Abstract
The burrow distribution of Mogera etigo was surveyed in three areas in the Echigo Plain, Niigata Prefecture, in 2011, and the results were compared with those of surveys conducted in 1995–1996 and 2003–2005. The first area was in the Mitsuke and Tochio area, which is isolated within the range of M. imaizumii. The second area was consisted of the paddy fields ranging from Gosen to Niitsu, at the outer edge of the main distribution of M. etigo. The third and final area was a small paddy field (about 600×850 m) situated to the south of Komagomi-Fujiyama in Niigata City, located in the main distribution. The range of M. etigo in the first area has been maintained with a small reduction. In the second area, some parts of the range have disappeared or have been replaced with that of M. imaizumii. The range in the third area has also been reduced. I conclude that the range reduction in the first and second areas has occurred due to interspecific competition with M. imaizumii and by habitat alterations such as the construction of deep concrete- or iron plate-sided ditches, a marked decline of grassy banks in ditches due to frequent spraying of herbicides, and the building of hard graveled farm road, etc. In the third area, the range has contracted due to habitat alterations.
