Flightless birds

Flightless birds are birds which cannot fly. They rely on their ability to run or swim, and have evolved from their flying ancestors.^[1] There are about 60 species living today,^[2] the best known being the ostrich, emu, cassowary, rhea, kiwi, penguin, takahe birds have smaller wing bones and a greatly reduced or absent keel on their breastbone. The keel anchors muscles needed for wing movement.^[2] Flightless birds also have more feathers than flying birds.

New Zealand has more species of flightless birds (such as the kiwis, several species of penguins, and the takahe) than any other country. One reason is that until the arrival of humans a thousand years ago, there were no large land predators in New Zealand. The main predators of flightless birds were large eagles.^[3]

Some flightless varieties of island birds are closely related to flying varieties. This suggests that the apparatus of flight has a significant biological cost. As soon as birds do not need to fly, there is selection against flight.

The smallest flightless bird is the Inaccessible Island Rail (length 12.5 cm, weight 34.7 g). The largest (both heaviest and tallest) living flightless bird, is the ostrich (2.7 m, 156 kg), although some extinct birds grew to larger sizes.

Flightless birds are easy 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.

1. ↑ "New Zealand Ecology - Moa". TerraNature. Retrieved 2007-08-27.
2. ↑ ^{2.0 2.1} "The bird site: flightless birds". Archived from the original on 2007-07-13. Retrieved 2007-08-27.
3. ↑ "New Zealand's Icon:Flightless". Archived from the original on 2007-08-18. Retrieved 2007-08-27.