The strong and robust Hamadryas baboons (Papio hamadryas) belong to Old World monkeys. They are highly intelligent animals. Mature males of this species are identified by their silver manes and pink faces. In Ancient Egypt, they were considered representatives of the Egyptian god of learning, hence, they are otherwise known as Secret baboons. Nowadays, these animals are extinct in Egypt and are currently found in Ethiopia, Somalia, Saudi Arabia, and Yemen.
Apart from the striking sexual dimorphism (males are nearly twice as large as females, which is common to most baboons) this species also shows differences in coloration among adults. Adult males have a pronounced cape (mane and mantle), silver-white in color, which they develop around the age of ten, while the females are capeless and brown all over. Their faces range in color from reddish to tan to a dark brown. Infants are very dark brown or black in coloration and lighten after about one year.
These primates are found from the Red Sea in Eritrea to Ethiopia, Djibouti, Somalia as well as Yemen and Saudi Arabia in the southwestern part of the Arabian Peninsula. Preferred types of habitat are sub-deserts, steppes, alpine grass meadows, plains, and short-grass savannahs. The Hamadryas baboons always remain close to water. Hence, during the wet season, some populations move to mountain areas.
Hamadryas baboons lead a diurnal lifestyle, being active by day and sleeping by night. Although they are generally terrestrial, they prefer sleeping in trees or cliffs. The multi-level social system of these primates is rather complex: Hamadryas baboons form so-called one-male units (OMUs), consisting of 1-9 females and their young that are aggressively herded, controlled, and guided by a single leading male. Usually, females of an OMU compete to groom and stay close to the leading male. On the other hand, leading males of various OMUs are often related. They closely associate, gathering into social units known as 'clans'. Each group also contains a subordinate, "follower" male, which is typically related to the dominant male. Group members engage in collective activities such as sleeping, traveling, and foraging. Several OMUs occasionally form bands - groups of 30-90 individuals. Multiple such bands, in turn, may sleep in the same area, forming troops - aggregations of up to several hundred Hamadryas baboons.
As an omnivore, the Hamadryas baboon consumes food of both animal and plant origin such as fruits, tree gums, acacia seeds, acacia flowers, seeds, grass, rhizomes, corms, roots, tubers as well as small vertebrates, insects, and small mammals, including antelope.
These primates have a polygynous mating system. The dominant male of OMU mates with the females of the group. Hamadryas baboons don't have a breeding mating season. Instead, they breed year-round with peak a period, occurring in May-July. Meanwhile, the population in Ethiopia typically breeds in November-December. Females produce offspring at intervals of 15-24 months. The gestation period lasts for 170-173 days, yielding one infant, which remains with its mother for the first few months of its life. The weaning process takes about 9 months, lasting from 6 to 15 months. The Hamadryas baboons are independent at around 2 years old, after which males continue living with their natal clan, whereas females often move between clans and bands. The age of reproductive maturity is 5-7 years old in males and 4 years in females.
The Hamadryas baboons are locally hunted for their skin and trapped for medical research. These animals are also killed as pests due to destructing crops. In some parts of their range, these primates suffer from the loss of their natural habitat and come into serious conflict with humans as a result of overgrazing, agricultural development, and irrigation projects.
According to IUCN, the Hamadryas baboon is abundant and widespread throughout its range but no overall population estimate is available. However, Djibouti, its total population is estimated to be around 2,000 animals. Overall, Hamadryas baboons are classified as Least Concern (LC) and their numbers are increasing today.
On one hand, due to their habit of digging for tubers, roots, rhizomes, and corms, Hamadryas baboons probably contribute to the soil aeration within their range. On the other hand, they may act as important seed dispersers of plants that they consume. Additionally, these primates form an irreplaceable link in the food chain of their habitat: by feeding upon various plants and animals, they get certain nutrients that later become available to larger animals, which feed upon Hamadryas baboons.