Affiliation: | 1. Wildlife Biologist, U.S. Fish and Wildlife Service, Chase Lake National Wildlife Refuge, Woodworth, ND 58496, USA;2. Wildlife Biologist, U.S. Fish and Wildlife Service, Morris Wetland Management District, Morris, MN 56267, USA;3. Wildlife Biologist, U.S. Fish and Wildlife Service, J. Clark Salyer National Wildlife Refuge, Upham, ND 58789, USA |