Drill (mammal)
Taxonomy and Evolution
The drill (Mandrillus leucophaeus) is a primate of the family Cercopithecidae, closely related to baboons and even more closely to mandrills. The genus Mandrillus, was once thought to be a subgenus of the baboon genus Papio, but recent research has determined that they should be separated into their own genus.
The drill is a short-tailed monkey up to 70 cm (28 in) in length, similar in size to a baboon. Sexual dimorphism is pronounced in the species, with males typically being about twice the size of females. Males can weigh 30–50 kg (66–110 lb), females weigh 11–14 kg (24–31 lb). The body is overall a dark grey-brown. Mature males have a pinkish face with a high crest of hair on the head.
Distribution and Habitat
The drill is found only in Cross River, Nigeria, southern Cameroon (south to the Sanaga River), and on Bioko Island, part of Equatorial Guinea. Its distribution is limited by the extent of rainforest, its preferred habitat, and the distribution of its major food resources. It is primarily a terrestrial species, but it climbs trees to feed and to sleep.
Behaviour and Ecology
Drills live in large social groups, ranging from 20 to 30 individuals, up to hundreds of individuals. These groups are made up of one dominant male, multiple females, and their offspring. The dominant male defends the group and is the only one who mates with the females.
Drills are omnivorous, eating a wide variety of foods. They primarily eat fruit, but also consume roots, leaves, and small animals such as insects and rodents. They are also known to eat soil and clay for its mineral content.
Conservation Status
The drill is one of Africa's most endangered primates, and is listed by the IUCN as the highest conservation priority of all African primates. Drills are threatened by habitat loss and by hunting for bushmeat. The species is part of international conservation and breeding programs.