1. Department of Wildlife Humboldt State University Arcata CA 95521 U.S.A.
2. Department of Biology University of New Mexico Albuquerque NM 87131 U.S.A.
3. Present address: Department of Fish, Wildlife, and Conservation Biology and the Colorado Natural Heritage Program, College of Natural Resources Colorado State University Fort Collins CO 80524 U.S.A.
4. Natural Resources & Environmental Science University of Nevada Reno NV 89557 U.S.A.
5. U.S. Fish and Wildlife Service Sevilleta National Wildlife Refuge Socorro NM 87801 U.S.A.
6. Present address: San Francisco Bay Estuary Field Station Western Ecological Research Center, USGS Vallejo CA 94592 U.S.A.
7. Present address: Surprise Field Station, Applegate, Field Office, Bureau of Land Management, Cedarville CA 96104 U.S.A.