Shrew (Soricidae), family of small insectivores represented today by approximately 250 species worldwide, 16 in Canada.
Shrew (Soricidae), family of small INSECTIVORES represented today by approximately 250 species worldwide, 16 in Canada. Shrews are small (35-180 mm long) and have short legs; a well-developed tail; long, pointed snout; small eyes; and ears usually partially hidden in soft, often velvetlike fur. The long, narrow, somewhat conical skull lacks zygomatic arches (bone arches in skull extending beneath the eye sockets).
The unique dental structure has hooklike upper incisors that, with the elongated, horizontally projecting lower incisors, form a tweezerlike organ with shearing tips, perfectly adapted for grasping and cutting INSECTS. The molars are suited to piercing the tough external skeleton of insects and shredding food. The short-tailed shrew has a venemous bite.
Shrews are continually active and, to maintain their high metabolic rate, daily may consume their own weight in insects, other small animals and vegetable matter. If deprived of food, they die quickly.
Distribution and Habitat
Shrews occur throughout Canada except in the arctic islands. Most species live in leaf litter and dense ground cover of woods and in open grassland and TUNDRA. Short-tailed and least shrews (Blarina brevicauda, Cryptotis parva) dig well and spend much time underground. Gaspé and rock shrews (Sorex gaspensis, S. dispar) are largely restricted to talus slopes. Water shrews (S. palustris, S. bendirii) are semiaquatic.
Reproduction and Development
Little is known about reproduction in most native shrews. Available information indicates that shrews mate from late winter or early spring to late summer or fall, and give birth to litters of from 3-10 naked, blind young after a gestation of 2-3 weeks.