Family: Soricidae, Shrews view all from this family
Description A very small shrew. Brownish above; belly silvery or grayish. Long tail brown above, buff below; tail tufted, with terminal hairs of underside dark. Third and fourth unicuspids usually about same size. L 2 3/4–4 3/8" (71–111 mm); T 1–2" (25–50 mm); HF 3/8 –1/2" (10–14 mm); Wt 1/16–1/4 oz (2.4–7.8 g).
Similar Species In East, smaller Southeastern Shrew has shorter, less-hairy tail and shorter, less-pointed snout. In West, Vagrant and Dusky shrews usually have smaller third unicuspid than fourth.
Breeding Mates from spring to fall. Gestation about 18 days. Each female probably has only 1 litter of 2–10 (usually 5–7) young.
Habitat Numerous habitats; most common in moist fields, bogs, marshes, and moist woods. Where Hayden’s and Masked shrews occur together, Masked inhabits woody or high-grass areas, Hayden’s short grass.
Range Throughout most of Canada and n U.S. south to Washington, Idaho, sc Utah, nc New Mexico, and Nebraska in West, and to Illinois, n Kentucky, and throughout Appalachians in East.
Discussion One of the most widely distributed mammals in North America, this small, primarily nocturnal shrew is secretive and rarely seen. Although all shrews are noted for their large appetites, the Masked Shrew is particularly voracious. Its daily consumption of moth and beetle larvae, slugs, snails, and spiders often equals or exceeds its own weight. Like other shrews, the Masked Shrew does not hibernate; it seeks out dormant insects for sustenance even during the coldest part of winter. It makes a nest of leaves or grass under a log or in a stump or clump of vegetation. The young are born blind. At 18 days, their eyes open; at 19 days they are weaned and become independent. Few young shrews are noted in the field because they reach nearly full size before leaving the nest.
