De Brazza’s monkey is a large primate, native to Africa. This monkey belongs to guenons, otherwise known as the genus Cercopithecus. De Brazza’s monkey is so called after a Franco-Italian explorer Pierre Savorgnan de Brazza, who established Brazzaville, the capital city of Congo - one of the countries they are endemic to. Although these primates are generally arboreal, they can also spend their time in water and on the ground.
De Brazza’s monkeys are found over a large area, stretching from Cameroon southwards to northern Gabon, Congo and northern Angola as well as eastwards, covering much of the Democratic Republic of Congo and reaching southern Central African Republic and eastern Uganda. Additionally, isolated populations of these monkeys occur in western Ethiopia, far south of Sudan and eastern Kenya. Preferred habitat of this species is forested area nearby a river or waterway. Hence, De Brazza’s monkeys generally inhabit dense swamp forests, lowland tropical forests and mountain forest.
These primates are both terrestrial and arboreal. De Brazza's monkeys are social animals, forming very small groups of 4 - 10 individuals, although larger units of up to 35 animals have been recorded. They are highly territorial creatures and don't tend to associate with other monkeys, although captive individuals do associate with other species. When threatened, they usually climb onto trees and remain motionless. They forage in the early morning and evening, collecting food by hand. When moving around, De Brazza's monkeys use all of their four legs, unlike some monkeys. They are also good swimmers. Juveniles try to imitate their fathers, practicing dominance. The greater part of their active time is spent roaming with arched tails and slamming branches. Meanwhile, the dominant male may sometimes be challenged by another male of the area.
As omnivorous animals, De Brazza's monkeys feed upon a wide variety of food, including leaves, flowers and mushrooms, supplementing this diet with occasional beetles, termites, and worms. However, their main food is fruits.
The reproductive system of this species varies, depending on location. Thus, populations in some areas exhibit polygynous mating system, where a dominant male lives and breeds with 9 - 10 females. In other areas, De Brazza's monkeys are monogamous: a male and a female form a long-lasting pair, living in a family group with their young. They generally breed during periods of abundant food, although the population in the equatorial rainforest is known to breed in February-March. Gestation period lasts for 5 - 6 months, yielding one baby. As soon as born, the baby clings to the belly of its mother, where it finds protection from potential predators. The juvenile begins eating solid food at 2 months old and is weaned at about 1 year old. Young of both sexes are mature at 5 - 6 years old, after which males usually disperse, while females continue living with their mothers.
De Brazza’s monkeys are presently threatened by loss of their natural habitat as a result of continuous forest clearance for agriculture and timber. These primates are hunted for their meat. The latter concern is compounded by expansion of the bushmeat trade.
This species is widespread but not very abundant over its range. It is suggested that the total population size of the De Brazza’s monkeys is over 100,000 individuals. According to the IUCN Red List, an isolated population, recently discovered in Mathews Range Forest Reserve, was estimated to 200-300 individuals. Overall, De Brazza’s monkeys are currently classified as Least Concern (LC) on the IUCN Red List.
Due to their frugivorous diet, De Brazza’s monkeys are likely to act as seed dispersers of their range. Additionally, they are prey items for some local predators.