Olive Colobus

Procolobus verus is a small-bodied mammal with an average body weight of 4.6 kilograms for males and 4.1 kilograms for females. The olive colobus are greenish-brown in color with the hairs transitioning from greenish-yellow at the root, and becoming darker towards the tip. The under side of the olive colobus is lighter in color and the hairs found on the face are stiff and dark. Their coloration allows them to stay camouflaged within the trees reducing the risk of predation. Like all colobine monkeys, olive colobuses have a unique feature in that in their hands, their thumbs are severely reduced, while their feet retain fully functional big toes. The feet of the olive colobus are also abnormally large compared to other African colobine species.

Diet. The natural habitat of the olive colobus includes second growth within tall forests, palm forests and swamps, where they feed in the lower and middle vegetation strata. The olive colobus is mainly folivorous, although it may consume fruits and seeds when available. The diet consists primarily of young leaves, and they tend to avoid mature leaf parts altogether. This is related to the fact that it is a forestomach fermenter with a small body size, which requires it to obtain a very high quality diet. …

The olive colobus monkey is a very cryptic and shy animal, which can make the observation and understanding of its behavior difficult. What is known about interactions between olive colobus monkeys and other related species shows that their social structure is very complex. Olive colobus monkeys are found in small groups containing multiple breeding males, several females, and their infants. Though found in groups of only a few individuals, olive colobus monkeys are almost always seen in association with other monkeys, particularly the Diana monkey, Cercopithecus diana. There have been many suggestions as to how this relationship benefits the olive colobus, such as reducing the risk of predation. A piece of evidence that gives support to this idea is the willingness of the olive colobus to travel to higher altitudes in the tree tops to feed when other species are nearby. In addition to serving as a means of predator avoidance, the close association with Diana monkeys is a mechanism used by male olive colobus monkeys to obtain new female mates. The olive colobus mating system is unique in that unlike many species living in small groups, there is no evidence of male monopolization over females. …