The olive baboon (Papio anubis), also called the Anubis baboon, is a member of the family Cercopithecidae Old World monkeys. The species is the most wide-ranging of all baboons, being native to 25 countries throughout Africa, extending from Mali eastward to Ethiopia and Tanzania. Isolated populations are also present in some mountainous regions of the Sahara. At closer range, its coat is multicoloured, due to rings of yellow-brown and black on the hairs. The hair on the baboon's face is coarser and ranges from dark grey to black. The olive baboon is one of the largest species of monkey; along with chacma baboons, mandrills, and muriquis. The head-and-body length can range from , with a species average of around . At the shoulder on all fours, females average against males, which average . The typical weight range for both sexes is reportedly , with males averaging and females averaging . Some males may weigh as much as .
Like other baboons, the olive baboon has an elongated, dog-like muzzle. The tail almost looks as if it is broken, as it is erect for the first quarter, after which it drops down sharply.
Distribution and habitat
The species inhabits a strip of 25 equatorial African countries, very nearly ranging from the east to west coasts of the continent. The grasslands, especially those near open woodland, do make up a large part of its habitat, but the baboon also inhabits rainforests and deserts. Female social rank is determined largely by heredity, with daughters inheriting their rank in line with their mother's, and adult females forming the core of the social system.
Occasionally, groups may split up when they become so large that competition for resources is problematic, but even then, members of matrilines tend to stick together.
thumb|left|Troop in Kenya
A female often forms a long-lasting social relationship with a male in her troop, known as a "friendship".
Males establish their dominance more forcefully than females.
Despite being hierarchical, baboons appear to be "democratic" when it comes to deciding the direction of collective movement. Individuals are more likely to follow when multiple decision-makers agree on what direction to go rather than simply following dominant individuals.
Reproduction and parenting
thumb|Female with suckling young
thumb|Female with baby in [[Queen Elizabeth National Park, Uganda]]
thumb|Olive baboon carrying a juvenile on her back at [[Mole National Park in Ghana]]
Females are sexually mature at seven to eight years old, and males at seven to 10 years. The swelling makes it difficult to move and increases the female's chance of microbial or parasitic infection. Males guard their partner against any other male trying to mate with her. Unless a female is in a multiday consortship, she often copulates with more than one male each day. Multiple copulations are not necessary for reproduction, but may function to make the actual paternity of the female's offspring ambiguous. This lack of paternal certainty could help reduce the occurrence of infanticide.
thumb|left|Adult [[social grooming|grooming young in the Ngorongoro Conservation Area]]
Newborns have black natal coats and bright pink skin. Females are the primary caregivers of infants, but males also play a role. In general, higher-ranking females are usually more relaxed parents than females of lower rank, which usually keep their offspring close to them.
Communication
thumb|Face of an olive baboon
Olive baboons communicate with various vocalizations and facial expressions. Throughout the day, baboons of all ages emit the "basic grunt". Adults give a range of calls. The "roargrunt" is made by adult males displaying to each other. The "cough-bark", and the "cough geck" are made when low-flying birds or humans they do not know are sighted. A "wa-hoo" call is made in response to predators or neighbouring groups at night and during stressful situations. Most animals only look for food at one level; an arboreal species such as a lemur does not look for food on the ground. The olive baboon searches as wide an area as it can, and it eats virtually everything it finds. The olive baboon eats leaves, grass, roots, bark, flowers, fruit, lichens, tubers, seeds, mushrooms, corms, and rhizomes. In a field study, such behaviour was observed as starting with the males of one troop and spreading through all ages and sexes.
Conservation status
The olive baboon is listed as least concern on the IUCN Red List because it is widespread with a large global population and not threatened by a range-wide population decline.