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.
Cuttings
The voles seek particularly the tender heads of grasses and the terminal leaves of sweet clover (Melilotus alba). To obtain these parts, the voles begin by cutting through the base of the plant. The surrounding plants are often near enough to support the freshly cut piece in an upright position. The vole makes successive cuttings, 40 or 50 millimeters from the ground, until the desired parts of the plant are within reach. The cuttings that have accumulated at the base of the plant may be eaten, but frequently they remain as evidence of the vole's feeding activity.
On May 12, 1946, an analysis was made of the cuttings found in an area of alfalfa, grasses, and weeds. From [table 1] it may be seen that quackgrass, alfalfa, wild lettuce, and cleavers were common. In three nights 70 traps caught 8 prairie voles and 3 deer mice; no pine mice or cotton rats were caught on the area. The stomachs of the voles and the deer mice were examined, and only the stomachs of the voles contained green material. Analysis of the cuttings (see [table 2]) indicates that alfalfa was eaten in greater quantity than any other plant; it made up almost three quarters of the cuttings although but one quarter of the cover. All other plants occurred less commonly in the piles of cuttings than they did in the estimated composition of the cover. Grasses and wild lettuce were next to alfalfa in importance.
Table 1.—The Relative Abundance of Plants in an Area of Alfalfa, Grasses, and Weeds[A]
| Species | Percentage by number of plants |
|---|---|
| Quackgrass (Agropyron repens) | 30 |
| Speargrass (Poa annua) | 01 |
| California brome (Bromus carinatus) | 01 |
| Smooth brome (Bromus inermis) | 01 |
| Alfalfa (Medicago sativa) | 25 |
| Peppergrass (Lepidium densiflorum) | 02 |
| Cleavers (Galium aparine) | 15 |
| Wild lettuce (Lactuca scariola) | 25 |
Table 2.—Composition of Ten Piles of Cuttings[B]