Eastern Black-and-White Colobus Monkey

Black & white colobus monkeys inhabit equatorial areas of Africa - Nigeria, Cameroon, Ethiopia, Kenya, Uganda, Tanzania, N Congo, E Gabon, Central African Republic, NE Zaire, W Kenya, NW Rwanda, and S Sudan. 

Head and body length – 18 to 27 inches; tail length – 20 to 35 inches; weight – 12 to 32 lbs.  Coat: glossy black, face and callosities surrounded by white, U-shaped mantle of varying length on sides and rear of back, outside of thigh variably whitish, tails variably bushy and whitish or yellowish from the tip towards the base.  Point of nose nearly touches the mouth.  Newborns have a natal coat that is completely white, shorter, and downier than the adult coat.  This natal coat changes to the adult coat color between 5 to 10 months.  Infant skin lacks dark pigment at birth.  Their hands and feet turn black at approximately 3 months.  At birth, newborns are approximately 8 inches long and weigh an average of 0.9 lbs.

The life span is about 20 years in the wild and about 29 years in captivity.

Black & white colobus monkeys are generally diurnal and arboreal residents of deep forest.  When trees are not densely packed, they will feed and travel on the ground.  They also inhabit dry, moist, or riparian forests that are either in lowlands or up to 10,825 feet above sea level.  They are most abundant in secondary growth forests or along rivers. 

Black & white colobus monkeys live in sexually mixed groups of 8 to 15 individuals.  One adult male and three or four reproducing females with adolescents and infants is the typical composition of such family groups.  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 their birth group for life. These females are thought to be close relatives that display their friendly intra-group relationships with mutual grooming and well-developed "infant transfer.”  This latter phenomenon is observed soon after birth when an infant is handled by several females and is carried as far as 80 feet away from its mother.  A mother may even suckle the infant of another female and her own simultaneously.  Females produce a single young after a 5-month gestation.  Intervals between offspring are about every 20 months.

Unlike females, young males leave their birth group before they reach sexual maturity.  If a male does not leave voluntarily, the dominant male will force him out of the troop.  When young males leave, they lead a solitary life or temporarily associate with other solitary males.  Some black and white colobus monkey males eventually take over their own harem and create a new birth group.  When a new male takes over a harem infanticide occurs – the new male kills as many of the offspring as he can to stimulate estrous in those females with young so he can breed.  There is no true leader of a troop, but strong males usually take leadership roles.  Black & white colobus monkeys live in well-defined territories of about 32-40 acres.

Territories of different troops may overlap marginally; males with leaps and cries, hand-to-hand communication, roars, and occasional chasing and fighting vigorously defend boundaries.  Additional displays of the white fringe fur flapping up and down serve as warnings to other monkeys.  Some groups, however, do share water holes and other essential resources.

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

The black & white colobus monkey is the second most folivorous of the Colobus species.  Diets consist primarily of leaves (especially from Celtis durandii, the Hackeberry Tree) made up of the following types: about 58% young unripe leaves, 12.5% mature leaves, 13.5% fruits, 4% leaf buds, and 2% blossoms.  This distribution is highly varied seasonally and geographically; and at times, mature leaves may account up to 34% of the diet.  This species of colobus monkey seems to prefer leaves that are less susceptible to seasonal fluctuations.  Water is obtained from the following sources: dew, the moisture content of the diet and rainwater held in tree trunk hollows.

Hind legs are long and well muscled for leaping and bounding amongst branches.  Rump calluses allow animals to sit for long periods on slender branches without discomfort.

Black & white colobus monkeys 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 two subregions.  The upper region contains a neutral medium, which is necessary for the fermentation of foliage by anaerobic bacteria.  The black and white colobus monkey's large salivary glands provide a buffer fluid between the two regions of the stomach.  The large stomach capacity accommodates large volumes of relatively unnutritious food.  The slow passage of material through the stomach is essential for fermentation.  In fact, the stomach contents may be equal to or more than 25% of the adult’s body weight.  This adaptation allows this species to digest leaves more efficiently than any other primate.

The bacterium in the upper region of the stomach breaks down cellulose and releases energy.  It can also deactivate many toxins, allowing this species to eat plant items containing toxins.  Plant defense compounds are found in all trees, but are found in higher concentrations in trees growing in nutrient poor soils.  It is costly for trees in these areas to replace leaves eaten by plant-eaters.

To obtain important minerals like calcium, potassium, sodium, magnesium, and copper, black & white colobus monkeys eat soil.

Black & white colobus monkeys are used in biomedical research, behavior studies, and physiological studies.  For example, studies have been performed that test behavioral responses when the territory of one group is threatened.  Another study tested the effects of rickets (vitamin-D deficiency) on the bodies of black & white colobus monkeys.

The black & white colobus monkey is one of many monkey species that is sacred in 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.

Natural enemies of the black & white colobus monkeys are crowned hawk eagles, leopards, and chimpanzees.

An interesting fact about Kenyan black & white colobus monkeys living in high altitudes is that albinism is frequent, but for unknown reasons.

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

In this genus, there are 4 species and 16 to 22 subspecies.  In Colobus guereza, there are 10 subspecies.  Subspecies are differentiated by the varying degrees in the amount and placement of the white markings found in the adult coat.

The Masai and other East African tribal peoples have used the coat of the black & white colobus monkey as a “majestic” adornment since ancient times.

There has been a drastic decline in colobus populations over the last 100 years.  Colobus guereza are Appendix II in International Trade of Endangered Species (CITES), and IUCN gives them a low conservation rating.  Population sizes of black and white colobus monkeys are currently declining in many localities due to hunting and deforestation by humans.  Nevertheless, since 1934 it has been reported that black & white colobus monkeys are "not uncommon" in suitably protected habitats.  For example, they are still abundant in most parts of their lowland ranges in Cameroon along the Nigerian border, and in East African reserves and parks.  Although still abundant, there is the potential for extinction of eastern populations from the unrestricted fur and bushmeat trades.

In September 1977, three eastern black-and-white colobus monkeys arrived here for the first time.  Unfortunately, all three died that same month.  This species did not occur in the collection again until May 1996.  They have successfully bred here.