1. U.S. Geological Survey, Fort Collins Science Center, 2150 Centre Ave, Building C, Fort Collins, CO 80526, USA
2. Natural Resource Ecology Laboratory, Colorado State University, in Cooperation with the U.S. Geological Survey, Fort Collins Science Center, 2150 Centre Ave, Building C, Fort Collins, CO 80526, USA
3. Biology Department, College of William and Mary, 540 Landrum Dr, P.O. Box 8795, Williamsburg, VA 23187, USA