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to flap (wings)
to spread one's wings; to go out into the world
鳥が枝の上で羽ばたいた。
The bird flapped its wings on the branch.
トンビが空高く羽ばたいている。
A black kite is flapping its wings high in the sky.
ひなが初めて羽ばたく瞬間を写真に収めた。
I captured the moment a chick flapped its wings for the first time.