1. Department of Natural Resource Management, Box 2140B, South Dakota State University, Brookings, SD 57007.
2. U.S. Geological Survey, South Dakota Cooperative Fish and Wildlife Research Unit, Department of Natural Resource Management, South Dakota State University, Brookings, SD
3. School for Environment and Sustainability and Program in the Environment, University of Michigan, Ann Arbor, MI
4. Department of Applied Ecology, North Carolina State University, Raleigh, NC
5. U. S. Geological Survey, Great Lakes Science Center, Ann Arbor, MI