and travel on the ground.

Guerezas live in sexually mixed groups averaging 8 to 15 individuals, with usually only one fully adult male and three or four reproducing females, adolescents and infants. Sometimes several males are present in mixed groups, but only temporarily. The fixed core of the mixed group consists of the females, who remain in the group of their birth for life. These females are thought to be close relatives that display their friendly intragroup relationships, marked by mutual grooming and well-developed "infant transfer." This latter phenomenon consists of an infant being handled by several females soon after birth and carried as far as 25 m from its mother. A mother may even suckle the infant of another female and her own simultaneously.

Black and white colobus monkeys spend most of their time sitting in the tops of trees; and they take turns sleeping at night so that at least one individual is awake at all times to watch for predators.

Unlike females, young males leave the group of their birth before they are fully mature. The adolescent guereza males leave their birth group either voluntarily or due to force from the adult male of the birth group. Upon leaving their natal group, young males lead a solitary life or temporarily associate with other solitary males. Some black and white monkey males eventually take over their own harem and create a new group.

There is no true leader of a group, but strong males usually take leadership roles. There are definite indications of infanticide in consequence of the threat of male replacements within mixed groups.

Intergroup relationships are not friendly among mixed groups of guerezas, which live in well-defined territories of about 32 to 40 acres. Territories may overlap marginally; they are vigorously defended by males with leaps and cries, hand-to-hand communication, roars, and occasional chasing and fighting. Additionally, displays of the white fringe fur flapping up and down serve as warning to other monkeys. Some groups, however, do share water holes and other essential resources.

(Bateman, 1984; Grzimek, 1972; Grzimek, 1988; Happold, 1987; Nowak, 1991; The Phoenix Zoo)

Home Range

Colobus guereza groups live in well-defined territories of about 32 to 40 acres.

Male guerezas roar loud nocturnal and dawn choruses as a means of spacing groups. Five vocal sounds have been recorded: roars, snorts, purrs, honks, and screams.

In addition to vocal communication, visual signals, such as flapping of fringe fur, facial expression, and body posture are used in aggressive communication between groups.

Tactile communication in this species includes grooming, playing, and fighting.

(Bateman, 1984; Grzimek, 1972; Grzimek, 1988; Happold, 1987; Nowak, 1991; The Phoenix Zoo)

Guereza are the second most folivorous of the Colobus species. Their diet consists primarily of leaves (especially from Celtis durandii, or Hackeberry Tree) with about 58% of young unripe leaves, 12.5% mature leaves, 13.5% fruits, 4% leaf buds, and 2% blossoms. However, this distribution is highly varied seasonally and geographically; thus at times mature leaves may account up to 34% of the diet. Guerezas seem to prefer leaves that are less susceptible to seasonal fluctuations. Guereza get water from dew and the moisture content of their diet, or rainwater held in the tree trunk hollows. In captivity C. guereza is fed monkey chow, fruits and vegetables.

Natural enemies of the guereza are crowned hawk eagles, leopards, and sometimes chimpanzees.

(Bateman, 1984; Grzimek, 1988; Kingdon, 1987; Metro Washington Park Zoo, 1995; Nowak 1991, http://www.aza.org/aza/ssp/colmonk.html)

Natural enemies of guerezas are crowned hawk eagles, leopards, and sometimes chimpanzees.

(Bateman, 1984; Grzimek, 1988; Kingdon, 1987; Metro Washington Park Zoo, 1995; Nowak 1991, http://www.aza.org/aza/ssp/colmonk.html)

As herbivores which serve as prey for several other species, these monkeys may play an important role in food webs.

These monkeys do not really initiate contact with humans. Therefore, the only negative effects from these black and white monkeys are the few instances when guerezas eat agricultural crops, probably due to inhospitable environmental conditions.

(Grzimek, 1988)

Guerezas are used in animal testing concerning human diseases, behavior, and physiology. For example, studies have been performed that test for certain behavioral responses when the territory of a guereza group is threatened. Another study tested the effects of rickets (vitamin-D deficiency) on guerezas. Other studies deal with how phenotypic variability is inversely related to selection intensity. A final example is a study dealing with the effects of an experimental serum for Mycobacterium bovis. The data collected in these studies has proved invaluable.

Colobus guereza is one of many monkey species that is sacred to the Hindu and Buddhist religions. They play a major role in these religions as icons of sacred gods.

Colobus guereza fur has been a luxury for people in some cultures and has brought in large amounts of money to trade and fur companies.

(Grzimek, 1988; Morrisey, 1995; Stetter, 1995; Suedmeyer, 1996; Von-Hippel, 1996)

There has been a drastic decline in Colubus populations over the last 100 years. Guerezas are noted in Appendix II of the Concentration in International Trade of Endangered Species (CITES). Population sizes of black and white monkeys are currently declining in many localities due to hunting and deforestation by humans. Nevertheless, since 1934 it has been reported that guerezas are "not uncommon" in suitable protected habitats. For example, guerezas are still abundant in most parts of their lowland ranges in Cameroon and the Nigerian border, and in East African reserves and parks. Although guerezas are still abundant, there is the potential for extinction of eastern populations from unrestricted skin trading.

(Honacki, 1982; Happold, 1987; Kingdon, 1987; Metro Washington Park Zoo, 1995; http://www.aza.org/aza/ssp/colmonk.html 1996)

First seen by Ruppell in 1835, black and white monkeys have been widely studied. When the range of guerezas overlaps with that of red colobus monkeys, guerezas feed from fewer species of trees (usually less than half of the usual number) and choose different plant parts. Their tolerance of a less varied diet allows them to occupy forests or thickets with impoverished or specialized flora. Their sacculated stomachs and highly efficient extraction of nutrients from their food allow them to survive on a less nutritious diet than monkeys lacking bacterial fermentation. Natural enemies of the guereza are crowned hawk eagles, leopards, and sometimes chimpanzees. If guerezas are able to live a life absent of predator threat, longevity is about 20 years (29 years in captivity).

An interesting fact about Kenyan guerezas living in high altitudes is that albinism is frequent, but for unknown reasons.

Colobus means "mutilated one". The name was given to these monkeys because they have no thumbs.

(Bateman, 1984; Grzimek, 1988; Happold, 1987; Nowak, 1991)