The changing natural world at our doorsteps | Illustration and text by Patterson Clark
May 25, 2010
In every garden a shrew
Young short-tailed shrews are leaving the nests where both parents raised them this spring.
Born in late March and reared in an underground nest of shredded vegetation, a shrew pup and its half-dozen siblings will reach sexual maturity before summer. Shrews breed through September.
Highly abundant in cities and suburbs but seldom seen, short-tailed shrews thrive in vegetable and flower gardens, where they cruise through an elaborate network of passageways at the soil surface.
Shrews eat as much as three times their weight every day. Their diet includes earthworms, insects, slugs, nuts, berries and the shrew equivalent of big game: mice and voles, both of which are larger and heavier than they are.
A shrew's limited sense of smell and sight is offset by its use of echolocation. As with bats, shrews emit a series of ultrasonic clicks that bounce back, enabling them to navigate through dark spots and locate food.
A short-tailed shrew uses it sharp, red-tipped teeth to deliver a poisonous bite that incapacitates its prey. Shrews tend to hoard their food and can store enough stunned snails and beetles to provide a chance at surviving the winter.
Humans are too large to be paralyzed by the toxin in a shrew's saliva, but a small wound from a shrew bite can remain painful for days.
SOURCES: University of Michigan; National Museum of Natural History