1. Migratory Bird Center; Smithsonian Conservation Biology Institute; National Zoological Park Washington District of Columbia 20013 USA
2. United States Geological Survey; Patuxent Wildlife Research Center; Laurel Maryland 20708 USA
3. Florida Fish and Wildlife Conservation Commission; Fish and Wildlife Research Institute; St. Petersburg Florida 33701 USA
4. Department of Environmental Studies; University of North Carolina Wilmington; Wilmington North Carolina 28403 USA