The ostrich is typical of a group of flightless birds called ratites. Ostrich populations differing slightly in skin colour, size, and egg features formerly were considered separate species, but now they are considered to be merely races of Struthio camelus. Ostriches live mainly on vegetation but also take some animal food, mainly insects; they can go without water for long periods. Breeding males emit lionlike roars and hisses as they fight for a harem of three to five hens.
