List a few flight adaptations in birds.

Flight adaptations of the birds are the following:
(1) Forelimbs are modified into wings.
(2) Body is covered with exoskeleton of water-proof and light-weight feathers.
(3) Long bones of endoskeleton are pneumatic having air cavities.
(4) A11 birds are toothless; their jaws are modified into horny beaks.
(5) Body is streamlined to reduce air resistance during its flight.
(6) Birds have air sacs helping in double respiration.
(7) Flights muscles are well developed.
(8) Tail feathers form a steering apparatus.
(9) Birds have a acute vision.