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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

February 1998

As hunter and hunted, weasels must be quick and wary to survive. Gregory Scott, ©1998

You little weasel!

Maligned and misunderstood, weasels deserve a closer look.

Christian W. Cold


As hunter and hunted, weasels must be quick and wary to survive.

© Gregory Scott

Hunters of mice || Weasel biology || How to find a weasel

Survival is the objective of the day, every day, if you are little. And danger is always nearby when you are a weasel.

Creatures larger than you are out there, listening, and watching with hungry eyes. You avoid their attention by remaining tentative; carefully choosing when to move. You travel about your 40-acre universe in a state of perpetual tension, keenly aware of every sound, every smell and every motion around you.

Finding a meal is work. Avoiding becoming a meal is even tougher. As both hunter and hunted, you bear the risks by constantly moving. If you tarry, you die; if your prey hesitates, it dies. Your quarry takes many forms – most are smaller than you, but similar in appearance. Their scent lingers everywhere, but they vanish when you arrive. Your prey cringes in terror in your presence...with good reason.

Weasels have an image problem. We are quick to condemn them as corrupt, greedy little villains who sneak around and kill with deadly efficiency for no reason whatsoever. We've historically viewed weasels as pests, varmints or scraps of fur only suitable for a decorative trim on collar or cuff. It's a wonder that weasels have endured such a hostile world.

In fact, weasels are marvelously successful. They persist by being alert, inquisitive, tenacious and most importantly, small.

Hunters of mice

Weasels are members of a large and diverse family of mammals known as mustelids, which include mink, martens, fishers and skunks. If you shake the family tree harder, badgers, wolverines and otters are also distant relatives. As a clan, the mustelids are typically slender, elongated animals with short legs, a small head and short fur. Their needle-like canine teeth are designed to pierce the throat and brain of small animals, particularly rodents.

The species name, Mustela, means "one who carries off mice," and all weasels are accomplished mousers. However, to reap the benefits of their small, dynamic world, the weasels can't afford to be picky eaters. The bill-of-fare includes chipmunks, ground squirrels, insects, small birds, frogs and snakes. Shrews form an important part of their winter diet. Though they occasionally eat fish, weasels are poor swimmers, paddling clumsily with their backs arched out of water.

Weasels have an earned reputation as fierce, efficient predators that will attack animals several times their own size. A four-ounce weasel can kill a four-pound rabbit. The weasel's habit of killing larger prey and killing several animals at a time stems from its habit of storing or caching surplus food for later use.

Weasels track mice through their winter runways and lairs.

© Gregory Scott
A weasel with prey – a mouse.

Small caches scattered about can provide a series of small meals. Incidents of wholesale slaughter in poultry yards are likely triggered when a weasel goes into "hunt mode" in the unnatural setting of finding several confined prey with no avenue of escape.

Weasel biology

Three species of true weasels live in North America. The largest, at 18 inches, is the long-tailed weasel (Mustela frenata). Long-tails occupy diverse habitats throughout the United States and into Central America. They appear to prefer patchy landscapes of mixed habitats intersected by streams and small rivers. The smaller short-tailed weasel (M. erminea) or "ermine" is found in heavily-forested areas and brushy areas of Canada, the northeastern states, the Upper Midwest and Northwestern forests. Smallest of the tribe is the least weasel (M. navalis), a pugnacious dynamo who claims the title as North America's smallest carnivore. The least weasel is infrequently observed in the marshes and damp meadow. I once inadvertently caught one in a repeating mouse trp at the Mead Wildlife Area in Marathon County in the Upper Great lakes region.

The pelts of all three weasels are brownish and are replaced by a winter white coat that begins to appear by the first of November. The long-tail and short-tail sport a black tip on their tails; an attribute which may confound the striking accuracy of avian predators. Hawks, owls, eagles, foxes, coyotes, bobcats, lynx and domestic cats will eat a weasel – provided they can catch one! The larger mustelids such as mink, marten and fisher pursue small weasels with frightful determination. Size and agility are not the weasel's only defense. A pungent musk, secreted from an anal gland, may repel or nauseate all but the most persistent of predators.

Weasels sexually mature before their first birthday. A typical litter of six or seven young is born each year and is cared for by both parents. Weasels reaching five to six years are regarded as fully mature. Individuals as old as 10 are considered ancient.

How to find a weasel

Weasels are easiest to see in winter when leaf cover is gone and a thin layer of tracking snow will show their whereabouts in the neighborhood. Weasels leave staggered pairs of little footprints placed in a bounding gait fashion. Look for sudden right-angle turns in the tracks that often disappear beneath the snow and reappear at a considerable distance.

Weasels hunt aggressively during the cold, hungry months of winter. Their intense curiosity and insatiable appetite leads them to range widely in a seemingly erratic fashion. They seldom travel far in any one direction. A weasel will stop to poke its little head into every hole, nook and cranny it can probe. Its slender body can squeeze into lairs and runways of mice. Within these subterranean passages the weasel's sensitive nose and ears will quickly locate the tenants.

Weasels often den in an abandoned (or usurped!) home of a chipmunk or ground squirrel, in a hollow log or under a pile of rubble. The nest chamber is often lined with fine grasses, feathers or the fur of the "former" occupants. Weasels are remarkably clean animals that will not defecate in their quarters. They designate a separate latrine area.

These sleek, little hunters are both feared and respected. If you are a weasel among mice, is it merely "a terrible efficiency" to be the animal that eats its neighbors? I think not. The weasel was designed by the limits of its environment to eat the flesh of others. It must kill to see another day. As humans, we tend to leave that grisly chore to the butcher, but the weasel assumes considerable risk and expends considerable energy just surviving.

The next time you get to see these ambitious little bundles of energy, take a moment to view the world from their perspective. Be thankful that at your comparative size, you can afford to wish them "good hunting."

Christian W. Cold is a DNR wildlife technician and educator stationed in Ladysmith.