Yes birds sometimes use summertime nests in the winter!
I was really surprised this morning when I came downstairs. I saw a little chickadee near the window with a twig in its mouth. Then it flew down into one of our boxes. I wondered why? Its cold outside... courtship, nesting and breeding is over for the year, right?
Well I did some research and it turns out that many the birds in your yard re-use the summer nests in winter, as spending the night in a semi-enclosed space keeps them up to 15 degrees warmer, enabling them to survive much easier. Spending 50% less energy heating their body at night allows them to survive easier when food is scarce, avoiding starving to death. Birds also sometimes store food in their nests also. Also birds often shelter together to keep warm - an amazing 61 wrens have been found roosting in one nestbox to shelter from the cold.
So keep an eye out for birds nesting in your yard but please dont disturb them too much. Put out lint where you can. And make sure they have lots of available food! :)
