A guenon monkey with several colour variations over its range. Females stay with their mothers, forming territorial female-dominated groups with only a single male.

Subspecies
Some variations across its range are sometimes given subspecies rank, with the blue monkey itself being C.m. stuhlmanni, the silver monkey being C.m. doggetti and the Golden monkey being C.m. kandti. These two have differently coloured mantles, and are found in W Uganda, Rwanda and Eastern Congo.

Statistics
49-66cm not including the tail, with females weighing 4.3kg and males 7.9kg.

Physical description
A long tailed monkey with a grizzled brown, short coat, a bluish grey mantle over the shoulders, a black belly and limbs and a dark face with a pale yellowish 'diadem' on its forehead.

Distribution
North Western Angola to South Western Ethiopia and down through southern Africa.

Habitat
Rainforest and montane bamboo forest.

Diet
Fruit, flowers, nectar, leaves, shoot, insects, birds and small mammals (including bush babies).

Behaviour
Blue monkeys live in groups of about 20-40, often with only one adult male. The females are often related. The females will defend their territory against neighbouring groups, with males only staying with the group between a few weeks and a couple of years at most. Adult males make loud calls that are specific to the individual.

Reproduction
Breeding is seasonal, depending on the area. A single youngster is born after a gestation period of 5 months, fully furred and with its eyes open. The mother gives birth wherever she happens to be, and birth is usually at night. She eats the placenta and licks the baby clean as it clings to her belly. Other females in the group show great interest and try to hold new infants. Nursing becomes less frequent after the first few months, but continues until the next birth, usually after 2 years. Male offspring leave the group when they reach sexual maturity.

Conservation status
Not currently threatened.