1. Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, USA
2. Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA
3. Department of Biological Sciences, Colorado Mesa University, Grand Junction, Colorado, USA
4. Department of Biology, Warren Wilson College, Asheville, North Carolina, USA
5. Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
6. Department of Biological Sciences, San José State University, San Jose, California, USA
7. U.S. Fish and Wildlife Service, National Wildlife Refuge System, Natural Resource Program Center, Fort Collins, Colorado, USA