京都市岩倉に棲息するハタネズミの繁殖状況 REPRODUCTION OF JAPANESE FIELD VOLES, MICROTUS MONTEBELLI (MILNE-EDWARDS), AT IWAKURA, KYOTO, JAPAN
Reproduction of Microtus montebelli inhabiting cultivated lands was studied bi-monthly during the period from May, 1971 to March, 1972. The population was characterized by two main breeding seasons, in spring and fall, with sporadic breeding during winter. The average embryosize per pregnant female, based on 40 specimens captured during one year, was 5.1. The largest mean embryo-size appeared in September. The pattern of change in the male breeding rate and mean testis length showed similarities to that in female breeding rate, pregnancy rate and mean embryo-size. From the comparison of the breeding season in Kyoto with that in other localities, it is suggested that high temperature exerted a restraining influence on the breeding of the vole in summer. The seasonal change of embryo-size in Kyoto differed from that in Iwate. The reasons for the difference are discussed.
日本生態学会誌 26(2), 107-114, 1976