Solution:

The following are some of the differences identified in birds that aid in flight:

(i) Feathers are present.

(ii) To aid flight, forelimbs are transformed into wings.

(iii) Scales on the hind limbs.

(iv) They have hollow or pneumatic bones, which lighten the skeleton.

(v) The absence of a urinary bladder enables them to lose weight and makes it easier for them to fly.

(vi) Their streamlined bodies produce less resistance and allow them to fly for longer periods of time.