Several kinds of voles store food. Bailey (1920) wrote of the caches of Microtus pennsylvanicus in North Dakota, where, in one locality, this vole was known as the bean mouse. He stated that the Indians dug up beans (Falcata comosa) and the tubers of the Jerusalem artichoke (Helianthus tuberosus) which the voles had stored. Lantz (1907:17) found a cache of the roots of wild morning glory (Convolvulus sepium) laid away by Microtus pennsylvanicus. Nelson (1893:140) wrote that, as winter approached, Microtus operarius gathered small bulbous roots, sometimes storing a peck or more in a single cavity. Fisher (1945) in Missouri found a gallon of the fruits of the horse nettle (Solanum carolinense) stored in a hollow stump by the prairie vole. Kennicott (1857:99) found five or six quarts of roots of two species of spike-flower (Liatrus), Helianthus, and various grasses among the winter provisions of the prairie vole in Illinois.
Plants Used as Food and as Cover
[Table 3] lists, according to their families, the species of plants which the prairie vole was observed to use for food. The same species are sometimes used as cover. The majority of the plants are in three families: the grass family (Graminae), the pulse family (Leguminosae), and the composite family (Compositae).
The grasses that supply the voles' food and cover are mostly Poa (the bluegrasses) and Bromus (bromegrass, chess, or cheat). Poa pratensis is a common lawn and pasture grass, P. annua is a weed species. The bluegrasses begin to grow in late winter about Lawrence, Kansas, and they remain green until late in the fall. During this time, the voles eat the blades and heads of bluegrass, and make their runways under the culms. The prairie voles utilize several species of Bromus. Bromus inermis and B. carinatus are important range and pasture grasses, but japonicus is a weed of little or no economic value. These are soft, tender grasses, but, in contrast to the bluegrasses, they become dry in midsummer, and are then unsuitable as food. However, they continue to form a protection over the runways of the voles.
The legumes, which appeared to be most important to the prairie vole, are clover (Trifolium spp. and Melilotus alba) and alfalfa (Medicago sativa). These plants are common in both cultivated and feral states. They form a different type of cover from that made by grasses. Voles, living in clover and alfalfa, do not make runways as distinct as they do in grasslands. The clover and alfalfa plants are branched and of a spreading growth form, whereas the grasses have leaves which are appressed to the main stem. The individual grass plants grow close together, and a vole cannot run through grass without trampling some of it. As voles use the same paths repeatedly, the grass in their runs becomes flattened and dies. There is sufficient room between the stems of the clover and alfalfa plants to allow the voles to pass through without treading on the stems. In such a habitat, vole runways are poorly developed, and are difficult to find. Voles in grasslands feed in runways, as attested by the piles of cuttings found in the runways and the nibbled grass which borders them. Voles in clover or alfalfa feed at the bases of the plants wherever the plants may grow. In the latter type of cover the cuttings are rather evenly distributed.
Compositae formed a minor part of the cover in most of the habitats studied. Many grasslands have a stand of dandelions; sow thistle, wild lettuce, and ragweed were also common in some grasslands. The voles ate the leaves and sometimes the seeds and underground parts of these plants.
Table 3. Plants Used for Food by the Prairie Vole
| Graminae |
| Poa annua |
| P. compressa |
| P. pratensis |
| Bromus inermis |
| B. carinatus |
| B. japonicus |
| Andropogon furcatus |
| Agropyron repens |
| Setaria lutescens |
| S. viridis |
| Leguminosae |
| Melilotus alba |
| Medicago sativa |
| Trifolium spp. |
| Gymnocladus dioica |
| Solanaceae |
| Solanum carolinense |
| Boraginaceae |
| Galium aparine |
| Caprifoliaceae |
| Lonicera japonica |
| Compositae |
| Lactuca scariola |
| Sonchus arvensis |
| Ambrosia trifida |
| A. artemisiifolia |
| Taraxacum officinale |