Common loons leave their breeding areas in late October and head for their wintering grounds along the Gulf of Mexico and the Atlantic coast. Until the early 1990s, little was known about the timing of the loonâs migration, their migratory routes, and where they spent the winter. Starting in 1991, biologists in northern Wisconsin have banded more than 3,600 adult loons and chicks, and have learned a great deal about their behavior. Get the scoop on their research on our podcast.