Olive baboon
Template:Short description Template:Good article Template:EngvarB Template:Speciesbox
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,<ref name="Shefferly">Template:Cite web</ref> being native to 25 countries throughout Africa, extending from Mali eastward to Ethiopia<ref name= "Aerts2019">Template:Cite book</ref> and Tanzania. Isolated populations are also present in some mountainous regions of the Sahara.<ref name="Shefferly" /> It inhabits savannahs, steppes, and forests.<ref name="Shefferly" /> The common name is derived from its coat colour, which is a shade of green-grey at a distance. A variety of communications, vocal and non-vocal, facilitate a complex social structure.
Characteristics
The olive baboon is named for its coat, which, at a distance, is a shade of green-grey.<ref name="Lang">Template:Cite web</ref> At closer range, its coat is multicoloured, due to rings of yellow-brown and black on the hairs.<ref name="Rowe1996">Template:Cite book</ref> The hair on the baboon's face is coarser and ranges from dark grey to black.<ref name=Lang/> This coloration is shared by both sexes, although males have a mane of longer hair that tapers down to ordinary length along the back.<ref name=Shefferly/>
Besides the mane, the male olive baboon differs from the female in terms of weight, body and canine tooth size; males are, on average, Template:Cvt tall while standing and females measure Template:Cvt in height.<ref name=Fleagle>Template:Cite book</ref> The olive baboon is one of the largest species of monkey; along with chacma baboons, mandrills, and muriquis.<ref>Template:Cite journal</ref> The head-and-body length can range from Template:Cvt, with a species average of around Template:Cvt. At the shoulder on all fours, females average Template:Cvt against males, which average Template:Cvt. The typical weight range for both sexes is reportedly Template:Cvt, with males averaging Template:Cvt and females averaging Template:Cvt. Some males may weigh as much as Template:Cvt.<ref name=Burnie>Burnie D and Wilson DE (Eds.), Animal: The Definitive Visual Guide to the World's Wildlife. DK Adult (2005), Template:ISBN</ref><ref name=Kingdon>Template:Cite book</ref>
Like other baboons, the olive baboon has an elongated, dog-like muzzle.<ref name=Shefferly/> Its Template:Cvt long tail and four-legged gait can make it seem canine.<ref name=Nagel1973>Template:Cite journal</ref> The tail almost looks as if it is broken, as it is erect for the first quarter, after which it drops down sharply.<ref name=Lang/> The bare patch of a baboon's rump is smaller in the olive baboon than in the Hamadryas baboon or Guinea baboon.<ref name=Shefferly/> The olive baboon, like most cercopithecines, has a cheek pouch with which to store food.<ref name=Groves2001>Template:Cite book</ref>
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.<ref name="Groves2001" /> The exact boundaries of this strip are not clearly defined, as the species' territory overlaps with that of other baboon species.<ref name="Lang" /> In many places, this has resulted in cross-breeding between species.<ref name="Lang" /> For example, considerable hybridisation has occurred between the olive baboon and the hamadryas baboon in Ethiopia.<ref name="Nagel1973" /> Cross-breeding with the yellow baboon and the Guinea baboon has also been observed.<ref name="Lang" /> Although this has been noted, the hybrids have not as yet been well studied.<ref name="Lang" />
Throughout its wide range, the olive baboon can be found in a number of different habitats.<ref name="Shefferly" /> It is usually classified as savannah-dwelling, living in the wide plains of the grasslands.<ref>Template:Cite journal</ref> The grasslands, especially those near open woodland, do make up a large part of its habitat, but the baboon also inhabits rainforests and deserts.<ref name="Shefferly" /> Uganda and the Democratic Republic of the Congo, for instance, both support olive baboon populations in dense tropical forests.<ref name="Lang" />
Behaviour and ecology
Social structure
The olive baboon lives in groups of 15 to 150, made up of a few males, many females, and their young.<ref name="Lang2">Template:Cite web</ref> Female social rank is determined largely by heredity, with daughters inheriting their rank in line with their mother's,<ref name="Lang2" /><ref name="Smuts1985">Template:Cite book</ref> and adult females forming the core of the social system.<ref name="Smuts1985" /> Female relatives form their own subgroups in the troop.<ref name="Lang2" /> Related females are largely friendly to each other. They tend to stay close together and groom one another, and team up in aggressive encounters within the troop.<ref name="Smuts1985" /> Female kin form these strong bonds because they do not emigrate from their natal groups.<ref name="Strier">Template:Cite book</ref>
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.<ref name="Strier" /> Dominant females procure more food, matings, and supporters. Among olive baboons in Tanzania, high-ranking females give birth at shorter intervals to infants with a higher survival rate, and their daughters tend to mature faster than low-ranking females.<ref name="Strier" /> These high-ranking females also appear to have a higher probability of miscarriages and some high-ranking matrilines have inexplicably low fertility.<ref name="Strier" /> One theory suggests this occurs due to stress on the high-ranking females, although this theory is controversial.<ref name="Strier" /> A recent study shows top-ranking females are at risk from male harassment. Males who have recently immigrated harass females in order to induce miscarriages in females they had not yet mated with, in order to impregnate them with an offspring that is his own faster. As females with living infants often have male allies protecting their infants, it makes more sense for a male to ignore infants and channel his aggression to the group's resident pregnant females who do not currently have infants instead.<ref>Template:Cite web</ref>
A female often forms a long-lasting social relationship with a male in her troop, known as a "friendship".<ref name="Smuts1985" /> These nonsexual affiliative friendships benefit both the male and female.<ref name="Strier" /> Males benefit from these relationships because they are usually formed soon after he immigrates into a new group,<ref name="Strier" /> and helps the male integrate into the group more easily.<ref name="Strier" /> He could also potentially end up mating with his female friend in the future.<ref name="Strier" /> Females gain protection from threats to themselves and their infants (if they have any).<ref name="Strier" /> Males occasionally "baby-sit" for their female friends, so she can feed and forage freely without the burden of having to carry or watch the infant.<ref name="Strier" /> Sexually receptive females and newly immigrated males can form such friendships.<ref name="Lang2" /> These relationships are sometimes enduring and the pair grooms and remains close to each other.<ref name="Lang2" /> They also travel, forage, sleep, and raise infants together, as well as fight together against aggressive conspecifics.<ref name="Smuts1985" />
Females with high social ranks even forge friendships with multiple males at once. Another advantage of these friendships is it enables females to gain protection from the unwanted advances of males aiming to mate with them. A female who finds a male undesirable can simply rebuff his advances by calling on her male friends to chase him away, and can therefore enjoy exerting her reproductive skew. While infanticide is a reproductive strategy in males, it is costly for females, which would also explain why infanticide is a rare occurrence in olive baboons yet can be the principal cause of infant mortality in many other baboon subspecies: high-ranking females can simply rebuff a male threatening her infant, making infant-targeted aggression a reproductive disadvantage in olive baboons. This also explains the reason male olive baboons use infants as shields in aggressive encounters.<ref>Template:Cite journal</ref>
Males establish their dominance more forcefully than females.<ref name="Lang2" /> A male disperses,<ref name="Strier" /> or leaves his natal group and joins another group, after reaching sexual maturity.<ref name="Lang2" /> Adult males are very competitive with each other and fight for access to females.<ref name="Smuts1985" /> Higher dominance means better access to mating and earlier access to food, so naturally a great deal of fighting over rank occurs, with younger males constantly trying to rise in position.<ref name="Lang2" /> Because females stay with their groups their entire lives, and males emigrate to others, often a new male challenges an older one for dominance.<ref name="Lang2" /> Frequently, when older baboons drop in the social hierarchy, they move to another tribe.<ref name="Shefferly" /> The younger males who pushed them down often bully and harass them.<ref name="Shefferly" /> Older males tend to have more supportive and equal relationships than those of the younger males. The former may form coalitions against the latter.<ref name="Smut 1990">Template:Cite journal</ref>
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.<ref>Template:Cite journal</ref>
Reproduction and parenting
_suckling,_Semliki_Wildlife_Reserve.jpg){kind=link}
_with_juvenile.jpg){kind=link}
Females are sexually mature at seven to eight years old, and males at seven to 10 years.<ref name="Shefferly" /> The beginning of a female's ovulation is a signal to the males that she is ready to mate. During ovulation, the skin of the female's anogenital area swells and turns a bright red/pink.<ref name="Motluk">Template:Cite journal</ref> The swelling makes it difficult to move and increases the female's chance of microbial or parasitic infection.<ref name="Motluk" /> Females with more swollen anogenital areas reproduce while younger, produce more offspring per year, and those offspring have a better chance of surviving. These females also attract more males, and are more likely to cause aggressive fights between them.<ref name="Lang2" /> Olive baboons tend to mate promiscuously.<ref name="Lang2" /> A male forms a mating consortship with an estrous female, staying close to and copulating with her.<ref>Template:Cite journal</ref> 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.<ref name="Leigh">Template:Cite book</ref> 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.<ref name="Shefferly" /> Occasionally, male olive baboons monopolize a female for her entire period of probable conception.<ref name="Leigh" /> The male protects his female from being mated by other males during consortship.<ref>Template:Cite journal</ref>
Newborns have black natal coats and bright pink skin. Females are the primary caregivers of infants, but males also play a role.<ref name="Lang2" /> In its first few days, the infant may be unable to stay attached to its mother and relies on her for physical support. Its grasp grows stronger by its first week and it is able to cling to its mother's fur by itself.<ref name="Lang2" /> By two weeks, the infant begins to explore its surroundings for short periods, but stays near her. The distance the infant spends away from its mother increases the older it gets.<ref>Template:Cite journal</ref> In general, higher-ranking females are usually more relaxed parents than females of lower rank, which usually keep their offspring close to them.<ref name="Shefferly" /> This difference lasts for approximately the first eight weeks of an infant's life.<ref name="Shefferly" /> Olive baboons do not seem to practise co-operative parenting, but a female may groom an infant that is not hers. Subadult and juvenile females are more likely to care for another's young, as they have not yet produced offspring of their own.<ref name="Shefferly" /> One theory for why immature females tend to seek out infants is that they can prepare for their future roles as mothers.<ref name="Strier" /> Infant baboons born to first-time mothers suffer higher mortality than those born to experienced mothers, which suggests that prior experience in caring for infants is important.<ref name="Strier" /> Adult males in the groups also care for the infants, as they are likely to be related to them.<ref name="Packer1980" /> Males groom infants, reducing the amount of parasites they may have, and calm them when they are stressed. They may also protect them from predators, such as chimpanzees. Adult males exploit infants and often use them as shields to reduce the likelihood that other males will threaten them.<ref name="Packer1980">Template:Cite journal</ref>
Communication
Olive baboons communicate with various vocalizations and facial expressions. Throughout the day, baboons of all ages emit the "basic grunt".<ref name="Ransom1981">Ransom TW. (1981) Beach troop of the Gombe. East Brunswick (NJ): Assoc Univ Press Template:ISBN.</ref> 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.<ref name="Ransom1981" /> Other vocalizations include "broken grunting" (low-volume, quick series of grunts made during relatively calm aggressive encounters), "pant-grunts" (made when aggressive encounters escalate), "shrill barks" (loud calls given when potential threats appear suddenly), and "screams" (continuous high-pitch sounds responding to strong emotions).<ref name="Ransom1981" /> The most common facial expression of the olive baboon is "lipsmacking", which is associated with a number of behaviours.<ref name="Lang2" /> "Ear flattening", "eyes narrowed", "head shaking", "jaw-clapping", lipsmacking, and "tongue protrusion" are used when baboons are greeting each other, and are sometimes made with a "rear present".<ref name="Ransom1981" /> "Eyebrow raising", "molar grinding", "staring", and "yawning" are used to threaten other baboons.<ref name="Lang2" /> A submissive baboon responds with displays such as the "fear grin", the "rigid crouch", and "tail erect".<ref name="Ransom1981" />
Diet
One major reason for its widespread success is that the olive baboon is omnivorous and like other baboons, will eat practically anything.<ref name="Lang" /> As such, it is able to find nutrition in almost any environment and is able to adapt with different foraging tactics.<ref name="Whiten1991" /> For instance, the olive baboon in grassland goes about finding food differently from one in a forest.<ref name="Lang" /> The baboon forages on all levels of an environment, above and beneath the ground and in the canopy of forests.<ref name="Whiten1991">Template:Cite journal</ref> 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.<ref name="Whiten1991" />
The diet typically includes a large variety of plants, and invertebrates and small mammals, as well as birds.<ref name="Skelton">Template:Cite webTemplate:Dead link</ref> The olive baboon eats leaves, grass, roots, bark, flowers, fruit, lichens, tubers, seeds, mushrooms, corms, and rhizomes.<ref name="Skelton" /> Corms and rhizomes are especially important in times of drought, because grass loses a great deal of its nutritional value.<ref name="Skelton" /> In dry, arid regions, such as the northeastern deserts, small invertebrates like insects, grubs, worms, spiders, and scorpions fill out its diet.<ref name="Skelton" />
The olive baboon also actively hunts prey, such as small rodents, birds and other primates.<ref name="Lang" /> Its limit is usually small antelope, such as Thomson's gazelle, but will also kill sheep, goats, and chickens from farms, which may amount to around one third of its food from hunting.<ref name="Lang" /> Hunting is usually a group activity, with both males and females participating.<ref name="Lang" /> This systematic predation was apparently developed recently.<ref name="Strum">Template:Cite journal</ref> In a field study, such behaviour was observed as starting with the males of one troop and spreading through all ages and sexes.<ref name="Strum" />
In Eritrea, the olive baboon has formed a symbiotic relationship with that country's endangered elephant population. The baboons use the water holes dug by the elephants, while the elephants use the tree-top baboons as an early warning system.<ref>Template:Cite magazine</ref>
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.<ref name=iucn /> Competition and disease have possibly led to fewer baboons in closed forests. Like most other baboon species, it is routinely exterminated as a pest for crop raiding and small livestock predation.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
References
External links
Template:Commons Template:Wikispecies
Template:C.Cercopithecinae nav Template:Taxonbar Template:Authority control