1. The Institute for Bird Populations, PO Box 1346, Point Reyes Station, CA 94956 USA and La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095 USA
2. The Institute for Bird Populations, PO Box 1346, Point Reyes Station, CA 94956 USA
3. US Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Missouri, 302 Anheuser-Busch Natural Resources Building, Columbia, MO 65211 USA
4. USDA Forest Service, Plumas National Forest, 159 Lawrence Street, Quincy, CA 95971 USA