Olive Baboon

TAXONOMY

Suborder: Anthropoidea
Infraorder: Catarrhini
Superfamily: Cercopithecoidea
Family: Cercopithecidae
Subfamily: Cercopithecinae
Genus: Papio
Species: anubis

Other names: Papio hamadryas anubis; anubis baboon; babouin anubis (French); papi?n oliva (Spanish); olivbabian (Swedish)

MORPHOLOGY

Olive baboons have a greenish-grey coat covering their bodies. The individual hairs are green-grey with rings of black and yellowish-brown, giving the coat a multi-color appearance from up-close (Rowe 1996; Groves 2001). Infants are born with a black natal coat that changes to the adult coloration as they age. Adult males have long hair forming a mane from the top of their heads through their shoulders and which gradually shortens down the back (Groves 2001). The skin on their faces, ears, and ischial callosities is dark grey to black and covered with a very fine fur and they have a salt and pepper wreath of fur around their faces. Olive baboons have long, pointed muzzles rather than the flat faces characteristic of other primates, including humans, and because of their quadrupedal stance and locomotion, they appear quite dog-like (Nagel 1973). Their tails are long, between 380 and 584 mm (1.25 and 1.92 ft), and are held up and away from the rump for about a quarter of the total length, and then drop suddenly, giving the appearance that the tail is broken (Groves 2001). Like other cercopithecines, olive baboons have cheek pouches, specialized sacs on the inside of their cheeks than can be used for storing food as they forage (Rowe 1996).

Males and females are sexually dimorphic, with the males being about twice as large as females. The average height for captive and wild males is about 700 mm (2.30 ft) and females measure about 600 mm (1.97 ft) (Coelho 1985; Eley et al. 1989). Wild male olive baboons weigh 24 kg (52.9 lb), on average and wild females weigh 14.7 kg (32.4 lb) on average (Strum 1991). Where they live close to agricultural production and can raid crops, supplementing their natural diets with fruits, vegetables, and grains grown by local people, the average weights are slightly higher. Crop-raiding males weigh around 27.4 kg (60.4 lb) and females weigh 15.6 kg (34.4 lb) (Strum 1991). Captive olive baboons weigh more than their wild counterparts, with the weight of captive males averaging 29 kg (63.9 lb) and females averaging 17 kg (37.5 lb) (Coelho 1985).

RANGE

Olive baboons are widespread throughout equatorial Africa and are found in 25 countries (www.redlist.org). From the west coast of Africa moving eastward, olive baboons are found in Guinea, Mali, Mauritania, Sierra Leone, C?te d'Ivoire, Burkina Faso, Ghana, Togo, Benin, Nigeria, Niger, Chad, Central African Republic, Cameroon, Sudan, Ethiopia, Eritrea, and Somalia. The range of olive baboons extends southward into Uganda, Kenya, Tanzania, Rwanda, Burundi, Democratic Republic of Congo, and Congo (Groves 2001). Until 2001, a free-ranging population of olive baboons could be found in Spain, but they have subsequently been captured and transferred to zoos. This group of Spanish baboons was established when a group of 60 olive baboons escaped from a safari park and began ranging free on a governmental ranch in 1972 (Gil Burmann et al. 2002).

In the westernmost part of their natural range, in Guinea and Mali, olive baboons overlap with guinea baboons (Papio papio) but hybridization between the two species has not been studied. In the Awash River Valley in central Ethiopia, their range overlaps with hamadryas baboons (P. hamadryas) and the two species interbreed, forming a hybrid zone (Nagel 1973). These hybrid crosses have intermediate physical appearances of both species. There are other areas of overlap between olive and hamadryas baboons in Ethiopia, but the hybrids of the Awash Valley have been most closely studied (Nagel 1973). Olive baboons also hybridize with yellow baboons (P. cynocephalus) in Kenya and Tanzania, most notably in Amboseli National Park, Kenya. Historical and long-term crossbreeding of these two species may have contributed to the formation of the subspecies P. cynocephalus ibeanus (Alberts &Altmann 2001).

P. anubis range (in red)

Research on wild, free-ranging olive baboons has been ongoing since 1978 at Masai-Mara National Reserve, Kenya by Robert Sapolsky and his colleagues. Robert Harding, followed by Shirley Strum and her colleagues at the Gilgil Baboon Project, also have added greatly to the knowledge about wild olive baboons in Kenya by studying them at Kekopey and Chololo Ranches, near Gilgil, Kenya since 1970. Ryne Palombit has also been studying baboons continuously since 2000 on Laikipia Plateau in Kenya. Gombe Stream National Park, Tanzania was made famous by Jane Goodall's research on chimpanzees (Pan troglodytes), but olive baboons have also been studied here. The Southwest National Primate Research Center in Texas is home to the world's largest captive baboon colony and most of the baboons studied there are olive baboons. Research on olive baboons has focused on genetic mapping and using them as a model for understanding the physiological changes associated with aging in humans (www.snprc.org).

HABITAT

Olive baboons live in a variety of habitats across their broad range. Baboons are generally characterized as savanna species, inhabiting open grassland near wooded areas (Rowell 1966). While olive baboons do inhabit grassland in much of their range, they are also found in moist, evergreen forests and near areas of human habitation and cultivation (Naughton-Treves et al. 1998). At Gilgil, Kenya, where olive baboons have been studied since the early 1970s, the habitat is open grassland with few trees. Kekopey and Chololo Ranches are situated in the central Rift Valley and are characterized by deep valleys that run parallel and which are separated by rocky cliffs. In these valleys, grassy plains are interspersed with occasional patches of shrub and only a few trees can survive in the rocky soils (Harding 1976). Rainfall is concentrated during a period of several weeks in November, and for a longer period stretching from April to June. Mean annual rainfall is between 595 and 756 mm (1.95 and 2.48 ft). The warmest months of the year are from December through March and the average daily temperature ranges from 10.6? and 25.5? C (51.1? and 77.9? F) (Harding 1976). Another site where baboons in Kenya have been studied is at the Laikipia Plateau in the central part of the country. Situated at an altitude of 1600 to 1700 m (5249 to 5577 ft), Laikipia consists of dry woodland and grassland dotted with stands of trees and thick shrubbery (Barton et al. 1992). Most of the trees are Acacia species and the understory of the woodland is made up of grasses, sedges, and xerophytic species (Barton &Whiten 1993). Additionally, outcroppings of steep rocky slopes and large boulders with sparse vegetation characterize the plateau and are known as kopjes. Mean annual rainfall is 549 mm (1.90 ft) and rainfall is concentrated in two rainy seasons, from March to June and November to December. Seasonal streams cut through the grassland; damming the streambeds has led to permanent waterholes. Average daily temperatures range from 12.4? to 37.2? C (54.3? to 99.0? F) and the hottest month of the year is February (Barton et al. 1992; Barton &Whiten 1993).

Olive baboons are also found in Ethiopia. In the Bole Valley, olive baboons range from the valley bottom, found at an altitude of 1700 m (5577 ft) to the plateau which rises over the valley floor to an altitude of 2300 m (7546 ft) (Dunbar & Dunbar 1974). The baboons utilize all habitats found from the valley floor to the plateau. In the riverbed, the lowest point of Bole Valley, gallery forest abounds and trees up to 30 m (98 ft) in height grow with a thick understory of shrubs and grasses. Moving up the slopes of the valley, the trees give way to more open grassland interspersed with thickets and eventually, as the altitude increases, open grassland dominates the environment. At the top of the plateau, stands of trees and thickets are scattered across the grassland (Dunbar & Dunbar 1974). The rainy season lasts from July to early September and the dry season from mid-September to June, with an average of 2000 mm (6.56 ft) of rain falling each year. Daytime temperatures remain around 35? C (95? F) throughout the year (Dunbar & Dunbar 1974). Baboons have been intensely studied elsewhere in Ethiopia at the Awash River Valley. Along the Awash River, gallery forest dominates the landscape, with the canopy remaining less than 20 m (65.6 ft) in height and with a thin understory (Aldrich-Blake et al. 1971). Moving away from the river, the landscape transitions into thorny scrub with areas of trees. A dormant volcano, Mount Fantalle, has been recently active, creating lava fields and cliffs mixed with bare rock and dry, flat areas bordering the savanna. This area of Ethiopia is considered arid, with short rains falling in February and March and another, longer rainy season lasting from July to September (Aldrich-Blake et al. 1971). Average annual rainfall ranges between 533 and 774 mm (1.75 and 2.54 ft), but some years can be unusually dry. Average daily temperatures range between 18 and 31? C (64.4 and 87.8? F), but on the lava fields can be much higher (Aldrich-Blake et al. 1971).

In neighboring Eritrea, olive baboons live in arid and moist lowlands below 900 m (2953 ft) characterized by riverine forest bordered by savanna. Average rainfall in their Eritrean range is 544 mm (1.78ft) per year (Zinner et al. 2001). In Pendjari National Park, Benin, surveys of olive baboons reveal that they too inhabit gallery forests and savanna interspersed with open woodland (Sinsin et al. 2002). The climate is dry, but rains fall starting in April or May and last until October. Most rain falls in August and September and the average annual rainfall is 1000 mm (3.28 ft) per year, but the distribution over time and space is highly variable. The average temperatures range from 12 to 40? C (53.6 to 104? F) and the hot climate, coupled with variable rainfall patterns leads to periods of drought (Sinsin et al. 2002). In Ghana, olive baboons also live in savanna woodland where thickets and dry forest intersperse open grassland. In the Shai Hills, rocky outcroppings and hills rise above the grassland and small trees and wooded areas are found on plateaus (Lieberman et al. 1979). At 26.4? C (79.5? F), the average temperature is moderate. Small amounts of rain fall during the two rainy seasons from March to July and September to November, and average annual rainfall is 733 mm (2.40 ft) (Lieberman et al. 1979).

Not all olive baboons live in open woodland bordered by savanna. In many of their range countries, they live in evergreen tropical forests. In Uganda, both types of habitat exist and olive baboons utilize each. At Queen Elizabeth National Park, situated near the border of Democratic Republic of Congo, where olive baboons are also found, the habitat is characterized by dense forest surrounding the Ishasa River which slowly transitions from forest edge to coarse wet grass, then short grass with sandy areas, to low bush, and then to open grassland dotted with solitary trees and tall shrubs and bushes (Rowell 1966). At Kibale National Park, in western Uganda, olive baboons live in moist, evergreen forest bordered by swamp, grassland thickets, and secondary forests. Around the park, local families have cleared forest for subsistence agriculture. With a variety of cultivated crops growing near their habitat, olive baboons have become notorious crop-raiders, supplementing their diets with maize and bananas (Naughton-Treves et al. 1998). Across the park, rainfall varies from 1100 to 1600 mm (3.61 to 5.25 ft) per year and annual average daily temperature ranges from 23.3 to 24.2? C (73.9 to 75.6? F) (Naughton-Treves et al. 1998).

ECOLOGY

Olive baboons are ecologically flexible in that they consume a wide variety of foods and can live in a variety of habitats, but nonetheless they are selective about their diet choice and habitat usage (Whiten et al. 1991; Barton et al. 1992). Olive baboons can be found in habitats ranging from desert to montane forest. One reason they are able to adapt to these varying habitats could be their flexibility in foraging strategies and ability to extract food and nutrients from almost all strata of the environment (Whiten et al. 1991). They find food on the ground, in the trees, and underground. On the ground, they forage in the grass or in thickets of savanna woodland, they forage in trees and find food at higher levels of the canopy, and finally, they dig up subterranean foods (Whiten et al. 1991). Baboons are omnivores and consume a huge variety of items including roots, tubers, corms, fruits, leaves, flowers, buds, seeds, bark, exudates, cacti, grasses, insects, birds, bird eggs, and vertebrates (including other primates) up to the size of a small antelope (Rowell 1966; Dunbar & Dunbar 1974; Harding 1976; Whiten et al. 1991; Hassan 2001). Olive baboons are generally opportunistic hunters, capturing prey as they come across it, but at Gilgil, Kenya, olive baboons exhibit simple and complex hunting patterns (Strum 1981). For baboon predation to be considered simple hunting, it requires active searching and stalking or chasing of the prey, usually a small antelope, ground-dwelling bird, or other small mammal. Thomson's gazelles make up 33% of the prey eaten by olive baboons (Strum 1983). Simple hunting involves only one baboon and the pursuit of the prey lasts less than 10 minutes and occurs within 300 m (.186 mi) of the rest of the baboon troop (Strum 1981). Complex hunting involves more than one baboon, a pursuit of prey lasting longer than 10 minutes and ranging greater distances from the group during the chase, between 300 and 4000 m (.186 and 2.49 mi). Both male and female olive baboons hunt (Strum 1981). In the relatively richer forest environments where they are found, olive baboons rely heavily on fruits compared to seeds and grasses consumed by savanna-living baboons (Ransom 1981).

In many areas of their range where human populations are increasing, olive baboons raid agricultural crops for food and feed on garbage and human refuse (Forthman Quick 1986; Eley et al. 1989; Naughton-Treves et al. 1998). Feeding close to human populations influences group behavior among olive baboons and may also influence social structure (Forthman Quick 1986). At Gilgil, the conflict between farmers and baboons became so intense that by 1984, more than 130 baboons were trapped and translocated in an attempt to appease farmers and save the baboons from persecution (Strum 1987).

Rainfall is directly correlated with food availability in many habitats. In savanna areas, the food availability is highest near the end of the rainy season and gradually decreases in abundance as the dry season continues (Barton et al. 1992). During the rainy season, fruit, young leaves, and flowers are abundant and important foods for olive baboons. As the dry season progresses, these foods become scarce and baboons must switch to other resources (Barton et al. 1992). One way that olive baboons deal with the scarcity of food is to utilize subterranean food sources such as roots, tubers, and corms (Barton & Whiten 1993). Olive baboons are good diggers and use their hands to unearth the roots of plants (Nagel 1973). Seeds are also an important food resource during the dryer times of the year (Barton et al. 1992). In Uganda, olive baboons do not experience the limited availability of food plants seen in the savanna portions of their range. Plants follow an annual cycle of flowering and fruiting, but there are no seasons in which a wide variety of food plants are not available (Rowell 1966).

In the Bole Valley, Ethiopia, olive baboons have home range sizes between.745 and 1.12 km² (.288 and.432 mi²) and range between .3 and 2.0 km (.186 and 1.24 mi) per day (Dunbar & Dunbar 1974). In one study at Laikipia Plateau, Kenya, home range and day length sizes were much larger than in the Bole Valley. Home range size was 43.8 km² (16.9 mi²) and the average distance traveled per day was 5.64 km (3.50 mi) (Barton et al. 1992). The drastic differences in habitat use can be partly attributed to group size. As group size increases, so does home range size and day range length (Barton et al. 1992). The study population used by Barton et al. (1992) numbered about 100 olive baboons while Dunbar and Dunbar (1974) studied seven groups ranging in size from 15 to 24 animals. This relationship exists because larger groups experience increased competition for resources such as food; therefore the area covered each day and subsequently the home range within which the group forages increases to accommodate the needs of a larger number of animals (Barton et al. 1992). At Gilgil, Kenya, the home range size of a group of 49 baboons was 19.7 km² (7.60 mi²) but 75% of their time was spent in a core area about 25% of the total size of the home range (Harding 1976). The average day length for the study group at Gilgil was around 5 km (3.11 mi), with the shortest distance traveled being 2.2 km (1.37 mi) and the longest day journey being 7.8 km (4.85 mi) (Harding 1976). At Ishasa, Uganda, where olive baboons spend up to 60% of their time in the rich, forested areas, home range size ranges between 3.88 and 5.18 km² (1.5 and 2 mi²) and day range length can be as short as a few hundred meters and up to 2.4 km (1.5 mi) (Rowell 1966). At Gombe, Tanzania, another forested site where olive baboons have been studied, home ranges average 3.88 to 5.18 km² (1.5 to 2 mi²) (Ransom 1981).

As seasonal rainfall influences food availability, it in turn affects home range size and daily ranging patterns (Nagel 1973; Harding 1976; Ransom 1981; Barton et al. 1992). Daily activity patterns are also variable, depending on the season and climatic conditions. Departure from the sleeping site, the time spent traveling, the maximum distance traveled from the sleeping site, the number and length of resting and feeding periods, and the distance covered per day are all variable from one day to the next and from one group of baboons to the next (Nagel 1973). The general pattern observed is a period of socializing after waking, moving from the sleeping site and feeding, resting, and then alternating feeding and resting until late afternoon at which time the group travels back to the sleeping site. Most social activities occur during the periods of rest throughout the day (Strum 1987). The home ranges of several groups of baboons often overlap, and when groups come into contact with one another, the larger group displaces the smaller group or the two groups largely ignore each other (Aldrich-Blake et al. 1971; Smuts 1985). In many cases, the adult males within the group with chase the adult females of their troop away from the other troop. They threaten females presumably to reduce the contact of group females with outside males (Packer 1979a).

Olive baboons seek sleeping refuges in trees or on rocky cliffs, depending on availability (Aldrich-Blake et al. 1971; Nagel 1973; Harding 1976; Hamilton 1982). Open cliffs, free of extensive woody vegetation and with near-vertical slopes are preferred as nighttime sleeping spots (Hamilton 1982). When cliffs are not available, olive baboons prefer emerging trees, those that protrude from the surrounding canopy, to any other tree sleeping site such as closed canopy, where trees are close enough to each other that baboons can transverse the canopy without coming to the ground, or open woodland, where trees are separated to the degree that baboons must come to the ground to get into a neighboring tree (Hamilton 1982). One reason they are selective about sleeping sites is to increase protection from predators. Some of the known predators of baboons include large cats, which have a difficult time scaling rocky walls because they cannot find holdings for their paws as well as baboons can for their hands and feet, explaining why cliffs and rocky ledges are preferred to trees when both are available (Hamilton 1982). Besides felids such as lions, leopards, and servals, other potential predators of olive baboons include wild dogs, hyenas, chimpanzees, crocodiles, and raptors, which are a more serious threat to juveniles and infants (Rowell 1966; Nagel 1973; Harding 1976; Barton et al. 1996). Domestic dogs are also potentially serious predators of baboons (Smuts 1985).

Info from:http://pin.primate.wisc.edu/factsheets/entry/olive_baboon