Flightless birds evolved from flying ancestors; there are about forty species in existence today. The best known flightless birds are the ostrich, emu, cassowary, rhea and penguin. Flightless birds lost the power of flight because they had few enemies. Most flightless birds evolved in the absence of predators, on islands. A notable exception, the ostrich, which lives in the African savannas, has claws on its feet to use as a weapon against predators.

Two key differences between flying and flightless birds are the smaller wing bones of flightless birds and the absent (or greatly reduced) keel on their breastbone. The keel anchors muscles needed for wing movement^*. Flightless birds also have more feathers than flying birds.

New Zealand has more species of flightless birds (including the kiwi, penguin, and takahe) than any other country. One reason is that until the arrival of humans roughly 1000 years ago, there were no land mammals in New Zealand other than three species of bat; the main predators of flightless birds were larger birds^*.

With the introduction of mammals (among them humans) to the habitats of flightless birds, many have become extinct, including the Great Auk, the Dodo, and the Moa.

The smallest flightless bird is the Inaccessible Island Rail (12.5 cm, 34.7 g). The largest (both heaviest and tallest) flightless bird, which is also, the largest living bird is the ostrich (2.7 m, 156 kg)^*.

Flightless birds are the easiest to take care of in captitivity because they do not have to be kept in cages. Ostriches were once farmed for their decorative feathers. Today they are raised for their skins which are used to make leather.

List of flightless birds

Ratites

• Ostrich
• Emu
• Cassowary
• Moa (extinct)
• Kiwi
• Rhea
• Tinamou

Pelican-like birds

• Flightless Cormorant
• Spectacled Cormorant (extinct)

Petrel-like birds

• Penguins

Duck-like birds

• Moa-nalo (extinct)
• Auckland Island Teal

Rails and relatives

• Takahe
• Weka
• Adzebill (extinct)
• Wake Island Rail (extinct)
• Inaccessible Island Rail
• Lord Howe Woodhen
• Kagu
• Laysan Rail (extinct)
• Hawaiian Rail (extinct)

Gulls and relatives

• Great Auk (extinct)

Parrots

• Kakapo

Doves and relatives

• Dodo (extinct)
• Rodrigues Solitarie (extinct)

Songbirds

• Stephens Island Wren (extinct)

See also

• Extinct birds
• Ratite

Flightless birds

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