Microtus is a genus that includes around 62 Northern Hemisphere voles. These rodents are difficult to distinguish externally and identification is based on skeletal and dental features as well as habitat. They are commonly called meadow voles, field mice, field voles or meadow mice without trying to determine the species.
Most meadow voles create shallow underground burrow systems with many entrances. On the surface they create trail systems, usually under heavy grass cover, leading from one burrow entrance to another or from one bush or grass clump to another. These trails are like traffic lanes or roadways. When the ground is covered with snow, meadow voles make tunnels under the snow and thus travel on the surface of the ground protected from predators by the overlaying snow.
In the spring after the deep surface vegetation has lodged and the snow melts, the vole runways and tunnels are most visible.
These meadow vole runways are at Ash Creek Wildlife Area (Modoc County CA).