1. Department of Natural Sciences and Environmental Health, University of South-Eastern Norway , Vestfold-Telemark , Norway
2. USDA Forest Service, Pacific Northwest Research Station , Corvallis, Oregon , USA
3. Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries, Wildlife, and Conservation Sciences, Oregon State University , Corvallis, Oregon , USA
4. Department of Fisheries, Wildlife, and Conservation Sciences, Oregon State University , Corvallis, Oregon , USA
5. Department of Biology, University of Portland , Portland, Oregon , USA
6. U.S. Geological Survey, Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries, Wildlife, and Conservation Sciences, Oregon State University , Corvallis, Oregon , USA