They have short slender bodies with a rust-colored back, light brown sides and underparts and a short thick tail. Their short ears are visible through their fur. They are 14 cm long with a 3.5 cm tail and weigh about 30 to 40 g. Their dental formula is 1/1, 0/0, 0/0, 3/3. They are active year-round, usually at night. They can cause damage to fruit trees and stored grains.
Northern red-backed voles are commonly found in northern shrubvegetation or open taiga forests. They also inhabit tundra. Northern red-backed voles are abundant on early successional sites as well as in mature forests. They occasionally inhabit rock fields and talus slopes.
Northern red-backed voles use surface runways through the vegetation as travel corridors. Nests are built in short burrows or under some protective object such as a rock or root. Northern red-backed voles are active all winter and construct long tunnels under the snow. Winter nests typically are placed on the ground among thick moss. Northern red-backed voles frequently invade houses during the winter.
Northern red-backed voles eat the leaves, buds, twigs and berries of numerous shrubs; they also eat forbs, fungi, mosses, lichens, and occasionally insects. Berries are generally the major food item in the diet of northern red-backed voles and are eaten whenever available. In central Alaska, West found that northern red-backed voles relied heavily upon the fruits of several berry-producing plants during all seasons. These included bog blueberry (Vaccinium uliginosum ), mountain cranberry, black crowberry (Empetrum nigrum ), comandra (Comandra livida ), and bunchberry. Northern red-backed voles primarily ate berries during the fall and winter. Lichens were consumed only during the winter and spring. In early summer, when berries are not available, mosses were eaten. The mid- to late summer diet of northern red-backed voles also included a large proportion of mosses, although berries were still the primary food.
Northern red-backed voles on the Kenai National Wildlife Refuge fed during the summer on berries of species such as mountain cranberry and bunchberry. They also ate fungi, succulent green plants, and insects. As fungi became plentiful late in the summer, they made up a large percentage of the diet. Mountain cranberry consumption declined as the summer progressed even though berry abundance increased. This suggests that fungi were preferred over mountain cranberries. The amount oftruffle in the diet remained constant throughout the summer.