Shrews have tiny eyes, almost concealed in the fur. The body is slim; the nose elongate and pointed. The legs are short and the feet small and weak. The fur is short but soft and posteriorly directed. The cinereous shrew, for example, is about 4 inches in length, of which the tail comprises 1-3/4 inches. The upper parts are dark grayish brown and the underparts dull gray.
Shrews of the genus Sorex are cosmopolitan in distribution. In North America they range from the arctic south to Central America. Three subgenera are recognized by [Jackson] (1928: 27), all three of which are represented in the state of Washington. The twelve subspecies present occupy numerous habitats, and their ranges include almost all of the state.
[Jackson] pointed out (1928: 1) that "No other group of American mammals having a wide distribution, and in many localities an abundance of individuals, is so little known to the nonprofessional mammalogist as the long-tailed shrews." In Washington, especially in the coastal area of western Washington, shrews are widespread and abundant in many habitats. In some places they are the most common mammal present. In spite of this their presence is often unsuspected by persons that are otherwise alert to the animal life around them. This is even more surprising when one takes into account the facts that long-tailed shrews are diurnal as well as nocturnal and are less apt to detect the presence of man than are most other species of mammals.
An important factor making long-tailed shrews inconspicuous is their small size, and contributing factors include their rapid movements and dull colors. On several occasions the writer, after seeing a long-tailed shrew vanish soundlessly under a log or into a patch of dead leaves, was left wondering if one actually had been seen or if instead his imagination had conjured up an animal from a dust mote or wind-blown leaf.
The environment of the long-tailed shrews, except for the water shrews, is the zone at the very surface of the earth, just beneath the layer of moss, grass, dead leaves, and decaying vegetation. The removal of the covering vegetative layer reveals a maze of tiny tunnels, the branchings and complexities of which are infinite. Tiny traps baited with oats or meat and set in these runways catch the long-tailed shrews that inhabit them.
The food of long-tailed shrews is varied. It is principally soft-bodied insects, insect pupae, and earthworms. At times a considerable quantity of soft vegetation and some seeds are eaten. Recent studies ([Moore], 1940: 1942) have shown that by destroying seeds some shrews may adversely affect the reforestation of some coniferous trees. Shrews readily eat meat, and often destroy the small mammals, including other shrews, taken in the mammal collector's traps.
[Hamilton] (1940: 485) found that in one species of long-tailed shrew in the United States individuals rarely lived more than one year. This seems not to be true of at least some of the species found in Washington.
Parasites, internal or external, are not commonly found on long-tailed shrews. They are regularly eaten by owls and snakes, but most carnivorous mammals, though they readily kill them, rarely eat them.
Sorex cinereus Kerr
Cinereous shrew
The cinereous shrew ranges over most of Alaska, Canada and the northern half of the United States. A number of subspecies have been described, of which two have been reported from Washington. The cinereous shrew is of medium size and difficult to distinguish from the dusky and wandering shrews, especially in eastern Washington, without studying the skulls. In cinereus the fourth unicuspid tooth is smaller than the third; in vagrans and obscurus it is larger. The relatively narrow rostrum of cinereus also serves to separate it from the other two species.