1. University of Alaska Museum, University of Alaska Fairbanks, 907 Yukon Drive, Fairbanks, AK 99775, USA
2. US Fish and Wildlife Service, Kenai National Wildlife Refuge, P.O. Box 2139, Soldotna, AK 99669, USA
3. Arctic Research Center, Aarhus University, 114, Bldg. 1540, DK-8000 Aarhus, Denmark; Department of Bioscience, Kalø, Aarhus University, Grenåvej 14, DK-8410 Rønde, Denmark