1. Laboratory of Boreal Forest ConservationField Science Center for Northern BiosphereHokkaido UniversityN.9W.9 Kita‐KuSapporo060‐0809Japan
2. Eastern Hokkaido Wildlife Research StationHokkaido Institute of Environmental Sciences2‐2‐54 UramiKushiro085‐0835Japan
3. Hokkaido Institute of Environmental SciencesN.19W.12 Kita‐KuSapporo060‐0819Japan
4. EnVision5‐2‐201, N.9W.4 Kita‐KuSapporo060‐0809Japan