Distribution:  Most extensively distributed of all baboons, from Sahel in northwest Africa across central Africa to Sudan, Kenya and Tanzania.  In East Africa, distribution is bounded by changes in vegetation. 

Habitat:  Olive baboon’s adaptation to terrestrial life in grassland habitats has made it most widespread African primate.  Found throughout savannah, woodland and arid zones wherever trees or cliffs occur.  Availability of water and secure sleeping places are of primary importance in habitat.

Food and Feeding Methods:  An omnivorous opportunist, olive baboon changes diet according to region, season and even time of day, and incorporates virtually any edible plant in its range.  Grass is principal food in open savannah, with bark, stems, leaves, flowers, fruits, seedpods, roots and resin or gum taken in different seasons.  Invertebrates provide important dietary supplement, especially in arid areas.  Vertebrates, including reptiles, amphibians, small birds and rodents, and young of antelope, are not deliberately sought but taken when opportunity arises. Usually only adult males take hares and young antelope but some troops are known for cooperative hunting.  Feed from hand to mouth while sitting but no evidence of tool use.  Troop keeps together while foraging.

Social Behavior:  Diurnal, multi-male troops composed of resident females and young in kinship groups associated with specific males, non-territorial, terrestrial.  Baboons live in troops of 8 to over 200 but typically number 30 to 40.  Adult females outnumber males about 3 to 1 and immature classes make up at least half of total.  Females make up stable core and never leave their natal troop, whereas males emigrate during adolescence and transfer repeatedly between troops.  A strict rank hierarchy exists between adult females and offspring: each female heads a kinship group in which her young are ranked according to age in descending order, beginning with youngest.  In relations between kinship groups, young take rank of the matriarch of their group so that a low-ranking adult female has to defer to an infant of a superior female.  By 2 ½ years, a female’s rank is fixed for life.

Male offspring remain in kinship group and subordinate to their mothers until about 4 years when they become adolescent and dominant over all females.  Male reproductive success is linked to dominance status, so low-ranking males gain the most by emigrating to new troops, but it is also affected largely by nonsexual relationships with females.   Females prefer to mate with dominate males but also with males they regularly associate with or are ‘pair-bonded’ with.  Each female has 1 or 2 favorite males with whom she spends more time with than other baboons.  Males who associate with females play a ‘godfather’ role to their offspring for first 2 years of life.  When females or juveniles are bullied by other troop members, godfathers come to their aid.  Low-ranking females receive protection from male protectors when high-ranking females try to steal their infants.  Godfathers have been known to even act as foster parents to juveniles whose mothers have died.  Males benefit from godfather role by increasing changes of breeding, as a means of emigrating successfully into a new troop and by using infants, juveniles and adult females as buffers in encounters with more dominant males.

Adult males form coalitions or ‘cabals’ that represent cooperation in certain situations and have elements of hierarchy in them.  By forming associations, males gain an advantage over dominant males and increase reproductive success, but also act together to protect the troop against predators.  Presence of adult males that are twice as big as females deters attacks from large predators and allows baboons to venture into open grassland where they are more vulnerable.  When foraging troop is alerted to danger by alarm bark, adult males move in direction of disturbance and display vigilance behavior.  As troop escapes amid loud barking, males and occasionally females form rearguard and sometimes go on offensive.  When disturbed in trees at night, known to defecate on predators below.  Leopard is most effective baboon predator.

Home ranges vary from 1,000 to 10,000 acres, depending on habitat and troop size.  Ranges usually overlap but different troops avoid each other unless resources are scarce, leading to intertroop aggression.

Baboon society is highly complex and variable, with a communication system capable of signaling a wide range of emotions.  Posture, movements, facial expressions and vocalizations are all used to register changes in emotional state.  Any disturbance, internal or external, is apt to provoke disciplinary action by dominant males.  Vocalizations include barks, grunts, shrieks and screeches among many others.  The greatest part of social interactions is invested in social grooming.  Web of relationships, affiliations and rank order within troop can be explained by who is grooming whom and how.  Direction of grooming, other than mothers with infants, is usually from lower to higher rank. 

Reproduction:  Female baboons spend about half their adult lives taking care of offspring and another third pregnant.  Females first conceive at about 6 years and produce young at roughly 1 ½ to 2 year intervals.  Female reproductive condition is plain to see from color and degree of swelling of sexual skin on rump, which turns bright pink during estrous.  Female sexual swelling is largest of all monkeys.

There is no strict birth season but conception tends to peak during rainy season when food is more abundant. 
After gestation of 6 months, 1 young is born most often at night.  Bright pink skin and black hair begin to change at 3 months and is same as adult coloring by 6 months.  Completely dependent young clings to mother for first month or so, begins climbing on own at 2 months, and begins riding mother in jockey position at 6 to 12 weeks.  At 3 to 4 months, young begin associating with other infants in maternity subgroups formed by mothers and begin to feed on own.  Yearling baboons are quite independent and can feed on own, though they continue to depend on protection and guidance of mothers for another year.  Males don’t get opportunity to breed until at least 8 to 10 years.

Status:  Remains widespread and common in spite of vigorous trapping, shooting and poisoning.  Listed as vermin by African Convention.  Wherever range encounters that of other baboon species, there are hybrid zones, indicating olive baboon is still actively expanding and causing neighboring, smaller baboons to contract.

Adaptations:  In competition for food, groups with more females prevail, an incentive for large troops in all baboon species.

Extreme projection of muzzle allows baboons to make visually emphatic signals, such as ritualized yawns.

Sexual dimorphism results in much bigger males who act as protectors of group.

 Head/Body Length:    1 ½ - 3 ¾ ft.                              Tail Length:    1 ½ - 2 ¼ ft.   
Shoulder Height:                  2 ¼ ft.  (male)       1 ¾ ft.   (female) 
Weight:                            48 - 110 lbs. (male)   24 - 66 lbs. (female)