Answer & Explanation:::::::
One of the requirements for heavier-than-air flying machines is a structure that combines strength with light weight. This is true for birds as well as planes. Birds have many physical features, besides wings, that work together to enable them to fly. They need lightweight, streamlined, rigid structures for flight. The four forces of flight – weight, lift, drag and thrust – affect the flight of birds.
Flying birds have:
lightweight, smooth feathers – this reduces the forces of weight and drag
a beak, instead of heavy, bony jaws and teeth – this reduces the force of weight
an enlarged breastbone called a sternum for flight muscle attachment – this helps with the force of thrust
light bones – a bird’s bones are basically hollow with air sacs and thin, tiny cross pieces to make bones stronger – this reduces the force of weight
a rigid skeleton to provide firm attachments for powerful flight muscles – this helps with the force of thrust
a streamlined body – this helps reduce the force of drag
wings – these enable the force of lift.
Wings
The shape of a bird’s wing is important for producing lift. The increased speed over a curved, larger wing area creates a longer path of air. This means the air is moving more quickly over the top surface of the wing, reducing air pressure on the top of the wing and creating lift. Also, the angle of the wing (tilted) deflects air downwards, causing a reaction force in the opposite direction and creating lift.
Hope this helped..