Warming temperatures and southerly winds, preferably southwest winds, can produce flights of hundreds of thousands of raptors at Braddock Bay in a single day, making its shore one of the finest places in North America to observe the spring hawk migration. Fifteen species of daytime migrating raptors regularly occur here between late February and mid June, and rare species such as the Black Vulture and Swainson's Hawk may also be seen. The peak of the migration period is late April, when large groups of Broad-winged Hawks traverse the region. As spring migrating hawks move north toward the Great Lakes from the Appalachian region and farther south, their flight lines converge and narrow. Raptors travel great distances using very little energy by soaring in bubbles of warm air rising from the land, called thermals. Because these thermals are stronger over land than water, and because most hawks do not like to cross large bodies of water, they become funneled and concentrated into a very narrow corridor along the shore, following the Seaway Trail.
