What Is a Ratite?

Definition:

(noun) Any of the large, flightless birds that lack a keel on the sternum. The keel is a broad extension of the sternum where breast muscles attach and is essential to give birds the skeletal and muscular stability for flight. Without the keel, a bird cannot fly, no matter how well developed its wings may be. Because the larger flightless birds do not have this bone, their wings are often stunted or simplified, though they may still be used for courtship displays, aggressive posturing or other purposes.

Ornithologists have historically believed that all ratites were intimately related and had evolved similarly, but modern study techniques, including DNA and genetic analysis, indicate that these birds evolved flightlessness in much more diverse ways than previously considered. Today, there are multiple bird families that include flightless species, such as the Apterygidae, Casuariidae, Dromaiidae and Struthionidae families, among others, though they are all considered ratites.

In addition to the lack of a keel, ratites share other characteristics, including:

Generally underdeveloped breast muscles, as they are not necessary for flight
Stunted wings that are often out of proportion with the birds' overall size
Strong, powerful legs for walking and running, as well as defense if needed
Less organized plumage that may appear fluffy or furry, because it does not need to be streamlined for efficient flight

While the geographic distribution of ratite species varies, they are most often found in more open habitats or open forests where they can maneuver easily.

Ratites are found in South America, Africa, Australia, New Zealand and Indonesia, though domesticated and hybrid birds are often livestock on commercial farms in different parts of the world. These birds are often residents of zoos and aviaries as well.

Many ratite species are extinct, but the most familiar of the living ratites include the common ostrich, great spotted kiwi, emu, American rhea and southern cassowary.