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]
Percentage by number
Species of plants
Quackgrass (_Agropyron repens_) 30
Speargrass (_Poa annua_) 1
California brome (_Bromus carinatus_) 1
Smooth brome (_Bromus inermis_) 1
Alfalfa (_Medicago sativa_) 25
Peppergrass (_Lepidium densiflorum_) 2
Cleavers (_Galium aparine_) 15
Wild lettuce (_Lactuca scariola_) 25