The influence of food availability on the white-footed mouse: populations in isolated woodlots

Abstract

The density and demography of populations of the white-footed mouse (Peromyscus leucopus) were monitored in two isolated woodlots for 29 months. After 14 months of preliminary trapping, supplemental food was provided on one woodlot for 15 months; the other remained as a control. Supplemental food had little influence on spring and summer densities although the onset of reproduction in spring was earlier and breeding occurred at a younger age in the experimental woodlot than in the control woodlot. Supplemental food strongly influenced autumn and winter densities, which reached much higher levels on the experimental plot than on the control plot. Higher densities were associated with better survival of nestling mice.Summer densities were limited by decreased survival and increased dispersal of young, and these were most closely correlated with densities of adult females. Therefore we suggest that summer densities were regulated by aggressive female behavior. In autumn the behavior of adult females changed, as indicated by a significant increase in home-range overlap among adult females, and both survival of young and total population densities increased. This behavioral change appears to be an adaptation to a seasonal change in predictability or food supplies. Unpredictable mast crops may provide either abundant or sparse food supplies in autumn, and neither can be defended efficiently.