The ostrich is the world’s largest living bird by height and mass.
The common ostrich is a flightless bird native to much of Africa. Adult males can stand nearly 2.8 metres tall and may weigh more than 100 kilograms, making the species larger than any other living bird. Its long neck and legs account for much of its height.
Ostriches cannot fly because their bodies are too large and their wings are not suited to powered flight. Instead, they are specialized runners. Their long legs allow them to cover ground rapidly, and each foot has two toes, an unusual feature among birds.
The emu and cassowaries are also large flightless birds, but they are shorter and lighter. The extinct elephant birds of Madagascar were larger than modern ostriches, but they are not living species.