Date of this Version
Free-ranging, sexually mature meadow voles (Microtus pennsylvanicus) were tracked using radiotelemetry from June through August 1974, 1975 and 1978. Up to 20 voles were monitored concurrently to derive estimates of intraspecific spacing and natural predation in an effort to clarify processes involved in the limitation of population growth. The daily ranges of the males, as compared to those of the females, were larger, more variable in size, and changed location more from one day to the next. Adult females usually maintained territories free of other females; males overlapped considerably among themselves. Males temporarily moved into the areas occupied by estrous females, indicating intrasexual competition among males for access to receptive females. Predation, primarily by three snake species, the domestic cat, and weasels, accounted for the deaths of 30 of 93 voles monitored with radiotelemetry during the three summers. The intensity of predation varied with the reproductive state of the meadow vole, occurred in bursts through the summer, and was selective for voles living nearer suboptimal habitats. M. pennsylvanicus are socially organized into territorial, maternal-young units during the breeding season. By being territorial, breeding females set in motion a sequence of behavioral events that results in population limitation and potentiates population cycling.