they justdo ... ok
The bird that can fly in the sky but can't walk on the ground is the swift. Swifts have very short legs and are adapted for life in the air, so they are not able to walk or stand on the ground like other birds.
They are flightless birds who have adapted their bodies/feathers/wings/feet/eyes for life in a marine environment. They are birds that "fly" through the water.
Penguins are birds
They have adapted to different ways of life. Chimps are adapted to living in tress & are herbivores, but humans are adapted to walking on the ground and are omnivores.
Survival, Food, Competition with ground animals, have their nests higher up, and to spot that booty from afar. That booty is righteous.
Some common birds that live in grassland regions include meadowlarks, pipits, ground-nesting birds like plovers, and birds of prey such as hawks and owls. These birds are adapted to the open grassy habitats and often feed on insects, seeds, or small mammals found in the grasslands.
swimming
burrowing animals and ground-dwelling birds
It will stick in the feathers
They have lighter bones than humans that allow them to be lifted off of the ground.
There is no such thing as a dinosaur that flys. The difference between a pteradoctyl and a bird is: Birds have feathers and pteradoctyl's don't. The difference between a oviraptor and a bird is: Oviraptor have hands and birds have wings.
Dodos are extinct, flightless ground dwelling birds (of the pigeon family) that lived on the island of Mauritius. As they are extinct they no longer have a life cycle, but when they were alive they had a life cycle similar to that of a chicken - eggs, chicks, mature birds.