Sorex
vagrans
(Vagrant
Shrew)
Range:
The vagrant shrew is very
widely distributed in western North America, from Columbian Plateau, Snake River
Plains, and northern Great Basin, west to the Pacific Ocean, and east to the
Continental Divide. It has recently been found east of the Continental Divide
in southwestern Alberta.
Description:
The vagrant
shrew is medium sized; it appears reddish in summer, darker in the winter, and
like some other shrews, its tail is bicolored. Total length is 3.7 to 4.8 inches
(95 to 119 mm), tail length is 1.25 to 2 inches (34-51 mm), and it weighs 0.12
to 0.36 ounce (3-8.5 g).
Habitat:
It is found
in a wide variety of habitats such as forests, meadows, and riparian situations, but it is
often found in more arid areas including sagebrush steppe.
Diet:
Feeds primarily
on forest insects (eggs, larvae, pupae, and adults), slugs, and earthworms.
It may feed occasionally on salamanders and other small vertebrates.
Ecology:
Like all shrews,
it is active all year, and mostly at night. diurnal activity increases in
the spring. In a southern British Columbia study, mean home range was estimated
at 1039 m2 for nonbreeding, and 3258 m2 for breeding individuals. In an old
field community in western Washington, annual crude density was estimated at
36.6 shrews per ha (2.5 ac).
Reproduction:
Breeding may
occur from March to September, but most activity occurs in the spring, between
March and May. Litter size varies from 2 to 9 young (average 5.2). Gestation lasts approximately 20
days.
Conservation:
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Global Rank: |
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State Rank: |
S4 |
Important State References:
Rickard, W.H. 1960. The
distribution of small mammals in relation to climax vegetation mosaic in eastern
Washington and northern Idaho. Ecology 41: 99-106.