1. Center for Ecosystem Science and Society Northern Arizona University FlagstaffArizona 86011‐5620 USA
2. Merriam‐Powell Center for Environmental Research Northern Arizona University Flagstaff Arizona 86011‐6077 USA
3. Department of Biological Sciences Northern Arizona University Flagstaff Arizona 86011‐6077 USA
4. Department of Biology Duke University Durham North Carolina 27708 USA