The hamadryas baboon (Papio hamadryas ; ; ) is a species of baboon within the Old World monkey family. It is the northernmost of all the baboons, being native to the Horn of Africa and the southwestern region of the Arabian Peninsula. These regions provide habitats with the advantage for this species of fewer natural predators than central or southern Africa where other baboons reside. The hamadryas baboon was a sacred animal to the ancient Egyptians and appears in various roles in ancient Egyptian religion, hence its alternative name of 'sacred baboon'.
Description
The hamadryas baboon shows differences in coloration among adults with males having a pronounced silver-white mane and mantle, which they develop at around the age of ten years, while the females are capeless and brown all over and have reddish to dark brown faces. They are also sexually dimorphic in size, and males are nearly twice as large as females. The tail adds a further to the length, and ends in a small tuft. Infants are very dark brown or black in coloration and lighten after about one year. Hamadryas baboons reach sexual maturity at about four years for females and between five and seven years for males.
Behaviour and ecology
thumb|The hamadryas baboon eats fruit in captivity, although it is not a regular part of its diet in the wild.
The hamadryas baboon's range extends from the Red Sea in Eritrea to Ethiopia, The hamadryas baboon lives in arid areas, savannas, and rocky areas, requiring cliffs for sleeping and finding water. Like all baboons, the hamadryas baboon is omnivorous and is adapted to its relatively dry habitat. During the wet seasons, the baboon feeds on a variety of foods, including blossoms, fruits, seeds, grasses, rhizomes, corms, wild roots, tubers, bark, tree gums and leaves from acacia trees. During the dry season, the baboons eat leaves of the Dobera glabra and sisal leaves. Hamadryas baboons also eat eggs, insects, spiders, worms, scorpions, reptiles, birds, and small mammals, including antelope. Two or more harems unite repeatedly to form clans. Within clans, males are close relatives of one another and have an age-related dominance hierarchy. Bands are the next level. Two to four clans form bands of up to 400 individuals which usually travel and sleep as a group. Bands may fight with one another over food or territory, and the adult male leaders of the units are the usual combatants. Several bands may come together to form a troop, usually at sleeping cliffs. Males sometimes raid harems for females, resulting in aggressive fights. Many males succeed in taking a female from another's harem, called a "takeover". Visual threats are usually accompanied by these aggressive fights. This would include a quick flashing of the eyelids accompanied by a yawn to show off the teeth. As in many species, infant baboons are taken by the males as hostages during fights. However, males within the same clan tend to be related and respect the social bonds of their kin. In addition, females demonstrate definite preferences for certain males, and rival males heed these preferences. The male may also abduct a young female by force. However, later studies show female baboons retain close associations with at least some female kin. Females do most of the parenting. They nurse and groom the infant and one female in a unit may groom an infant that is not hers. Like all baboons, hamadryas baboons are intrigued by infants and give much attention to them. Dominant male baboons prevent other males from coming into close contact with their infants. They also protect the young from predators. The dominant male tolerates the young and will carry and play with them. When males reach puberty, they show a playful interest in young infants. Using implanted data loggers and simulated desert conditions, researchers found baboon internal temperatures increased significantly with water deprivation. Hamadryas baboons do this by increasing albumin synthesis.
thumb|upright|Captive male at [[Tierpark Hellabrunn, Germany]]
Threats and conservation
Transformation of field and pastureland represents the main threat to the hamadryas baboon; its only natural predators are the striped hyena, spotted hyena, and a diminishing number of African leopards that can still be found in the same area of distribution. Grey wolves are predators of Hamadryas baboons in Saudi Arabia. The IUCN Red List listed this species as "least concern" in 2008.