Illinois Department of Natural Resources
May 2020
May 1, 2020
A long-tailed weasel, Mustela frenata

Pop Goes the Weasel

By Laura Kammin

Most of us don’t know the words to the song, but I’d wager the tune is familiar (think of winding up a Jack-in-the-box). While the origins and meaning of “Pop Goes the Weasel” are a bit murky, it’s known as a popular English nursery rhyme and singing game, and in the 1850s it somehow managed to become a major dance craze in England and the U.S. Though the years the words of the tune have changed, to the point where speculating about their meanings is quite possibly more fun than the song itself. Rather than being about an actual weasel, one popular theory is that back in the day “pop goes the weasel” meant to pawn (pop) your coat (weasel) for a meal and a drink. However it got its start, the mystery surrounding the song seems fitting given the enigma that is its namesake—the weasel.

Even today there are still things we don’t know about weasels in Illinois. So perhaps the place to start is with what we do know. Illinois is home to two species of weasel: the least weasel (Mustela nivalis) and the long-tailed weasel (Mustela frenata). Both weasels have long, slender bodies, wide heads with small rounded ears, and short legs. But there’s ample difference in the size of the two species—the long-tailed weasel is two to three times larger than the least weasel. Long-tailed weasels are 11 to 17 inches long, weigh between 3 and 10 ounces, and their black-tipped tails are nearly half the length of their bodies. Least weasels can grow to 10 inches but weigh only 1 to 3 ounces. Their tails are less than a fourth of the length of their bodies and do not have a black tip. Typically, adult males are larger than adult females in both species.

An illustration of a silhouette of a six foot tall man next to the silhouette of a long-tailed weasel and the least weasel. The long-tailed weasel is about a half foot tall. The least weasel is less than a half foot tall.
Illustration created by Lynn Hawkinson Smith.

Despite their small size, weasels are fierce predators, and their coats help give them a seasonal advantage for blending in with their surroundings. In the summer, both species have reddish-brown fur with a yellowish-white throat, chest and underside, and the long-tailed weasel has a black-tipped tail. In the fall, weasels shed this coat and grow fur that is lighter, in many cases totally white (except for the black tip on the long-tailed weasels’ tails). In the winter, weasels found in northern Illinois are often white to help them blend into snow-covered landscapes, while those in southern Illinois may have patches of brown and white or they may retain their solid reddish-brown coat.

Least weasels are more specialized hunters than long-tailed weasels, focusing on voles and mice. Long-tailed weasels can take larger prey, and they will eat mice, rats, voles, squirrels, chipmunks, shrews, moles and rabbits. Less common foods include birds, bird eggs, snakes, frogs and insects. Both species kill more than they can eat and cache (store) the prey for later. In the open, small prey is killed with a few quick bites to the back of the neck. When a weasel finds prey in tunnels or underground burrows, they attack it head-on and the kill comes from a bite to the windpipe.

Weasels are active day and night, alternating between hunting and resting periods. Both species follow regular hunting routes, but usually only cover part of their home ranges during a single night. In past studies, males typically travelled farther than females.

The current distribution of weasels is generally, but not precisely, known. Previous studies found long-tailed weasels throughout Illinois and they are still fairly common. Least weasels are found in the northern half of the state and are not often seen, even though they may be common in the area.

Weasels are habitat generalists and prefer being near water. Long-tailed weasels tend to be more tolerant of people and will live on farms or the edges of suburbs. They are often found in forests, woodlands, thickets or brushy fence rows. Least weasels prefer more open areas such as meadows, grasslands or river bottoms. Weasel dens can be found in rock piles, junk heaps, abandoned buildings or burrows dug by other animals. The size of the area they live in depends on the amount of food found there. When small mammal populations are large, the home range of weasels is small, but their home ranges expand if food is scarce. Studies have shown that the home range of a long-tailed weasel can vary from 25 to 400 acres depending on food supplies.

Long-tailed weasels mate in July or August, and the young are born the following April or May. Females have only one litter per year, which range from one to nine young, though the average litter size is four to five. Only the female cares for the young. The young begin hunting with their mother when they are around six weeks and leave to find their own territories when they are just 11 to 12 weeks old.

A small dark brown weasel standing on a stump.
A least weasel, Mustela nivalis, standing on a stump. Photo by Javan Rhino, ZooChat.

Least weasels breed year-round. Females can have up to three litters per year if plenty of prey is available, and they also care for their young alone. The average litter is four to five young. Young least weasels develop quickly when food is plentiful—females born early in the year can breed as soon as four months of age. Neither species lives very long—typically less than a year.

In Illinois, least weasels and long-tailed weasels are protected as furbearers under the Illinois Wildlife Code. While weasels will readily kill poultry if they can get into the enclosure, they are often originally attracted to poultry pens by mice or rats. For tips on how to manage weasels check out Wildlife Illinois. If a weasel is causing damage, you may remove the weasel if you have received an animal removal permit from an Illinois Department of Natural Resources district wildlife biologist. Weasels may not be hunted in Illinois, but they can be trapped from mid-November through mid-February. Current trapping seasons and regulations can be found in the Illinois Hunting and Trapping Digest.

If you see a weasel in their natural habitat, enjoy the experience. You might get to see their classic bounding or loping movement—with their backs arched and their tails held straight out or slightly higher than their back. If you are quiet and observant, you might spot a weasel in the water or maybe even overhead. They swim well, especially the long-tailed weasel, and climb trees easily. But pay attention while you can as these secretive creatures aren’t likely to stick around long. Afterall, there’s hunting to do.

Laura Kammin is an Educational Programming Specialist with National Great Rivers Research and Education Center. She formerly held positions at Illinois-Indiana Sea Grant, University of Illinois Extension, Prairie Rivers Network and the Illinois Natural History Survey. She received her master’s degree in wildlife ecology from the University of Illinois, Urbana-Champaign.