n an ice-crusted soybean field on Maryland’s Eastern Shore, under a brilliant
blue sky, hundreds of large white birds are singing in a strange chorus. They
are tundra swans, the largest birds native to the Chesapeake Bay region, with
five-foot wing spans, dazzling white feathers, and black beaks. They nest and
raise their young in the frozen wastelands of Alaska and northern Canada. Then,
every winter, they fly as much as 3,000 miles south—spending almost three
months in the air.