2018 年 49 巻 2 号 p. 53-62
We investigated conditions of stubble used by Bewick's Swans Cygnus columbianus for foraging at a rice Oryza sativa field zone of Nishikanbara area near Lake Sakata in Echigo Plain in Niigata Prefecture, where many Bewick's Swans winter. Field observations were conducted on 23th November and 21th December 2003, and 12th January and 15th February 2004. Swans seemed to select stubble on unplowed land where the degree of vegetation cover was low and the cover degree of scattered rice straw was high.