Illinois Natural History Survey - University of Illinois

Species Spotlight: Short-tailed Shrew

While Shakespeare's farcical portrayal of the ill-tempered Kate in Taming of the Shrew may raise a few politically correct eyebrows today, a firsthand encounter with the tiny but ferocious short-tailed shrew leaves little doubt why the term "shrew" is applicable to someone with a nasty disposition. Even old rough-and-tumble Teddy Roosevelt was impressed with the aggressive demeanor of his pet shrew, writing "certainly a more bloodthirsty animal of its size I never saw."

One of the most ubiquitous and abundant mammals to inhabit Illinois and Indiana, the short-tailed shrew is seldom seen in its natural habitat and is most likely to be encountered when it becomes "something the cat dragged in." If they are seen, shrews are often mistaken for mice or voles because of their small size, but they are not rodents, belonging to a separate mammalian order, the Insectivora. Weighing only an ounce and stretching a mere five inches, the short-tailed shrew is still the largest shrew species found in our area. Its cylindrical body is covered with short, velvety gray to black fur; but the long, pointed, flexible nose, tiny beady eyes, and small ears hidden in its thick fur give it a somewhat demonic appearance. Add to this a distinctive, but mysterious, red or brown pigmentation of their teeth and it's no wonder the shrew has historically received more than its share of bad press.

shrew.JPG
Northern short-tailed shrew, Blarina brevicauda .

Just about any habitat can sustain a population of shrews: upland or bottomland forests, grasslands, weedy fields, wetlands, and occasionally even buildings. Population densities most certainly vary among these habitats, but can reach 80 per acre in moist forests with a thick layer of leaf litter and numerous logs. Shrews are active year-round and spend most of their time in underground burrows or scurrying through grassy tunnels in open fields or through leaf litter on forest floors. Because of poor vision, they rely on their sensitive snouts and abundance of whiskers to navigate; adding to their mystique they also use a form of echolocation, more often associated with bats and dolphins.

Female shrews construct a bulky, oval-shaped nest of partly shredded leaves and grasses beneath a fallen log or stump. The young are born in the nest from early spring until late September with usually four to six per litter. Three to four litters are produced per year. When born the shrews are naked and their eyes and ears are closed. They are the size of a honeybee, but within one month they are half grown.

Shrews are without a doubt one of the most ferocious mammalian predators--as one naturalist put it, "the tigers of the small animal world." But thankfully, due to their small size, their prey consists largely of earthworms, snails, slugs, insects, and other invertebrates. Occasionally they will resort to small amounts of plant material, but the real "beasts" are more likely to take on other small rodents, salamanders, and snakes. To further add to their charm, shrews are one of the few venomous mammals in the world. Their saliva contains a powerful toxin that can cause a painful reaction in some humans, but is more useful in immobilizing its prey. The immobilized prey can be cached alive to serve as a larder of food that will remain fresh for several days.

Some shrews do end up on the wrong end of the food chain. Owls, hawks, snakes, and weasels are known to feed on shrews, but other predators make the kill, then leave them uneaten--like those gifts the cat sometimes leaves on the doorstep. Though the shrew paid the ultimate price, it gets the last laugh--a foul, musky odor produced by scent glands on its flanks gives it a taste as bad as its personality.

Susan Post and Charles Helm, Center for Economic Entomology; Joyce Hofmann, Center for Biodiversity



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