To spot a weasel, you’d better look fast. These sleek little predators seem to be constantly on the move, which is one reason they can be tough to photograph. I caught this one the other day, as he ran up a tree to nibble on the remains of a deer rib cage I had wired to a branch.

Fortunately, I was sitting near the window, with my camera nearby, so I was able to snap a quick shot before he darted away.

That’s pretty much the life of the weasel. They have a super-fast metabolism that requires that they consume as much as half their body weight in prey every day. Mice and voles typically make up about three-quarters of their diet, so it’s easy to appreciate why these hardcore predators are the most feared creatures around, at least if you’re a mouse.

We have three species in Minnesota, the least weasel, the short-tailed weasel, and the long-tailed weasel, and all three of them can be found here in the North Country. The one pictured here is most likely a short-tailed weasel, which is the second largest of the three species, with a typical adult measuring about 12 inches long and weighing about four ounces. The least weasel is the tiniest, averaging just over six inches and weighing just 1.5-2 ounces. So while this fierce little predator has to eat half its body weight in a day, a single deer mouse will usually fit the bill.

When hunting is good, weasels will cache what they can’t consume immediately. I once found a weasel cache in our garage— a small box sitting on a shelf that contained more than a dozen dead, yet well-frozen, star-nosed moles. The largest reported weasel cache, discovered in Greenland, contained more than 150 lemmings.

Weasels are one of a number of northern species that change colors with the seasons. They’re brownish in the summer, with a lighter belly, but they change to winter white in the fall. I spotted a number of weasels this past November, when the late arrival of persistent snow cover left weasels and snowshoe hares dangerously exposed for a couple of weeks.

For weasels, the winter color change is probably as much about protection as it is a benefit for stalking prey. While they are voracious predators, their small size can leave them vulnerable to larger predators. Owls, hawks, pine martens, fisher, coyotes, and cats, will all prey on weasels if given the opportunity. In the wild, food is food, and most predators will take advantage of whatever comes their way.

In winter, the least weasel is all white, while the short and long-tailed varieties maintain a black tip on their tails.

Weasels are the smallest members of the Mustelidae family, which are often described as “mustelids” by biologists and naturalists. It’s a family of predators that includes marten, fisher, wolverines, and skunks, and like most mustelids, they share a common characteristic with skunks— namely the ability to expel a powerfully-smelly concoction from the musk gland under their tails, usually as a defense against would-be predators. It has a distinctly skunk-like aroma, which makes it risky to approach a weasel from behind.

This time of year, weasels spend much of their time under the snow, where they’ll pursue mice and other small rodents that remain active under the snowpack. That hunting habit may be a bit more challenging this winter, given the amount of crusted and icy snow that lies below the foot or so of fresh powder on top. That layer of crust is likely to prove challenging for many animals this winter. But look for weasels to find their way. Just look fast, because this is one animal that rarely slows down.