What are the modifications that are observed in bird that help in flying?

(a) Birds have feathers which help them to fly.
(b)Forelimbs are modified into wings for flight.
©The avian flight muscles are used for flying.
(d)The long bones are hollow and connected to air cavities to reduce weight.
(e)The bones are light.
(f)Feathers decrease water loss from body.
(g)High metabolic rate to lift body from ground.