1. Alaska Center for Conservation Science, University of Alaska Anchorage, Anchorage, Alaska 99508, USA;
2. Alaska Cooperative Fish and Wildlife Research Unit, Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK, USA;
3. Alaska Cooperative Fish and Wildlife Research Unit, College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, USA;
4. U.S. Geological Survey, Alaska Cooperative Fish and Wildlife Research Unit, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA