Cause of success in Rattus rattus control in urban area in Sapporo (Preliminary note)

Abstract

Among cities such as Sapporo, Sendai, Shinjuku, Yokohama, and Nagoya, where Rattus rattus infestations have been experienced from the 1970s, the problem has disappeared in Sapporo. The causes of the disappearance were analyzed with aerial photographs for commercial districts. The mean road space per hectare (±SD) for Sapporo was 0.401±0.129ha, which was not singnificantly different from 0.379±0.194ha for Shinjuku (p>0.50) but was larger than that for any others (p<0.01). A coefficient of variation 32.2% for Sapporo was apparently smaller than that for any other cities. Roads in Sapporo, therefore, are generally wide but those in the other cities are vary in size. Wide roads in Sapporo prevented the rats from moving between blocks, and as a result the rat population declined.