What does his mother do to force him to fly?

Push him out of the nest

Explanation:

If you're talking about birds, that's what they do to make their children fly

parents want there kids to grow and sometimes that means pushing them to break past there limits and leave there comfort zone also when you fly you no longer rely on your parents your parents know they wont be there forever and want to make sure you can take care of your self when they are gone.

the answer your probrably looking for

i dont know if this comes from a book or a poem but it connects to a family of gulls trying to convice the baby to fly the mother takes a peice of fish and tries to make the baby come to her by flying higher and higher the parents also scold the kid and threaten to starve him if he doesnt fly they called him a coward for not having the courage to take the first flight.