Distances moved by small mammals as an apparent function of grid size

Abstract

Live traps were used on a 26x26 grid (14.1 ha) to determine the movement patterns of three species of smaii mammals in a lowland mesic-hardwood forest. Blarina brevicauda moved an average of 94.7 m between succesive captures, Ochrotomys nuttalli 72.8 m and Perornyscus gossypinus 54.9 m. These data are not consistent with Calhoun's theory of social dominance. Linear relationships are given for predicting home range size as calculated by several different methods from average distance between captures. A new way of depicting the distribution of distances between captures is given. Movements on the middle 16x16 grid compared to those on the 26x26 grid were 19.4010 shorter for 0. nuttalli and 25.1/o shorter for P. gossypinus. Longer movements are extending the area of effect around a census grid or line farther than might be expected from data collected on smaller study plots. Thus, an upward bias is introduced into most density estimates.