Males are larger and have massive features and a well-developed silver shaggy cape or mane. Coat of male ashy gray, slightly washed with brown. Female and young fulvous brown, without mane. Face is reddish-pink with a very long muzzle in the same line as the brain case. Callosities highly developed and surrounded by bright reddish pink skin.
Females exhibit monthly genital swelling.
Inhabits plains and rocky hill country in Ethiopia and Somalia in Africa, and Saudi Arabia and Yemen on the Arabian Peninsula. They are found from sea level to 2600 meters. In parts of Arabia, they are becoming increasingly dependent on raiding crops and garbage dumps. Usually drink about midday. The Hamadryas baboon is socially and structurally distinct from other species of baboon.