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The Shrew
Nature Bulletin No. 171-A November 28, 1964
Forest Preserve District of Cook County
Seymour Simon, President
Roland F. Eisenbeis, Supt. of Conservation
THE SHREW
On Veteran's Day one of our naturalists, turning over a sheet of
cardboard lying on the ground near a woodland briar patch, got a
glimpse of a tiny mouselike animal that darted away among the fallen
leaves. Beneath the cardboard was the empty nest of a family of
meadow mice, with their runways leading from it. There was some
chewed-up cockroaches and beetles, and a partly-eaten earthworm.
There were no mice. The shrew -- for it was a shrew -- had devoured
them.
In many places, shrews are among our most common mammals but
they are so shy and secretive, so small and lightning-fast, that few
people ever get a good look at one. There are many kinds which may
be divided into four groups: the long-tailed shrews, the short-tailed
shrews, the swimming or marsh shrews, and the "small" shrews. The
latter group includes the Pigmy Shrew and the Least Shrew which are
scarcely 3 inches long and the smallest of all mammals.
In the Chicago region the most common species is the Short-tailed
Shrew which has a total length of less than 5 inches including a one-
inch tail. With its soft velvety fur -- dark slaty gray above and lighter
underneath -- its tiny eyes and ears that scarcely can be seen, and its
long pointed flexible snout, the short-tailed shrew might be mistaken
for a small mole except that, like all shrews, it is a quick nervous
slender animal with mouse-like forefeet, built for speed and killing. In
contrast, altho both are insectivorous and closely related, the mole is a
plodder with powerful shovel-like forepaws, built for slow heavy work
underground.
The short-tailed shrew can and does burrow like a mole but the ridge
above its shallow tunnel is smaller and lacks the occasional humps
seen here and there on a mole "run". Most shrews, however, use the
deserted burrows of mice and moles, and the surface runways of
meadow mice. They are also found beneath stumps, fallen logs, roots
and rock piles; in rank growths of grass; and especially in leaf-covered
forest floors. They do not hibernate but are active all winter, mostly at
night, ceaselessly searching for food. Frequently, their tiny tracks are
seen on fresh snow and they will tunnel long distances beneath the
snow.
They have such ravenous appetites, which must be satisfied so often
and so fully, that a shrew has been known to die when deprived of food
for a few hours. A short-tailed shrew may eat more than its own
weight every 24 hours. The food of this species appears to be chiefly
insects, worms, centipedes, millipedes, spiders and land snails, but it
will kill and devour a full-grown mouse when hungry. Its mouth
bristles with tiny needle-sharp teeth. It attacks like an enraged fiend,
with a rapid chatter of squeaks pitched so high they can hardly be
heard.
The shrew, like the skunk, has anal glands by means of which it can
emit an unpleasant musky odor which repels many of its enemies. This
is especially true of the male shrew. Cats will kill them but rarely eat
them, However, they are preyed upon by weasels, mink, skunks and
foxes; and by snakes, hawks and owls, Large numbers of their bones
may be found in the pellets disgorged by owls.
Little is known about the home life of shrews: how many litters they
have each year, how many young per litter, or how they rear them. But
it is known that they have a unique method of moving their young.
When the nest is disturbed, the little ones grab the mother or one
another by the fur of the rump and are dragged, in a chain, away from
danger.
A shrew's hunting is incessant, relentless and deadly. It must be to
keep life in that tiny ferocious animal which is seldom still and always
hungry.
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