Olive colobus | |
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Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Primates |
Family: | Cercopithecidae |
Genus: | Procolobus |
Species: | P. verus |
Binomial name | |
Procolobus verus (van Beneden, 1838) |
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Olive Colobus range |
The olive colobus monkey (Procolobus verus), also known as the green colobus or Van Beneden's colobus, is a species of primate in the family Cercopithecidae. Its English name refers to its dull olive upperparts. It is the smallest example of all colobine monkeys and is rarely observed in its natural habitat because of its cryptic coloration and secretive nature. It is found in the rain forests of West Africa, ranging from southern Sierra Leone to Nigeria. The olive colobus is classified as near threatened by the IUCN Red List, the cause of its decline attributed to habitat loss and hunting. Though much of the land within the range of the olive colobus has been affected by human activities, it retains its ability to thrive in small degraded forest fragments.
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. These monkeys have a unique feature in that their thumb is severely reduced on their forefeet, while the hind feet retain five digits. The feet of the olive colobus are also abnormally large compared to other African colobine species.
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 fact that olive colobus monkeys utilize this type of fermentation also relates to their lack of fruit consumption because things such as fruits that contain high levels of acid can lower the pH of the stomach causing negative and sometimes lethal effects on microorganisms living within the stomach.