Movements of Microtus pennsylvanicus in Relation to Depopulated Areas

Abstract

Movements of individual voles were studied before, during, and after decimation of a segment of five Microtus pennsylvanicus populations. On each occasion a field was live-trapped and voles were marked; a central area of each field was then snap-trapped for 28 days. Snap-trap data demonstrated that 50% of all voles were live-trapped. Less than 11% of the marked voles moved into the central area after day three of the snap-trap period. Longer movements into this area were found with passage of time. A greater percentage of voles moved in from areas of high population densities, but distance of movement did not depend on density. Nonpregnant females moved farther than did pregnant females, but no significant difference was found between the number of each sex that moved into the area. From 80 to 100% of the residents were snap-trapped in the first three days. Two weeks were necessary to trap a number of incoming voles equal to the number of residents killed on that area. Time durations of stationary home ranges are presented. Comparisons are made between movements of Microtus and Peromyscus , and the effectiveness of trapping procedures is discussed.