For small songbirds, surviving a cold winter night can be challenging. Their bodies lose heat faster than those of larger birds. So little birds have found resourceful ways to stay warm — like huddling close together with other birds. But the Verdin, a tiny bird of the Southwest, does something few other birds do to keep warm: it builds extra nests to roost in, in the winter.More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.