Do swallows use old nests or always build new?

Question

Do swallows use old nests or always build new?

Answer 1

If they find old nests they are happy to re-use them. Otherwise build new ones.

Answer 2

They try to use old nests because then they can spend more time on feeding than building. But if they can't, then they would go ahead and build a new one.

Answer 3

Swallows are one of the few bird species that will re-use an old nest, during the same season, or even the following year if the nest lasts throughout the winter.