1. Center for Wildlife Ecology, Illinois Natural History Survey, 607 East Peabody Drive, Champaign, Illinois 61820, USA
2. Division of Wildlife Resources, Illinois Department of Natural Resources, 607 East Peabody Drive, Champaign, Illinois 61820, USA
3. College of Veterinary Medicine, University of Illinois, 2001 South Lincoln, Urbana, Illinois 61801, USA
4. Forbes Biological Station, Center for Wildlife Ecology, Illinois Natural History Survey, P.O. Box 590, Havana, Illinois 62644, USA
5. Illinois State Water Survey, 2204 Griffith, Champaign, Illinois 61820, USA