Aerial adaptations or adaptations in birds due to which they can fly. Birds show many such adaptations which are as follows: Birds have Pneumatic bones which means hollow bones. These bones help to reduce weight of the body so that birds can fly easily. The hollow bones are filled with air which provides structural rigidity to the body. As an aerial adaptation aves have only left ovary and oviduct so that bodyweight is reduced. Sternum or breast bone has a keel which is a median ridge which brings about attachment with flight muscles to help in flying.