Question

why do birds leave their old nests?

Answer 1

First of all, remember that birds build nests specifically for hatching eggs and raising young. Usually, as soon as the young are ready to leave, the nest is abandoned. It's actually quite dangerous to stay in a nest--always returning to the same place means the bird family is vulnerable to discovery by predators, plus, even though most birds keep their nests clean, a nest can harbor germs and parasites. This means building a nest can mean striking a delicate balance between creating a safe place to raise young and becoming vulnerable to all sorts of dangers.