1. Arctic National Wildlife Refuge, U.S. Fish and Wildlife Service, 101 12th Avenue, Fairbanks, Alaska 99701, U.S.A.
2. Institute of Arctic Biology, University of Alaska Fairbanks, Box 757000, Fairbanks, Alaska 99775, U.S.A.
3. Division of Natural Resources, National Wildlife Refuge System, U.S. Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, Alaska 99503, U.S.A.
4. Present address: Western Alaska Landscape Conservation Cooperative, 1011 East Tudor Road, MS 281, Anchorage, Alaska 99503, U.S.A.
5. Division of Natural Resources, National Wildlife Refuge System, U.S. Fish and Wildlife Service, 101 12th Avenue, Fairbanks, Alaska 99501, U.S.A.