Being able to fly does not make a bird a bird. Bats and many insects also possess this adaptation. Birds are also not birds because they lay eggs. Most fish, invertebrates, amphibians and reptiles and even a couple of animals lay eggs. What makes a bird a bird is their feathers. And while most birds use their feathers to fly, some species today primarily use them to show off to mates, insulate their body from extreme temperatures and to camouflage.
Basically, some birds cannot fly.
As BirdLife writes in their article “Flightless Birds”
“Aves evolved from Dinosauria by specializing in flying capability, but the flightless birds are those which abandoned that capability. Alternatively, they developed swimming or running capabilities; for example, penguins swim free in the water just like fish, and most ratites including Ostriches and Rheas run very fast with their strong legs instead of flying. Besides, some birds living in the places such as outer islands where there is no enemy preying on them, even if they are closely related to flying species, tend to become flightless in case their feeding and breeding are possible.?lt;/span>
Why Do Birds Fly & Others Don’t
Ostriches, a famous example, are the largest and heaviest of the extant birds that cannot fly. “Ostrich are in a family of flightless birds referred to as Ratites,?said Joel Brust, President of the American Ostrich Association (AOA). “In this family are the ostrich, emu, rhea, kiwi and cassowary,?all of which are flightless.
“The ratite family seems to have survived a long time during the evolution of the earth and its species,?Brust noted.
These birds are quite unique in other ways too. As National Geographic, in their article “Why Fly? Flightless Bird Mystery Solved, Say Evolutionary Scientists?writes:
“Ostriches, emus, cassowaries, rheas, and kiwis can’t fly. Unlike most birds, their flat breastbones lack the keel that anchors the strong pectoral muscles required for flight. Their puny wings can’t possibly lift their heavy bodies off the ground. These flightless birds, called ratites, are clearly different from other avian species.
Darwin noticed, and he predicted that ratites were related to each other. His contemporary, Thomas Huxley, found another commonality among them: The arrangement of bones in the roofs of their mouths appeared more reptile-like than that of other birds.?lt;/span>
Since they don’t need to stay lightweight to fly, birds like ostriches can grow larger. Ratites, however, are not the only flightless birds. Dr. Mike Dickison, Curator of Natural History at Whanganui Regional Museum in New Zealand told me that there are about 50 different types of flightless birds today.
“But several times that number went extinct within the last thousand years or so, thanks to humans,?he soberly added.
“Some of them, like the different species of kiwi or cassowary, are related,?he said, “but most flightless birds have a close relative that flies, showing that each species became flightless independently.”
Flight is difficult and expensive, even for humans, Dickison said. “For a bird to be able to fly it has to devote its body and lifestyle to staying small, light, and gathering enough energy to get off the ground. If it isn? absolutely necessary to fly, birds will quickly evolve flightlessness.”
He says that bird species have gone flightless dozens of times. Being flightless allows birds to become larger and get by with lower-quality food like grass and leaves ?just think about those large ratites, ostriches, emus and rheas.
“We?e now sure that all flightless birds are descended from flying ancestors, and the very first birds all flew,” Dickison said. According to the fossil record, scientists can tell birds have been going flightless about as long as there have been birds. Penguins lost flight a very long time ago, and scientists used to think the same was true for ratites, but new DNA evidence suggests that the common ancestor of ratites could fly, and remarkably each kind of ratite became flightless independently.
“Some kinds of birds, like rails, become flightless at the drop of a hat,?Dickison said. “There could have been 1000 species of flightless rails in the Pacific, one for every island, and almost every last species is now extinct. Other birds, perhaps because of the way they develop as chicks, are much less likely to lose flight. Although songbirds are by far the largest bird group, almost none of them have become flightless: an extinct bunting in the Canary Island, and a few New Zealand wrens.?lt;/span>
There’s even one flightless parrot: the kakapo.
In the February 1999 issue of The Condor,an international journal of avian biology published by the Cooper Ornithological Society, scientists discovered the extinct bunting in the Canary Island named the long-legged bunting. On the floor of a volcanic cave were bones of different species of birds, mammals and one lizard.
Flickr: kakapo_541643s by jidanchaomian is licensed under CC by 2.0. The kakapo is the only flightless parrot in the world, and also the heaviest.
Extinct Flightless Birds
The author of the paper does admit that, “Evaluating flight capability of a fossil bird is not easy because osteological data may not indicate clearly whether the animal was a weak flyer or flightless. By comparing the extinct flightless wrens of New Zealand and species of the same genus to the long-legged bunting of the Canary Island it was found that this species was most likely flightless to the reduction of wing length.
Flightless species has been noted in extinct birds including waterfowl, parrots, pigeons, gulls, grebes, penguins, kingfishers and pelicans. One specimen really surprised me: the Cuban giant owl or giant cursorial owl (Ornimegalonyx). I would imagine it would be quite difficult for a raptor to be flightless.
Nearly three complete skeletons have been found dating back to the late Pleistocene period, which is about 10,000 years ago. The Cuban giant owl, measured 3.5 feet in height, weighed more than 20 pounds and is believed to be the largest owl that ever existed. It is believed that they preyed on large rodents the size of nutria or capybara and ground sloths, using a pouncing technique.
Species Of Flightless Bird
Here is a sampling of flightless bird types:
- Ratites: This order includes birds like the ostriches, emus, cassowaries, moa, kiwis and rheas.
- Waterfowls: Flightless waterfowl birds include the Auckland teal and steamer ducks.
- Penguins: According to FactZoo.com:
“Living primarily in the southern hemisphere, penguins are a group of aquatic, flightless birds that have become highly adapted to life in the water. They are the largest order of entirely flightless birds ?Sphenisciformes. There are between 17 and 20 different species of penguin, all featuring counter shaded dark and white plumage (they always seem to be dressed in regal attire), and all having wings that have evolved into flippers. The wings are unlike any other bird as they have become dense, solid and muscular for swimming instead of hollow and light for flight. Their webbed feet are set far back and make them balance with their tails and waddle awkwardly.”
- Parrots: The only flightless bird is the kakapo.
- Grebes: Flightless grebes include Junin grebe and the titicaca grebe.
- Gruiformes: Flightless birds in this order include rail birds (such as Calayan rail and the snoring rail), the weka, and the Gough island moorhen.
Another flightless bird is the flightless cormorant.
Famous extinct flight birds include the dodos and the moas.