This bird is headed out of the cool conifer-dominated boreal forests of Canada, to a very different wintering habitat. "Maggies" overwinter throughout much of Central America, and in the Caribbean, and are far more general in their habitat preferences down there than on the breeding grounds. Crossing the open waters of Lake Erie is nothing for a bird that is headed 1,500 miles or more to get to where it's going. There'll be much more arduous water crossings than this along the way, but you can't blame the guy for stowing away and getting a free ride!
Here's an interesting fact about this bird's name. The first specimen was collected way back in 1810 by the "Father of American Ornithology", Alexander Wilson. This collection became the type specimen, which is the collection upon which the organism was originally described. Well, Al shot his warbler from the boughs of a magnolia tree, in which the migrant warbler just happened to be foraging in en route to its boreal breeding haunts. Thus, he named it after a southern tree which probably plays no important role in the biology of this bird.
Thanks to Mike for sharing these great photos, and the story.