7 Fierce Facts About Weasels

Weasels may look cute and cuddly, but trust us: you don't want to get too close to these little beasts. Here are seven things you might not know about the fierce furballs.

1. They’re Killing Machines

They might have cute little faces, but weasels are also bloodthirsty. It’s a matter of necessity: they have super-fast metabolisms and need to kill and eat about half their body weight every day. As a result, they’ve become fearsome hunters. The weasel corners and grabs its prey, wraps its muscular body around the animal to immobilize it and then delivers a single killing bite to the back of the head, puncturing the skull or spinal cord. You know what other animal kills like that? The jaguar. 

The weasel’s bloodlust is instinctual and triggered by movement. Even on a full belly, a weasel will kill anything that moves and looks like prey. And to the tenacious weasel, pretty much everything looks like prey. Tiny weasels have been seen killing and carrying off animals twice, four times, and even 10 times their size. 

2. They Save Their Leftovers

When prey is plentiful, a frenzied weasel will often kill much more than it can eat. This is no problem; the leftovers will keep. Weasels evolved in cold climates, and learned to use this to their advantage. They dig little underground caches near their den entrances and keep them stocked with leftovers. In the winter, when it’s too cold to go outside, a weasel can just go to the fridge and pull out yesterday’s vole or that extra mouse from last week.

Like any refrigerator, the caches can occasionally get out of control. Scientists found one cache in Greenland stuffed with the carcasses of almost 150 lemmings. 

3. They Do a War Dance

Weasels, stoats, and even domesticated ferrets all perform a hilarious “weasel war dance” when they’ve got their prey cornered. Scientists aren’t totally sure why they do this. One theory is that the weasel’s wacky twisting, hopping, and darting around distracts, confuses, or even hypnotizes prey animals. In one case, researchers concluded that a number of rabbits killed by stoats had actually “died of fright” after being subjected to the weasel war dance. 

But sometimes there’s no prey in sight, and a weasel’s just dancing on its own. With no audience and no chance to kill anything, weasels may dance for the same reason we do—because it’s fun.

4. They’re Not Afraid to Fly

Remember that viral picture of the weasel “riding” a woodpecker? That “ride” was probably more like a hijacking. There’s a long, rich history of weasels attacking birds, including kiwis, magpies, owls, herons, and even birds of prey, as Dr. Carolyn M. King observed in her article “Weasel Roulette”:

[A] British observer named Anderson witnessed a buzzard, or European hawk, swoop down, pick up a weasel from the ground, and then fly off to its usual feeding perch. But within seconds the buzzard's smooth flight turned into an ungainly struggle, and it eventually fell to the ground. Anderson ran to where it fell, and there was the buzzard lying dead on the ground, its underparts bloody, and the weasel still gripping its breast with meshed teeth.

Naturally, these gambits do not always work out in the weasel’s favor, hence the term “roulette.” (On a related note, a weasel's lifespan is a mere 1 to 2 years in the wild, for obvious reasons.) But when they do? Watch out.

5. They Deploy Stink Bombs

By now, you’ve probably realized that it’s a bad idea to cross a weasel. On the off chance you aren’t totally sure, consider the following: a cornered weasel can blast its opponent in the face with a thick, oily, yellowish fluid that positively reeks. Like its cousin the skunk, the weasel brews up tablespoons of this special “musk” in little pouches under its tail, then shoots it out on special occasions. Do not stick around during one of those occasions.  

6. They’re Legendary Monster Slayers

The Algonquian-speaking peoples of Canada and the U.S. tell stories of the windigo (also spelled wendigo and witiko), an enormous, man-eating monster. According to legend, the windigo is cursed with an insatiable hunger. Eating does not satiate the beast; instead, with every meal, the monster grows in size and becomes even hungrier. The windigo stalks from village to village, devouring the inhabitants and wanderers along the road. No man can destroy him. 

One day, the windigo captures a traveler. He sends the terrified man out to find sticks for his own cook fire. Along the way, the man encounters a weasel and begs it desperately for help. The man returns to the monster with the weasel hidden in his clothing. As they approach, the weasel rushes at the windigo and climbs into his anus. The windigo begins to look quite ill, and soon falls down dead: the tiny, brave weasel has eaten his heart from within.

7. They Glow Purple Under a Black Light (Allegedly)

Weasels were plentiful in Pennsylvania in the early 1950s, but they weren’t welcome. After the Pennyslvania Game Commission offered a bounty for every weasel pelt, they found themselves inundated with fur. The region was home to three weasel species, but once the weasel's tail had been removed, the pelts all looked pretty much the same. So how could they figure out which species a pelt belonged to?

One employee thought he had the answer. In 1953, Roger M. Latham wrote a letter to the Journal of Mammalogy [PDF], announcing a “Simple Method for Identification of Least Weasel.”

“It was discovered,” he wrote, “that the fur of the least weasel would fluoresce under ultra-violet light, producing a vivid lavender color. The fur of the other two species remained a dull brown … Thus, identification is positively and simply made, immediately.”

Latham’s glow-in-the-dark-weasel trick thereby entered the canon of weasel facts. Even today, you can find numerous sources claiming that least weasels glow under UV light. There’s just one problem: his method has never been validated. Nobody has ever reproduced his attempts. Still, it’s possible that Mustela nivalis glows in the dark. Given everything else we know about weasels, it wouldn’t be surprising.