From Longman Dictionary of Contemporary Englishleave/fly the nestleave/fly the nestto leave your parents’ home and start living somewhere else when you are an adult Both daughters were ready to fly the nest. → nest
Examples from the Corpus
leave/fly the nest• It is so rarely when all the fledglings have left the nest, to have them all together again.• When the host leaves the nest, the cuckoo makes its approach in a long, silent hawk-like glide.• Barn owls leave the nest at two to three months and are sexually mature at one year.• She usually builds on the shores of an estuary and there she sits devotedly, seldom leaving the nest.• Once deposited, she leaves the nest and he immediately fertilizes the eggs.• Unfortunately for her, the host bird showed no inclination to leave the nest.• After about three weeks, the young cuckoo is ready to leave the nest.• If, however, the host appears reluctant to leave the nest, the cuckoo has a more direct approach. 