ratites

Ratites are a group of large, flightless birds within the clade Palaeognathae. They are characterized by a flat sternum without a keel, relatively small wings, and strong legs adapted for running. Most are ground-dwellers with herbivorous or omnivorous diets. They are distributed mainly in the Southern Hemisphere and include the ostrich (Struthio camelus) of Africa, the emu (Dromaius novaehollandiae) of Australia, the cassowaries (genus Casuarius) of New Guinea and northern Australia, and rheas (genus Rhea) of South America. The extinct moa of New Zealand and elephant birds of Madagascar were also ratites.

Historically, ratites were treated as a single natural group of flightless birds. However, modern phylogenetics shows that tinamous, which can fly, are their closest living relatives, and that flightlessness has evolved independently in several ratite lineages; thus ratites are not a strictly monophyletic group.

Ratites typically nest on the ground and lay large eggs. Diets vary from grasses and seeds to fruits and invertebrates, depending on species and habitat. Reproduction and parental care differ among taxa, with some species showing substantial paternal involvement and others more commonly maternal care.

Conservation status varies among ratites. Many species face threats from habitat loss, hunting, and introduced predators. Some populations, such as certain ostriches and cassowaries, are listed as vulnerable or endangered, and protective measures and habitat management are pursued in many regions.