The diet of the Ostrich mainly consists of plant matter, though it also eats insects. It lives in nomadic groups which contain between five and fifty birds. When threatened, the Ostrich will either hide itself by lying flat against the ground, or will run away. If cornered, it can attack with a kick from its powerful legs. Mating patterns differ by geographical region, but territorial males fight for a harem of two to seven females.
The Ostrich is farmed around the world, particularly for its feathers, which are decorative and are also used for feather dusters. Its skin is used for leather and its meat marketed commercially.
Ostriches usually weigh from 63 to 130 kilograms (140–290 lb), with exceptional male Ostriches weighing up to 155 kilograms (340 lb). The feathers of adult males are mostly black, with white primaries and a white tail. However, the tail of one subspecies is buff. Females and young males are greyish-brown and white. The head and neck of both male and female Ostriches is nearly bare, with a thin layer of down.. The skin of the females neck and thighs is pinkish gray, while the male's is blue or gray dependent on subspecies.
The long neck and legs keeps their head 1.8 to 2.75 metres (6 to 9 ft) above the ground, and their eyes are said to be the largest of any land vertebrate – 50 millimetres (2.0 in) in diameter; they can therefore perceive predators at a great distance. The eyes are shaded from sun light falling from above.
Their skin is variably coloured depending on the sub-species. The male tarsus has red horn plates, while the female's are black. The strong legs of the Ostrich, like those of other birds, are scaled and unfeathered. The bird has just two toes on each foot (most birds have four), with the nail on the larger, inner toe resembling a hoof. The outer toe lacks a nail. The reduced number of toes is an adaptation that appears to aid in running. The wings reach a span of about 2 metres (6 ft 7 in) and are used in mating displays and to shade chicks. The feathers lack the tiny hooks that lock together the smooth external feathers of flying birds, and so are soft and fluffy and serve as insulation. They have 50-60 tail feathers, and their wings have 16 primary, four alular and 20-23 secondary feathers. The Ostrich's sternum is flat, lacking the keel to which wing muscles attach in flying birds. The beak is flat and broad, with a rounded tip. Like all ratites, the Ostrich has no crop, and it also lacks a gallbladder. They have three stomachs, and the caecum is 28 inches (71 cm) long. Unlike all other living birds, the Ostrich secretes urine separately from feces. They also have unique pubic bones that are fused to hold their gut. Unlike most birds the males have a copulatory organ, which is retractable and 8 inches (20 cm) long. Their palate is different than other ratites, in that the sphenoid and palatal bones are unconnected.
At sexual maturity (two to four years), male Ostriches can be from 1.8 to 2.8 metres (5 ft 11 in to 9 ft 2 in) in height, while female Ostriches range from 1.7 to 2 metres (5 ft 7 in to 6 ft 7 in). During the first year of life, chicks grow about 25 centimetres (10 in) per month. At one year of age, Ostriches weigh around 45 kilograms (100 lb).