Abstract
We collected records of the native sable Martes zibellina and the introduced marten M. melampus in Hokkaido from 2000 to 2014 to assess the latest distribution of the two species. We found that the marten was widely distributed in the southwestern part and that the sable in the rest of Hokkaido. These two areas were divided by the Ishikari Lowland, which is mostly composed of non- or poorly-forested areas that stretch from the Ishikari Bay in the north to the Pacific Ocean in the south. Records of the sable were also obtained from three areas in the Ishikari Lowland. They were all located in the west side of the lowland with rivers as a reference line. Based on these results and some additional old records, we suggest that: 1) the marten expelled the sable in expanding its range; 2) the marten may not have reached the western edge of the lowland in the south of the watershed, but it will not be long before it does so; 3) the marten might be able to cross the lowland in the south of the watershed and expand its range to the east.
