1. Department of Wildland Resources and Ecology Center; Utah State University; Logan UT 84322-5230 USA
2. School of Geographical Sciences and Urban Planning; Arizona State University; Tempe AZ 85287-5302 USA
3. U.S. Geological Survey; Utah Cooperative Fish and Wildlife Research Unit, and Department of Wildland Resources; Utah State University; Logan UT 84322-5230 USA