Shrews (Sorex spp.) are Washington's smallest mammals; the pygmy shrew is no bigger than your entire thumb. Shrews are also one of our most common mammals, inhabiting areas from sea level to high mountain meadows. Even so, they are surprisingly one of our least well-known mammals.
Shrews are mouselike in proportion, but differ from mice in having long, pointed muzzles and minute eyes. Most are less than half the size of adult mice, and blackish or brownish in color, with a pale-colored belly (Fig. 3).
Nine species of shrews are found in Washington. The 4-inch long vagrant shrew (Sorex vagrans) is the most widespread species and is found in marshes, wet meadows, forests, streamsides, and gardens throughout the state.
Shrews prefer moist environments because their high metabolic rates create high moisture requirements and they can easily become dehydrated. Moist environments also tend to have a diverse and abundant food supply.
Shrews are preyed on by owls, snakes, and Pacific giant salamanders. Domestic cats, opossums, foxes, and similar-size mammalian predators kill but may not eat shrews, presumably because, when frightened or agitated, shrews produce a musky odor from their anal glands.
Shrews are rarely considered pests. They will occasionally enter homes but seldom cause any trouble other than perhaps startling a resident. Techniques used to mouse-proof structures will also exclude shrews.