a male Mandrill
|Range||Nigeria, southern Cameroon, Gabon, Equatorial Guinea, and Congo.|
The Mandrill (Mandrillus sphinx), is a species of Old World monkey, Its closely related to the baboons and even more closely to the drill. It is found in southern Cameroon, Gabon, Equatorial Guinea, and Congo. Mandrills mostly live in tropical rainforests and forest-savanna mosaics. They live in groups called hordes. Mandrills have an omnivorous diet consisting mostly of fruits and insects. Their mating season takes place from June to October.
Both the mandrill and the drill were once classified as baboons in genus Papio, but recent research has determined they should be separated into their own genus, Mandrillus. Mandrills are the world's largest monkeys. Charles Darwin wrote in The Descent of Man that "no other member in the whole class of mammals is coloured in so extraordinary a manner as the adult male mandrills." The mandrill is listed as Vulnerable by IUCN.
The mandrill is the most colorful primate. It has an olive green or dark grey pelage with yellow and black bands and a white belly. Its hairless face has an elongated muzzle with distinctive characteristics such as a red stripe down the middle and protruding blue ridges on the sides. It also has red nostrils and lips, a yellow beard and white tuffs. The areas around the genitals and the anus are multi-colored, being colored red, pink, blue, scarlet, and purple. They also have pale pink ischial callosities. The coloration of the animal is more pronounced in dominant adult males. Both sexes have chest glands which are used in olfactory communication. These, too, are more prominent in dominant adult males. Males also have longer canines than females, with an average of 4.5 cm (1.8 in) and 1.0 cm, respectively.
The mandrill has one of the greatest sexual dimorphisms among the primates. Males typically weigh 19–37 kg (42–82 lb), with an average mass of 32.3 kg (71 lb). Females weigh roughly half as much as the male, at 10–15 kg (22–33 lb) and an average of 12.4 kg (27 lb). Exceptionally large males can weigh up to 54 kg (119 lb). The average male is 75–95 cm (30–37 in) long and the female is 55–66 cm (22–26 in), with the short tail adding another 5–10 cm (2–4 in). The shoulder height while on all fours can range from 45–50 cm (18–20 in) in females and 55–65 cm (22–26 in) in males. The male Mandrill is the heaviest monkey in the world, although its total length is relatively short due to its vestigial tail and, due to its high sexual dimorphism, baboons such as the Chacma and Olive average around the same weight. Compared to the largest baboons, the mandrill is more ape-like in structure, with a muscular and compact build, shorter, thicker limbs that are longer in the front and almost no tail. Mandrills can survive up to 31 years in captivity. Females reach sexual maturity at about 3.5 years.
Ecology and Activities
The mandrill is found in Nigeria, southern Cameroon, Gabon, Equatorial Guinea, and Congo. Its distribution is bounded by the Sanaga River to the north and the Ogooué and White Rivers to the east. Recent research suggests mandrill populations north and south of the Ogooué river are so genetically different as to be separate subspecies. Mandrills prefer to live in tropical rainforests and forest-savanna mosaics. They also live in gallery forests adjacent to savannas, as well as rocky forests, riparian forests, cultivated areas and flooded forests and stream beds. Mandrills will cross grass areas within their forest habitats.
The mandrill is an omnivore. It usually consumes plants, of which it eats over a hundred species. It prefers to eat fruits, but will also eat leaves, lianas, bark, stems, and fibers. It also consumes mushrooms and soil. Carnivorously, mandrills mostly eat invertebrates, particularly ants, beetles, termites, crickets, spiders, snails, and scorpions. It will also eat eggs, and even vertebrates such as birds, tortoises, frogs, porcupines, rats, and shrews. Mandrills likely will eat larger vertebrates when they have the opportunity, such as juvenile bay duikers and other small antelope. Large prey are likely killed with a bite to the nape with the mandrill's long canines. In males, the canines can measure over 6 cm (2.4 in) in length. 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 foods (4.1%), with other foods making up the remaining (1.4%).
Mandrills are preyed upon mainly by leopards, in addition to crowned eagles and african rock pythons. They may be bitten and killed by gaboon vipers when they accidentally rouse the venomous snake. It is thought that most predators are a threat mainly to young mandrills, with the likelihood of predation decreasing in adult females and especially adult males. In a study where a mandrill troop was exposed to stimuli relating to their natural predators, only the leopard caused the larger part of the group to flee into trees. However, the large, dominant males were observed to remain in response to the images of the natural predators, even the leopard, and pace back and forth whilst baring their teeth, generally indicating aggression and the defensive role they may play in such circumstances.
Mandrills are mostly terrestrial but they are more arboreal than baboons and feed as high as the canopy. When on the ground, mandrills walk by digitigrade quadrupedalism (walking on the toes of all four limbs). When in the trees, they often move by lateral jumps. Mandrills are mostly diurnal, with activities extending from morning to evening. They sleep in trees at a different site each night. Mandrills have been observed using tools; In the wild and in captivity, mandrills have been observed using sticks to clean themselves.
Social Behavior and Reproduction
Status and Conservation
The mandrill is considered vulnerable and is affected by deforestation. However, hunting for bushmeat is the more direct threat. Mandrills are particularly threatened in the Republic of the Congo. Nevertheless, there have been captive-bred individuals that have been successfully reintroduced into the wild.