Western meadow vole
The western meadow vole (Microtus drummondii) is a species of North American vole found in midwestern and western Canada and the United States, and formerly in Mexico. It was formerly considered conspecific with the eastern meadow vole (M. pennsylvanicus), but genetic studies indicate that it is a distinct species. Distribution It ranges from Ontario west to Alaska, and south to Missouri, north-central Nebraska, the northern half of Wyoming, and central Washington south through Idaho into north-central Utah. A disjunct subset of its range occurs from central Colorado to northwestern New Mexico. An isolated population was formerly found in Chihuahua, Mexico, but has since been extirpated. The United States portion of the Souris River is alternately known as the Mouse River because of the large numbers of field mice that lived along its banks. Plant communities In eastern Washington and northern Idaho, meadow voles are found in relative abundance in sedge (Carex sp.) fens, but not in adjacent cedar (Thuja sp.)-hemlock (Tsuga sp.), Douglas-fir (Pseudotsuga menziesii), or ponderosa pine (Pinus ponderosa) forests. Meadow voles are also absent from fescue (Festuca sp.)-snowberry (Symphoricarpos sp.) associations. Moisture may be a major factor in habitat use; possibly the presence of free water is a