|Habitat and Ecology:
Western red-backed voles are found primarily in conifer forests, including lodgepole pine, Douglas fir, western hemlock, Sitka spruce, western red cedar, silver fir, grand fir, white fir, and ponderosa pine. They also occur in mixed forests, which include big-leaf maple and rhododendron. They apparently prefer dense forests with little ground cover, but with large-diameter rotten logs; generally in cool moist microhabitats in deep forest.
Decayed logs appear to be a critical component of suitable habitat, they use logs for cover (Tallmon and Mills 1994). Riparian areas are reported to be most favourable for reproduction, but uplands may have higher populations (see Alexander and Verts 1992). Sometimes found in manzanita brushlands in California. Logged and burned areas do not provide suitable habitat and may be temporarily inhabited (Alexander and Verts 1992). They nest underground in burrows (made by other animals), under logs, or under old leaves. In Oregon, home range size of four radio collared individuals was 606-3,418sqm (Tallmon and Mills 1994).
West of Cascade Range the voles breed throughout the year; populations in Cascade Range breed February-November (females pregnant or lactating mainly April-September). Gestation lasts 17-21 days. Litter size averages two to three (Maser et al. 1981, Alexander and Verts 1992). Individual females produce several litters per year. Western red-backed voles are active throughout the year. West of Cascade range, voles are active mostly at night; in the mountains, voles are active throughout the 24-hour cycle (Maser et al. 1981).
Their diet is dominated by fungal sporocarps (especially of hypogeous fungi) and lichens. Will sometimes eats green vegetation, grass, seeds, and insect larvae. May store fungi for later use. Forages mainly under cover. Predators include marten, short-tailed weasel, spotted skunk, bobcat, coyote, domestic cat and owls.