Hamadryas Baboon

About the hamadryas baboon

The hamadryas baboon is a species of Old World monkey and the northernmost of all baboons, native to the Horn of Africa and the southwestern Arabian Peninsula. Its range in the Horn and in Arabia gives it fewer natural predators than the baboon species living in central or southern Africa. The animal held religious significance in ancient Egypt, where it was considered sacred, and it is sometimes still called the sacred baboon as a result.

Adult hamadryas baboons show marked differences between the sexes. Males develop a striking silver-white mane and mantle at around ten years of age, while females stay capeless and brown all over, with reddish to dark brown faces. The species is also strongly dimorphic in size: males can reach a body length of up to 80 cm (31 in) and weigh 20–30 kg (44–66 lbs), while females measure 40–45 cm (16–18 in) long and weigh 10–15 kg (22–33 lbs). In both sexes the tail adds a further 40–60 cm (16–24 in) and ends in a small tuft. Infants are born very dark brown or nearly black and lighten in color after about a year. Females reach sexual maturity around four years of age, males somewhat later, between five and seven years.

The species lives in arid country, savanna, and rocky terrain, and depends on cliffs for sleeping and for access to water. Its range runs from the Red Sea coast of Eritrea through Ethiopia, Djibouti, and Somalia, and it is also found in the Sarawat Mountains of southwestern Arabia, in both Yemen and Saudi Arabia. It no longer occurs in Egypt, where it is considered locally extinct.

Behavior and diet

Hamadryas baboons are omnivorous and well adapted to their dry habitat. During the wet season they eat a wide range of plant foods, including blossoms, fruits, seeds, grasses, rhizomes, corms, wild roots, tubers, bark, tree gums, and acacia leaves. In the dry season, when those foods are scarce, they turn to the leaves of Dobera glabra and sisal. They also eat eggs, insects, spiders, worms, scorpions, reptiles, birds, and small mammals, including antelope. Their drinking habits shift with the season too: during wet months they rarely have to travel far for water, but in the dry season they visit as many as three permanent waterholes, resting there in midafternoon and sometimes digging their own drinking holes nearby.

Social life is organized into an unusual four-level, strictly patriarchal system. The base unit is a "one-male unit" or harem, made up of one male and up to ten females, sometimes joined by a younger "follower" male related to the leader. Two or more harems combine into clans of related males with an age-based dominance hierarchy. Clans in turn combine into bands of up to 400 animals that travel and sleep together, and several bands may gather into a troop at shared sleeping cliffs. Males guard their harems closely, herding females with visual threats — a quick flash of the eyelids paired with a yawn that shows off the teeth — and sometimes grabbing or biting females that wander. Rival males may attempt "takeovers" of another male's females, and young "follower" males sometimes build their own harems by maneuvering immature females into following them.

Breeding is not seasonal. The dominant male of a one-male unit does most of the mating, though other males occasionally manage to mate as well. Females handle nearly all parenting, nursing and grooming infants, and even grooming infants that are not their own; the dominant male tolerates and sometimes carries and plays with the young while also protecting them from predators. When a new male takes over a female, she develops sexual swellings, which may help prevent the new male from killing the previous male's offspring.

Range and habitat

The hamadryas baboon's native range runs from the Red Sea coast of Eritrea across Ethiopia, Djibouti, and Somalia, and extends into the Sarawat Mountains of southwestern Arabia in Yemen and Saudi Arabia. It has been extirpated from Egypt. The species favors arid areas, savannas, and rocky terrain, and it needs cliffs both for sleeping at night and for access to water. Several bands may also come together to form a troop, usually at these sleeping cliffs. Habitat suitability shifts with the seasons: during the rains, food and water are both close at hand, while the dry season pushes baboons toward specific plant species and a small number of permanent waterholes.

Conservation status

The hamadryas baboon is listed as Least Concern on the IUCN Red List. It was first given that rating in 2008, and the current assessment dates from 2019.

There are no major range-wide threats at present. The main local concern is the conversion of fields and pastureland for agricultural expansion and irrigation projects, which can remove habitat in parts of its range. Natural predators include striped and spotted hyenas, a dwindling number of African leopards, and gray wolves in Saudi Arabia.

The species occurs in the proposed Yangudi Rassa National Park, the Harar Wildlife Sanctuary and several wildlife reserves in the lower Awash valley and in northern Eritrea, which give it some protected habitat.