1. a Department of Wildlife, Fish, and Environmental Studies , Swedish University of Agricultural Sciences , SE-901 83, Umeå, Sweden
2. b Grimsö Wildlife Research Station, Department of Ecology , Swedish University of Agricultural Sciences , SE-730 91, Riddarhyttan, Sweden
3. c Forestry Research Institute of Sweden, Uppsala Science Park , SE-751 83, Uppsala, Sweden
4. d Faculty of Forestry and Wildlife Management , Hedmark University College , Evenstad, NO-2480, Koppang, Norway