1. Department of Watershed Sciences; Utah State University; Logan UT 84322 USA
2. Department of Biology; Colorado State University; Fort Collins CO 80523 USA
3. Fort Collins Science Center; U.S. Geological Survey; 2150 Centre Ave., Bldg C Fort Collins CO 80526 USA
4. Science and Resource Management Division, National Park Service; Glen Canyon National Recreation Area; P.O. Box 1507 Page AZ 86040 USA