1. Cooperative Wildlife Research Laboratory; Department of Zoology; Southern Illinois University Carbondale; Carbondale IL 62901-6504 USA
2. Cooperative Wildlife Research Laboratory; Department of Forestry; Southern Illinois University Carbondale; Carbondale IL 62901-6504 USA
3. Forest Wildlife Populations and Research Group; Minnesota Department of Natural Resources; Grand Rapids MN 55744 USA
4. Department of Zoology; Southern Illinois University Carbondale; Carbondale IL 62901-6501 USA