Effects of Availability of Food and Interspecific Competition on Diets of Prairie Voles (Microtus ochrogaster)

Abstract

Analysis of fecal samples from experimental populations of prairie voles ( Microtus ochrogaster ) and meadow voles ( Microtus pennsylvanicus ) revealed that their diets strongly overlapped. Both species preferred dicots, but meadow voles ate significantly more mono-cots than did prairie voles. To test the hypothesis that interspecific competition for food influenced the diet of prairie voles, we examined the diets of prairie voles with and without meadow voles present. We found significantly more monocots in the diet of prairie voles when meadow voles were present, but only in early autumn when availability of high-quality food items was lower and densities of voles were higher. We conclude that variability in diets of voles can occur as a response to changes in availability of food, quality of food, and interspecific competition, the latter particularly when availability of high-quality food is relatively low and densities of voles are relatively high.