Cercopithecus neglectus Schlegel, 1876

Nomenclature and Size

De Brazza's monkey (Cercopithecus neglectus Schlegel, 1876) is the most sexually dimorphic guenon species: males weigh around 7 kilograms, while females weigh around 4 kilograms.

Adult Fur Coloration

Adult De Brazza's monkeys have grey agouti fur, a reddish-brown back, black limbs and tail, and a white rump.

Cheek Pouch Function

Individuals of both sexes have cheek pouches, which they use to carry food while foraging.

Sexual Dimorphism Markings

Males have a distinct blue scrotum; females have a red perianal region and visible nipples.

Juvenile Appearance

Juveniles do not have the darker adult coloration on the extremities, but they retain white stripes and a red rump.

Infant Appearance

Infants are a uniform brown agouti, and only have a small beard.

Distinguishing Species Features

A white muzzle and beard, an orange crescent on the forehead, and white stripes on the thighs set this species apart from other guenons.

Common Name Etymology

Because of this distinctive appearance, the monkey is sometimes called the "Ayatollah Monkey", named for Ruhollah Khomeini, the similarly bearded Grand Ayatollah.

Geographical Range

De Brazza's monkeys range across swamps, bamboo stands, and dry mountain forests across Angola, Cameroon, the Central African Republic, the Republic of the Congo, the Democratic Republic of the Congo, Equatorial Guinea, Ethiopia, Gabon, Kenya, South Sudan, Nigeria, and Uganda.

Unconfirmed Range Records

They may also be present in Tanzania, though these reports have not been confirmed.

Habitat Association with Water

Troops are found almost exclusively near water, and rarely travel farther than 1 km away from a river or tributary.

Swimming Behavior

Because of this habit, they can sometimes be seen swimming.

Habitat Vegetation Preference

The monkeys prefer dense forest and thick vegetation, and only enter more open forest areas to feed.

Arboreal and Terrestrial Activity

They are mainly arboreal, but descend to the ground to feed on herbaceous plants.

Population Estimate Status

Due to the species' cryptic nature, there is no accurate population estimate for the entire range of De Brazza's monkey.

Sexual Maturity Timing

Female De Brazza's monkeys reach sexual maturity around 5 years of age, while males do not reach maturity until closer to 6 years of age.

Natal Group Dispersal

Most juvenile males leave their natal group before they reach maturity.

Breeding Season

The main breeding season runs from February to March, though females can also enter estrus during periods of high food availability.

Gestation Period

Gestation lasts between 5 and 6 months.

Infant Development and Weaning

An infant stays close to its mother for the first year of life, when it is weaned.

Reproductive Output

Females usually give birth to one infant at a time. Twins are born only rarely, and there is a one-year interval between successive births.