Seawatching is the challenging act of identifying waterbirds in flight. Since more than one hundred different species can fly past an observation point, often at great speed or in tightly packed, mixed-species flocks, identification of these distant shapes can be a mystery. The keys to the mystery—the subtle traits that unlock the identity of flying waterbirds, be it wingbeat cadence, individual structure, flock shape and behavior, or subtle flashes of color—are revealed in this guide.Though commonly called seawatching, this on-the-fly observation and identification method is by no means restricted to the coast. There are impressive waterbird migrations on the Great Lakes, the Gulf of Mexico, and many inland lakes and rivers. Nor is it restricted to migrating waterfowl, as the principles of flight identification apply as effectively to ducks flushed off a pond as to distant migrating flocks. Like Hawks in Flight and The Shorebird Guide, the Peterson Reference Guide to Seawatching breaks new ground, provides cutting-edge techniques, and pushes the envelope in bird identification even further.