Shrew or Mole? Mouse or Vole?

Illustration by Adelaide Tyrol

When it comes to nature, we tend to stuff things we don’t know into pigeonholes that are already defined by the familiar. If someone tells me their cat has left a “present” of a dead “mouse” on the doorstep, I ask the usual questions: How big is it? What color is the fur? How long is its tail? What size are the eyes and ears? How pointed is its nose? Chances are that it’s not a mouse.

Often, here in northern New England, the deceased is a 4- to 5-inch-long northern short-tailed shrew, with its dark gray fur, inch-long tail, pinpoint eyes, sharp nose, fur-covered ears, and stubby legs bearing sharp claws for digging. And the cat is not necessarily leaving the shrew as a gift: short-taileds have glands on the hips and belly that emit such a strong, musky odor that most predators can’t stomach the idea of eating one. Snakes and owls actually partake of the pungent, as do other shrews, which have a poor olfactory sense.

With a metabolism that is 60 times the rate of a human’s, shrews are more often the predator than the prey. Wielding sharp teeth, short-tailed shrews can consume more than their own weight each day, so they are not fussy about who or what they eat. Insects, worms, and spiders are fair game, as are centipedes and salamanders. Meadow voles are a popular item on the menu, along with mice, snakes, small rabbits, the hatchlings of ground-nesting birds, and even other shrews. Unique among mammals, the bite of a short-tailed shrew contains a poison that can paralyze and even kill its prey.

As they tunnel, short-tailed shrews navigate like bats and dolphins: they emit ultrasonic clicks that reflect back to their ears to create an aural picture of the surroundings. From as far as 2 feet away, a short-tailed shrew’s echo-location helps it to find solid objects, holes, and places where grass may block a runway. Their sixth sense may even serve to identify predators and prey.

When the north wind blows, the short-tailed shrew’s short summer coat grows longer and turns a darker shade of gray, making it appear very mole-like. But moles are larger and more robust insectivores with powerful front shoulders and outsized front feet and claws. The star-nosed mole has a 3-inch-long tail and an unmistakable sunburst-shaped nose bearing 22 pink rays that encircle the tip. Another species of local mole, the hairy-tailed mole, is about 6 inches long. They have a short, furry tail, and their backs are covered with fur that ranges from dark gray to black. Each day, one of these feisty, 2-ounce critters can eat more than its own weight in earthworms, snails, millipedes, slugs, and insects. Its winter tunnels lie 10 to 20 inches beneath the surface.

The short-tailed shrew most closely resembles yet another species, the meadow vole, but voles are tawny brown in summer, turn grayer in winter, have a blunt nose and a tail that ranges from 1 1/2 to 2 1/2 inches long. They have beady black eyes, short, rounded ears, and chunky bodies that measure 6 to 7 1/2 inches with the tail. Voles tunnel below the surface and create runways in the thick grass. Their food includes grass, seeds, grains, and tubers. Mice are blamed for much of the damage done by voles, which eat prodigious amounts of roots, countless flower bulbs, and are so fond of bark that they often girdle and kill young shrubs and trees. And meadow voles can produce up to 17 litters each year!

If you look carefully at short-tailed shrews, moles, and voles, they don’t resemble mice,  which have large, prominent eyes, big ears, and tails about as long as their bodies. Our two common species are the white-footed mouse and deer mouse. White-footed mice are reddish brown, with a dark patch running along the back. Deer mice have brownish-gray fur and are nearly 7 to 8 1/2 inches long, including the 3- to 4-inch-long tail. Mice eat as much as a third of their weight in food each day, including lots of seeds, grains, nuts, and fruits. A third or more of their diet consists of animal foods such as small insects, grubs, and worms. They cache sizeable stores of food as autumn days grow short.

When a wintering “mouse” appears in one of the live traps I set in our porous, Civil-War-era house, I look closely. Shrew? (Sharp nose, short legs and tail.) Mole? (Big shoulders, claws, and a longer tail.) Vole? (Brown, big, blunt nose.) Mouse? (Big ears and eyes, very long tail.) I handle them carefully on our journey of at least 2 miles, the minimum distance from which they won’t later return. And I am especially careful when moving a shrew so as to avoid its painful, toxic bite.

Michael J. Caduto is an author and ecologist who lives in Chester, Vermont.

 
Discussion
  1. Nancy Goodenow → in United States
    May 30, 2013

    I had a mole/mouse brought into the house this a.m. by a small dog.  It was wet, dead but not mutilated.  It is very small.  I photographed it pretty well up close.  The head is more pointed than I have seen on mice here in Oregon, USA.  The teeth are black.  Would you like to see the photos…I can email them.  It is very small.  I photographed in next to a penny.

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