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
penguins. Most flightless
birds evolved in the absence of predators, on islands,
and lost the power of flight because they had few enemies. 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[1].
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 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[2].
Some flightless variety of island birds are closely
related to flying varities, impling flight is a signifcant
biological cost.
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
Moas.
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)[3].
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.
List of
recent flightless birds
Ratites
Grebes
- Junin Flightless Grebe
Titicaca Flightless Grebe
Pelican-like birds
- Flightless Cormorant
Spectacled Cormorant (extinct)
Petrel-like birds
Duck-like birds
- Moa-nalo (extinct)
Magellanic Flightless Steamer Duck
Falkland Flightless Steamer Duck
White-headed Flightless Steamer Duck
Auckland Island Teal
Rails and relatives
- 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
Gulls and relatives
Parrots
Doves and relatives
- Dodo (extinct)
Rodrigues Solitaire (extinct)
Songbirds
-
Stephens Island Wren (extinct)
See also
Reference
Taylor, Barry (1998).
Rails: A Guide to the Rails, Crakes, Gallinules and Coots of
the World. Yale University Press.
ISBN 0-300-07758-0.