Flightless bird

Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim, and are thought to have evolved from their flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguins. It is believed by some that most flightless birds evolved in the absence of predators, on islands, and lost the power of flight because they had few enemies — although this is likely not the case for the ratites; the ostrich, emu and cassowary, as all have claws on their 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 kiwis, several species of penguins, and the takahe) than any other country. One reason is that until the arrival of humans roughly a thousand years ago, there were no large land predators in New Zealand; the main predators of flightless birds were larger birds.

Some flightless varieties of island birds are closely related to flying varieties, implying flight is a significant biological cost.

The smallest flightless bird is the Inaccessible Island Rail (length 12.5 cm, weight 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) (although some extinct species grew to larger sizes).

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

There were also other families of flightless birds, such as the now extinct Phorusrhacidae, that evolved to be very powerful terrestrial predators.

List of recent flightless birds

The following are flightless birds during or after the Holocene period.

Ratites

• Ostrich
• Emu
• Kangaroo Island Emu (extinct)
• King Island Emu (extinct)
• Cassowaries
• Moa (extinct)
• Elephant birds (extinct)
• Kiwis
• Rheas

Podicipediformes (Grebes)

• Junin Flightless Grebe
• Titicaca Flightless Grebe
• Atitlán Grebe (extinct, reportedly flightless [Hunter 1988])

Pelicaniformes (Pelicans, Cormorants, et al)

• Flightless Cormorant

Sphenisciformes (Penguins)

• Penguins

Coraciiformes (Kingfishers, Hornbills, et al)

• Giant Hoopoe (extinct)

Anseriformes (Waterfowl)

• Moa-nalos (extinct)
• Magellanic Flightless Steamer Duck
• Falkland Flightless Steamer Duck
• White-headed Flightless Steamer Duck
• Auckland Island Teal
• Campbell Island Teal

Ciconiiformes (Herons, Ibis)

• Réunion Sacred Ibis (extinct)

Gruiformes (Cranes, Rails)

• Cuban Flightless Crane (extinct)
• Red Rail (extinct)
• Rodrigues Rail (extinct)
• Woodford's Rail (probably flightless)
• Bar-winged Rail (extinct, probably flightless)
• Weka
• New Caledonian Rail
• Lord Howe Woodhen
• Calayan Rail
• New Britain Rail
• Guam Rail
• Roviana Rail ("flightless, or nearly so" [Taylor 1998])
• Tahiti Rail (extinct)
• Dieffenbach's Rail (extinct)
• Chatham Rail (extinct)
• Wake Island Rail (extinct)
• Snoring Rail
• Inaccessible Island Rail
• Laysan Rail (extinct)
• Hawaiian Rail (extinct)
• Kosrae Island Crake (extinct)
• Henderson Island Crake
• Invisible Rail
• New Guinea Flightless Rail
• Lord Howe Swamphen (extinct, probably flightless)
• North Island Takahe (extinct)
• Takahe
• Samoan Wood Rail
• Makira Wood Rail
• Tristan Moorhen (extinct)
• Gough Island Moorhen
• Adzebills (extinct)
• Kagu
• Tasmanian Native-hen

Charadriiformes (Gulls, Terns, Auks)

• Great Auk (extinct)
• Diving Puffin (extinct)

Psitticiformes (Parrots)

• Kakapo
• Broad-billed Parrot (extinct)

Columbiformes (Pigeons, Doves)

• Dodo (extinct)
• Rodrigues Solitaire (extinct)
• Viti Levu Giant Pigeon (extinct)

Caprimulgiformes (Nightjars)

• New Zealand Owlet-nightjar (extinct)

Passeriformes (Perching Birds)

• Stephens Island Wren (extinct)

See also

• Ratite
• Extinct birds
• Gastornis
• Phorusrhacidae
• Dinosaurs
• Feathered dinosaurs
• Origin of birds: Secondary flightlessness in dinosaurs

References

• Hunter, Laurie A (1988). "Status of the Endemic Atitlan Grebe of Guatemala: Is it Extinct?". Condor 90 pp. 906–912. Retrieved on 2007-04-03.
• Taylor, Barry (1998). Rails: A Guide to the Rails, Crakes, Gallinules and Coots of the World. Yale University Press.

External links

• TerraNature pages on New Zealand flightless birds
• Kiwi in Te Ara - the Encyclopedia of New Zealand