1. U.S. Geological Survey; Iowa Cooperative Fish and Wildlife Research Unit, 338 Science Hall II, Iowa State University; Ames IA 50011 USA
2. Department of Natural Resource Ecology and Management; Iowa State University; Ames IA 50011 USA
3. Iowa Department of Natural Resources; 1203 North Shore Drive Clear Lake IA 50428 USA
4. Department of Ecology; Evolution and Organismal Biology, 253 Bessey Hall, Iowa State University; Ames IA 50011 USA
5. Iowa Cooperative Fish and Wildlife Research Unit and Department of Natural Resource Ecology and Management; 339 Science Hall II, Iowa State University; Ames IA 50011 USA
6. U.S. Geological Survey, Iowa Cooperative Fish and Wildlife Research Unit; 342 Science Hall II, Iowa State University; Ames IA 50011 USA