Blackpoll Warbler
These warblers are tiny, active birds returning from wintering grounds in Puerto Rico, the Lesser Antilles, or northern South America. Their route averages 3,000 km (1,864 mi) over water, and could have meant a nonstop flight lasting up to 88 hours! Blackpoll Warblers are one species that does loop migration: It flies one route during fall migration, and a different route during the spring. Because of prevailing NW winds in the fall, Blackpolls take off from New England and fly over the Atlantic to northeastern South America. In the spring, those northwesterly winds no longer exist, and the Blackpolls cross the Gulf of Mexico or island-hop across the Caribbean and continue their migration over land.

Image: Laura Erickson