Campbell's Monkey looks similar to its Guenon relative De
Brazza's Monkey, although its orange brow, black hairline
and whitish muzzle are more muted. It lives mainly in undisturbed forests of West Africa, particularly in the Ivory Coast. It is related to the Mona Monkeys, particularly to the similar-looking Lowe's Mona
(Lowe's Guenon) which used to be thought a subspecies.
Campbell's Monkey has the second most complex verbal language known of land mammals, after humans, combining just six sounds to make 20 different messages.
Their communication includes specific warnings that can differentiate the danger from a falling branch to an avian predator (eagle) to a leopard, and the degree of that danger as it evolves.