What are the changes in birds bodies that adapts them to aerial habitat?

Explanation

i.Birds have hollow bones to make their body lighter for adaptation to aerial habitat. ii.Their body is spindle-shaped, to reduce air resistance during flight.
iii. Forelimbs are modified into wings. Digits are provided with claws and are covered with scales.
(iv) Exoskeleton is in the form of feathers. For e.g. Peacock, parrot, pigeon, duck, penguin, etc.