Question

List a few flight adaptations in birds.

Answer 1

All birds share some common characteristics. They are warm-blooded, endothermic animals. They are vertebrates due to the presence of backbones. All birds have a four-chambered heart and lay hard-shelled eggs as they possess certain characteristics of mammals.

Complete answer:
Most of the bodies of birds are well adapted for flying as its body is enclosed with an exoskeleton of feathers. The forelimbs of birds are modified into feathered wings and they have only two legs.
Their bodies are stream-lined to reduce air resistance. The feathers and wings of birds help them to fly.
Most of the bird's bones are hollowed out which makes their bodies very light in weight than human bones. Along with the feathers on their wings and tail, the long flight birds have an enlarged chest bone with well-developed flight muscles that helps them to balance and steer. Presence of air sacs in their body helps in double respiration in order to extract more amount of oxygen from each breath than other animals can. Birds require a greater amount of energy and power during their flight and so their four-chambered heart also helps them to get plenty of oxygen. The eyes of birds are much larger in size in relation to their body size but they have keener eyesight than humans. They also have acute vision and well-developed brains in which it takes only a few seconds to find a place to land safely and avoid crashing.

Note: Some birds like penguins and ostriches don't fly. But they still have feathers and wings. Most probably, the feathers in birds are evolved from the scales of reptiles. In fact, Scales can be seen even in bird's feet and legs.