Common ostrich
Common ostriches usually weigh from , or as much as two adult humans. The Masai ostriches of East Africa ("S. c. massaicus") averaged in males and in females, while the nominate subspecies, the North African ostrich ("S. c. camelus"), was found to average in unsexed adults. Exceptional male ostriches (in the nominate subspecies) can weigh up to . At sexual maturity (two to four years), male common ostriches can be from in height, while female common ostriches range from tall. New chicks are fawn in colour, with dark brown spots. During the first year of life, chicks grow at about per month. At one year of age, common ostriches weigh approximately . Their lifespan is up to 40–45 years.
Common ostrich
With their acute eyesight and hearing, common ostriches can sense predators such as lions from far away. When being pursued by a predator, they have been known to reach speeds in excess of , and can maintain a steady speed of , which makes the common ostrich the world's fastest two-legged animal. When lying down and hiding from predators, the birds lay their heads and necks flat on the ground, making them appear like a mound of earth from a distance, aided by the heat haze in their hot, dry habitat.