Black-throated Blue Warbler, photo by The Nature Conservancy

Saving Great Lakes Stopover Sites

Every spring and fall, tens of millions of migrating birds sweep through the Great Lakes region and stop at a variety of sites on their way to breeding grounds as far north as Greenland and the Arctic Ocean and wintering grounds as far south as Argentina’s Tierra del Fuego.  These stopover sites provide birds with critical food and shelter during migration.  Loss of stopover habitats poses an ongoing threat to the health and stability of migratory bird populations in the Great Lakes region.

Kohler Andrae State Park, photo by Sumner Matteson

For decades, reported declines in migratory bird populations have resulted in studies focused primarily on breeding and, to a lesser extent, wintering bird populations.  Little serious attention has been given to identifying, prioritizing and protecting migratory bird stopover sites.

Many ornithologists believe that migration may be a part of the life cycle in which birds are most vulnerable.  During migration, birds are under physiological stress and mortality may be quite high.  For one group of migrants, the wood warblers, mortality rates during migration may be 15 times higher than in breeding and wintering periods, with adult rates as high as 85 percent for migrating Black-throated Blue Warblers.  Similar rates might also be true for the Wood Thrush and other forest-dependent migratory songbirds.