Montana Field Guide

Masked Shrew - Sorex cinereus

A medium-sized shrew (adults usually 9-11 cm total length, tail 35-45 mm, 3-6 g) with a sharply pointed snout, beady eyes, and small ears nearly hidden in the fine soft pelage; dorsal pelage varies from dark brown to gray, depending on the season and location; five small unicuspidate teeth behind the upper incisors (the fifth is minute, the fourth generally is smaller than [less commonly equal to, or sometimes larger than in subspecies OHIOENSIS] the third, and both of these are smaller than the first and second; tips of teeth are dark chestnut; feet are delicate, with slender weak claws; condylobasal length of skull 14.6-16.9 mm; maxillary breadth less than 4.6 mm; posterior border of infraorbital foramen even with, or anterior to, plane of space between M1 and M2 (Armstrong 1987, Hall 1981, Godin 1977).

Generally paler and smaller than s. fumeus (95-129 mm total length) (godin 1977). see hall (1981) for a (somewhat outdated) key to north american species of sorex. see carraway (1995) for a key to western north american soricids based primarily on dentaries.

Montana Range

Nonmigratory.

Coniferous forest (Junge and Hoffmann 1981). In western Montana, where SOREX VAGRANS also occurs, S. CINEREUS is usually restricted to drier coniferous forest habitat (Hoffmann and Pattie 1968).

Invertebrates, salamanders, small mice. In winter, seeds may be main item in diet (van Zyll de Jong 1983).

Populations fluctuate year to year. Birds, snakes, and mammalian carnivores are predators (van Zyll de Jong 1983).

Probably polyestrous. Spring (April)-autumn, altricial young born in a spherical nest of dry vegetation (van Zyll de Jong 1983).