A Comparison of Habitat And Food of Two Species of Microtus

Abstract

A system of stratified random sampling was employed in the Terre Haute Quadrangle, Vigo County, Indiana, to obtain specimens of Microtus ochrogaster and M. pennsylvanicus for comparing habitat and food habits. M. pennsylvanicus occurred in fields containing at least 50% grasses and abundant cover. M. ochrogaster was found in areas with fewer grasses and less cover. M. pennsylvanicus was found to be closely associated with Poa and Muhlenbergia, while M. ochrogaster was closely associated with Poa, Muhlenbergia, Setaria and Trifolium. Important foods of M. pennsylvanicus were Poa, Panicum and Muhlenbergia comprising, respectively, 32.1, 24.7 and 14.6% of the volume of stomach contents. Important foods for M. ochrogaster were Poa, roots and Trifolium; these contributed 15.8, 10.0 and 9.7% by volume, respectively. M. ochrogaster ate a greater variety of foods than M. pennsylvanicus, probably owing to the greater numbers of species of plants in its habitat. M. ochrogaster ate 4.7% insect material and 0.6% Endogone; M. pennsylvanicus ate 3.6% insect material and 2.1% Endogone. The more abundant plants in the habitat were the most important foods. Ambrosia, Aster and Solidago were avoided.