The Cinereus Shrew (Sorex cinereus), also known as the Masked Shrew, is a small shrew found in Alaska , Canada , the northern United States , and northeastern Siberia . This is the most widely distributed shrew in North America where it is also known as the Common Shrew.
It is grey-brown in colour with a light grey underside. It has a long tail which is brown on top and pale underneath with a dark tip. Its body is about 9 cm in length including a 4 cm long tail. It weighs about 5 g.
This animal is found in humid areas and damp northern forests. Its range extends further south along the Rocky Mountains in the west and the Appalachians in the east. This species was introduced into Newfoundland in the late 1950s.
It eats insects, worm, snails, small mammals, salamanders and seeds. It has a voracious appetite, even for a shrew, and can eat its own body weight in a day. Predators include larger shrews, hawks, owls, shrikes, snakes, herons, and foxes.
This animal is active day and night year-round. It digs tunnels but also uses tunnels created by other small mammals. It mates between spring and fall. 3 to 6 young are born in a nest under a log or in a stump. In the north, females have only one litter per year. This animal usually lives less than 18 months.