The species is sexually dimorphic, as males have a larger body, longer canine teeth and brighter coloring.

Their preferred foods are fruit and seeds, but mandrills will consume leaves, piths, mushrooms, and animals from insects to juvenile bay duiker.

[9] Historically, some scientists placed the mandrill and the closely related drill (M. leucophaeus) in the baboon genus Papio.

Morphological and genetic studies in the late 20th and early 21st centuries found a closer relationship to white-eyelid mangabeys of the genus Cercocebus.

[16] Cytochrome-b sequences suggest that mandrill populations north and south of the Ogooué River split 800,000 years ago and belong to distinct haplogroups.

[24] The coat of the mandrill is primarily grizzled or banded olive-brown with a yellow-orange beard and sparse, light hairs on its underside.

Females have more subdued facial coloring, but this can vary between individuals with some having stronger red and blue hues and others being darker or almost black.

Charles Darwin wrote in The Descent of Man: "no other member of the whole class of mammals is coloured in so extraordinary a manner as the adult male mandrill".

[32] The blue ridges on males contrast with both the red facial hues and the green foliage of their environment, helping them stand out to other individuals.

[34] The mandrill lives in west-central Africa, including southern Cameroon, mainland Equatorial Guinea (Río Muni), Gabon and parts of the Republic of the Congo.

[38] One study found the mandrill's diet was composed of fruit (50.7%), seeds (26.0%), leaves (8.2%), pith (6.8%), flowers (2.7%), and animal matter (4.1%), with other foods making up the remaining 1.4%.

[38] In particular, mandrills consume leaves from the arrowroots Haumania liebrechtsiana and Trachyphrynium braunianum, as well as the piths of ginger plants like Renealmia macrocolia and species in the genus Aframomum.

[38] The rest of a mandrill's diet is largely made up of invertebrates, particularly ants, termites, crickets, spiders, snails, and scorpions.

[45] Wild mandrills have tested positive for SIV, enteroviruses of the species EV-J and astroviruses, including a human variant.

Strong connections with their relatives may lead to support during conflicts, higher survival rate of offspring and a longer lifespan for females.

As a result, the coloration of the male mandrill may be intended to attract attention in a social structure with no long-term relationships between mates.

[58] During grooming, subordinates prefer to pick at other mandrills from behind, in order to minimize eye contact and give them more time to flee if the more dominant individual attacks.

Upon gaining alpha status, males develop larger testicles, redder faces and posteriors, more secretion from the chest glands and fatter sides and rumps.

[69] Mandrill gestation lasts an average of 175 days with most births taking place between January and March, during the wet season.

Over the next two or three months, they develop their adult hair color on the body, limbs and head while the flesh-colored face and snout darken.

Threat displays involve open mouth staring, usually in combination with head bobbing, ground slapping and raised hair.

These gestures are usually performed by dominant individuals towards subordinates, who respond with bared teeth grimaces, signaling fear and aggression.

[74] Mandrills can develop and pass on new gestures; captive individuals at the Colchester Zoo, England facepalm to discourage being disturbed, particularly while resting.

During group movements, adult males produce two-phase grunts and one-syllable roars, both of which are equivalent to the "wahoo" bark of baboons.

Other group members produce "crowings", which last almost two seconds and start as a vibration and transition into a longer harmonic sound.

Short distance vocals include the "yak", a sharp, repeating, pulse-like call produced by all individuals except for adult males and made in tense situations.

[1] The mandrill appears to have suffered massive habitat loss in Equatorial Guinea and southern Cameroon, while its range in the Republic of the Congo is limited and its status is unknown.

[1] Gabon is seen as the most important remaining refuge for the species, and the country's low population density and vast rainforests make it a good candidate for mandrill conservation.

[80] The mandrill is listed under Appendix I by CITES, banning commercial trade in wild-caught specimens, and under Class B by the African Convention, which provides them protection but allows special authorization for their killing, capturing or collecting.

[1] In Gabon, most of the rainforests have been leased to timber companies but around 10 percent is part of a national parks system, 13 of which were established in 2002.