1. Western Ecological Research Center, San Francisco Bay Estuary Field Station, U.S. Geological Survey, Vallejo, California.
2. Wildlife Health Center, School of Veterinary Medicine, University of California, Davis, California.
3. Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, California.
4. Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, St. Paul, Minnesota.
5. Western Ecological Research Center, Davis Field Station, U.S. Geological Survey, University of California, Davis, California.
6. Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska.