1. Merriam-Powell Center for Environmental Research and Department of Biological Sciences; Northern Arizona University, 805 S. Beaver Street; Flagstaff AZ 86011-6077 U.S.A.
2. Southwest Biological Science Center; U.S. Geological Survey, 2255 N. Gemini Drive; Flagstaff AZ 86001 U.S.A.
3. Forest and Rangeland Ecosystem Science Center; U.S. Geological Survey, 970 Lusk Street; Boise ID 83706 U.S.A.