Types of Cover
Prairie voles inhabit areas where the dominant plants in summer are clover or grasses or both. The lawn on the campus at the University of Kansas consists mostly of several kinds of grasses, but in some places alfalfa (Medicago sativa) replaces clover (Trifolium sp.), and in other places sedges (Scirpus spp.) are found in addition to the grasses. The grass is short; it is mowed to a length of 4 to 6 inches. Bluegrass (Poa pratensis) and crabgrass (Digitaria ischaemum) form most of the sod. Bluejoint (Andropogon furcatus) is common in a sparsely wooded part of the campus, an area which has many voles. Foxtail (Setaria lutescens and S. viridis) and prairie threeawn (Aristida oligantha) are also common on the lawn, but these become dry in late summer, and at that time supply neither food nor cover for the voles. The voles make well-beaten depressions in the sod, and the grass arches over them to form canopies.
In the winter, when the snow flattened the grass on the campus so that there were no longer protective canopies of blades over the runways of the voles, they migrated into areas of Japanese honeysuckle (Lonicera japonica). At this season the honeysuckle was their main food. In areas where this vine was not available, the voles abandoned their surface runways and remained below the ground, coming to the surface only under the protection of a blanket of snow. The voles returned to the grass and clover habitat in March and April in 1946.
One pure stand of Ladino clover in Jefferson County, Kansas, was studied in late November and early December of 1945. The clover was 2 to 4 inches high, and although it was the sole food of the voles, it furnishes but little cover. They were common here; 300 traps yielded 111 voles in two nights.