Forest Preserve District of Cook County, Illinois
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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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