"How do birds stay warm in the winter?" One of our patrons stocks several birdfeeders year-round. With the cold weather we've been having lately, she was worried about how her birds were keeping warm. Putting "how do birds stay warm" into an online search engine showed that this is a popular concern.
Some birds will fly south for the winter, especially the species that eat insects rather than seeds. However, the ones that stick around in snowy climes have their own ways to stay cozy. Birds' natural oils help waterproof their feathers, and some birds will grow extra feathers for the winter. Like people, they can shiver to stay warm, and they're also known to sit in the sun when they can, sometimes spreading their wings to get as much sun as possible. When sunshine isn't an option, they fluff up their feathers to trap pockets of air, which then serve as excellent insulation. On especially cold nights, some will enter a torpor, dramatically lowering their body temperature and heartbeat so as to conserve warmth. They may also huddle together and share heat that way.
To keep their legs warm, birds can either stand on one leg, tucking the other up under their feathers, or hunker down to keep both legs cozy. According to an article at birding.about.com, the special scales on birds' legs also can help retain heat.
Bird lovers have several ways to help their feathered friends make it through the winter. Providing good winter food such as suet and black oil sunflower seeds will give birds the calories they need to stay warm. Keeping a heated birdbath will give them a reliable source of drinking water. Finally, having a clean birdhouse, roost box, or just a yard full of evergreen trees and shrubs can give birds a snug place to roost. Sally Roth's "Attracting Birds to Your Backyard" suggests putting your old Christmas tree outside where it can serve as a shelter.
For information on building birdhouses and birdfeeders, patrons can check out some of the books we have here at the library, including Paul Meisel's "Bird-Friendly Nest Boxes & Feeders" and Don McNeil's "The Birdhouse Book." For information on attracting and feeding birds, we have "North American Birdfeeder Guide" by Robert Burton and Stephen W. Kress, and "Attracting Birds to Your Backyard" by Sally Roth.