Roger F. Pasquier, a lifelong birder, has had a career with the International Council for Bird Conservation, the Environmental Defense Fund, and the National Audubon Society, and is currently an associate in the Department of Ornithology at the American Museum of Natural History. His many books include Watching Birds and Masterpieces of Bird Art. How birds have evolved and adapted to survive winter Birds in Winter is the first book devoted to the...

During a cold spell in December, a song sparrow that has not migrated south must adapt to the changes that winter brings.