Colobus monkeys live in a wide variety of habitats throughout Africa, ranging east to west from Somalia to Guinea, and north to south from Sudan to Zambia. The colobus monkey is an arboreal species, thus it lives in forest areas of all types. The red colobus monkey, black colobus monkey and olive colobus monkey tend toward more lush rainforests, whereas the varieties of black- and-white colobus monkeys are found more often in gallery, secondary, savannah and swamp forests. Their diet generally consists of immature leaves, fruits, shoots, flowers and seeds. Colobus monkeys can thrive in many different environments due to their digestive system which features a sacculated stomach. This stomach aids in the digestion of thick cellulose walls and allows the colobus monkeys to eat plants chemically defended by things such as cyanide and strychnine. This stomach also causes them to prefer immature leaves over mature leaves.

These digestive capabilities permit a flexibility in their diet depending on environmental variables. Black-and-white colobus monkeys, for example are able to thrive in dry climates in which difficult-to-digest seeds comprise a large part of their diet (Dasilva, 1992). Black colobus monkeys in Gabon eat approximately 1.5 times as many fruits and seeds and half as many leaves and flowers when foraging with other monkey species than when foraging alone (Gautier-Hion et al., 1997). This diet flexibility allows for them to reap the benefits of protection from predation by being in close proximity to other monkeys.