Capture-recapture work was performed in 1970 and 1971 with Microtus montebelli seeking to disclose the edge effect subjects. For the purpose, in principle, it is needful for us to approach the reality of home range in size and shape. As the result of these studies, it has been established that the method using observed range length and width is highly available for searching after natural ranges and that the natural range of the voles (Microtus and Clethrionomys) is ordinarily on the order of 0.05 for females and of 0.10 for males in acres and generally oblong in shape such as its eccentricity is about 0.80. Several tentative means have been thus far presented for determining the area of effect by sampling, but the process of Dice's assessment line has proved to be most useful in its sureness and simplicity; its empirical validity could be confirmed through mediation of Marten's notion (1972) and Wlerzbowska's (1972).