Fledge

Fledge is the stage in a young bird's life when the feathers and wing muscles become developed enough for flight. It also describes the act of a chick's parents raising it until it is fully grown. A young bird that has recently fledged but still needs care and feeding is called a fledgling.
In ornithology, fledging has many meanings, depending on species. Birds are sometimes considered fledged once they leave the nest, even if they still cannot fly.