1U.S. Geological Survey, Patuxent Wildlife Research Center, National Museum of Natural History, MRC-111, P.O. Box 37012, Washington, D.C. 20013, USA; 2Museum of Vertebrate Zoology, University of California, 3101 Valley Life Sciences Building, Berkeley, California 94720, USA; 3Rural Route 2, Box 52R, Bishop, California 93514, USA; 4Florida Museum of Natural History, P.O. Box 117800, University of Florida, Gainesville, Florida 32611, USA; 5Cornell Laboratory of Ornithology, 159 Sapsucker Woods Road, Ithaca, New York 14850, USA; 6Museum and Department of Zoology, Michigan State, University, West Circle Drive, East Lansing, Michigan 48824, USA; 7Museum of Natural Science, Louisiana State University, Foster Hall 119, Baton Rouge, Louisiana 70803, USA; 8Department of Zoology and Evolutionary Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario M5S 3G5, Canada; 9Environmental and Conservation Programs, Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, Illinois 60605, USA; and 10University of Alaska Museum, 907 Yukon Drive, Fairbanks, Alaska 99775, USA