1. United States Geological Survey; Northern Prairie Wildlife Research Center; 8711 37th Street SE Jamestown ND 58401 USA
2. United States Geological Survey; Northern Prairie Wildlife Research Center; 204 Hodson Hall 1980 Folwell Avenue Saint Paul MN 55108 USA
3. United States Fish and Wildlife Service; Division of Migratory Bird Management; Population and Habitat Assessment; 11510 American Holly Drive Laurel MD 20708 USA
4. School of Renewable Natural Resources; Louisiana State University Agricultural Center; Baton Rouge LA 70803 USA