Become Independent
Noun
すだち
どうして鳥は飛べるようになる前に巣立ちをするのですか。
Why do birds leave the nest before they can fly?
When you stand up out of the nest, you're getting ready to leave it. Your mother may be sad about this, but this means it's time to leave the nest and become independent.
The readings are from the words 巣 and 立つ put together.