Abstract
Wood mice were collected with snap traps in 30 different yong reforested forests of coniferous trees in Yamagata Prefecture during the period from May to November, 1967. The total number collected was 320, including 37 Microtus montebelli (MILNE-EDWARDS), 24 Aschizomys andersoni (THOMAS), 243 Apodemus speciosus (TEMMINCK et SCHLEGEL) and 16 Apodemus argenteus (TEMMINCK et SCHLEGEL). Generally speaking, in a forest in which A. speciosus was frequently found, M. montebelli was rare, and vice versa. The number of M. montebelli collected in the Dewa hills of western Yamagata Prefecture, was larger than that of the Ôu mountains in the east of the Prefecture. There was no relation between the altitude and the number of M. montebelli, or that of A. speciosus. On the contrary, A. andersoni was more frequently found in high level forests than in lower ones. A. argenteus was rare in the reforested area. However, some specimens of this species were found in a natural forest which is located at a higher level than the reforested area, the highest altitude of which was about 1, 000 meters.
