FIG. 1.

Locations of bird observatories that participated in the study. Abbreviations for the names of Canadian provinces and U.S. states, respectively, are as follows: MB, Manitoba; ON, Ontario; QC, Quebec; NB, New Brunswick; NS, Nova Scotia; and MN, Minnesota; WI, Wisconsin; MI, Michigan; OH, Ohio; PA, Pennsylvania; NY, New York; NE, New England states; and ME, Maine. Filled triangles indicate the locations of bird observatories participating in the study: 1, Thunder Cape; 2, Pelee Island; 3, Long Point (comprising the Old Cut, Breakwater, and Tip observatories); 4, Haldimand (comprising the Ruthven, Rock Point, and Selkirk observatories); 5, Tommy Thompson Park, Toronto; 6, Prince Edward Point; 7, McGill, Montreal; 8, Atlantic, Nova Scotia.