Population decline of the black and white colobus monkey (Colobus guereza) in the Kakamega Forest, Kenya

Abstract

Groups of black and white colobus monkeys, or guerezas (Colobus guereza), in a study site in the Kakamega Forest, Kenya, have declined in number from 18 groups in 1992 to 12 groups in 1998. This decline occurred largely in the eastern half of the study site, and was not offset by an increase in group size. The western half of the study site has areas next to buildings, on the edge of the forest, where guerezas supplement their diet with soil, and it has more human foot traffic which might reduce predation levels; these factors might be partially responsible for holding the number of guereza groups in the western half steady while forest degradation takes its toll on guerezas in the eastern half. This decline in guerezas is of particular concern since it took place in an area of forest that has not decreased in size and because guerezas are among the least sensitive primates to forest degradation.