Acknowledgments

We thank K. Martin for help with literature review for the revised manuscript. H. G. Lumsden, M. L. Mallory and D. K. McNicol of the Canadian Wildlife Service Ontario Region, A. J. Erskine, A. Wyss and D. Eggeman of the Florida Game and Fresh Water Fish Commission and P. Blums, University of Missouri Gaylord Lab, for allowing us to cite unpublished data. Band recovery and harvest data were provided by J. R. Kelley and G. Smiley, Office of Migratory Bird Management. We thank Dr. Robert Chandler for contributing the fossil history section. Data from natural cavities were provided by the North American Nest Record Card Program, Maritimes Nest Record Scheme, Ontario Nest Records Scheme, Quebec Nest Record Card Program, and Western Foundation of Vertebrate Zoology. We thank all the volunteers who collected this information. For comments and observations we thank B. Davis, A. J. Erskine, M. Gosselin, J. Hansen, C. Harris, J. Herbert, and T. Retterer. For responding to a questionnaire about Hooded Merganser abundance and distribution, we thank personnel from 120 National Wildlife Refuges, state management areas, and private companies. Field studies by LHF and KMD were funded by Gaylord Memorial Laboratory, U.S. Fish and Wildlife Service, Office of Migratory Bird Management (contract no. 14–16–0009–78–974), Missouri Department of Conservation, University of Missouri Agriculture Experiment Station, and Missouri Cooperative Wildlife Research Unit. Support for B. Dugger and K. Dugger during manuscript revisions was provided by Department of Fisheries and Wildlife, Oregon State University. Comments by M. L. Mallory, M. C. Zicus, and A. Poole greatly improved this manuscript.