Weasels are small but serious predators capable of eating 35% of their body weight each day

Bobcats and coyotes might be common sightings in the City of Calgary, but seeing a weasel — a small, speedy and usually nocturnal critter? That's not your everyday occurrence.

So when naturalist Brian Keating saw one of the pint-sized carnivores outside his house in Inglewood last Thursday, he was sure to snap some photos.

Keating's wife spotted the weasel across the street, popping up from a storm drain. Keating then used a mouse-in-distress call to encourage it to come closer.

"Imagine a mouse being, you know, taken out by something big and carnivorous," Keating told The Homestretch on Monday as he recreated his mouse-in-distress call, a sort of "mournful squeak."

Making noises to attract a wild animal's attention for a photo is something Keating does not encourage. He made an exception this time because they were in the city, not a wild park, and it was such an uncommon sighting.

The call worked.

"The weasel not only made an appearance, but it came towards me on the sidewalk wondering where the mouse was," said Keating. "But it quickly realized I wasn't going to produce the mouse that it was hoping for. And so it bolted down the sidewalk."

Later, the weasel returned and tried to prey on a red squirrel that took up residence in Keating's backyard a few years ago. It went away empty-pawed, though, as the cantankerous squirrel ran straight toward the predator and scared it off.

Savoury squirrels in weasel's diet

Weasels probably don't hunt the larger, introduced Eastern grey squirrel that is so common in Calgary, but the smaller red squirrel is likely in their diet, said Keating. So is the young of both species, if the weasel is able to get into the nesting den.

"Mostly these weasels are found in pastures with lots of ground squirrels and then they supplement their ground squirrel consumption by eating voles," said Keating.

Weasels are very hyper, and require a lot of food: on average 35 grams per day, which is up to 35 per cent of their body weight. Usually after small rodents, they can also take down animals five to 10 times their own weight — like hares.

Keating remembers when he worked at the Calgary Zoo and saw, from his office, a weasel cleaning out a den of half a dozen baby gophers, running past the window with one at a time.

Another time, in the winter, he saw a weasel in Saskatchewan drag a hibernating gopher out of its burrow and kill it.

"They are serious predators, and they're designed for pursuing prey down tunnels," he said.

Tenacious, with a long, thin body, weasels develop their "killing behaviour" at a young age: about eight weeks after they're born.

They live for seven or eight years, and in the winter, their summer coat is exchanged for one that is snow-white, except for a distinctive black tail tip.

You might not see a weasel in your city backyard, but if you're out on their turf, keep your eyes peeled for these elusive predators — in the winter, they look like "a puff ball of cotton blowing across the snow," said Keating.

For more fascinating stories about Alberta's wildlife from naturalist Brian Keating, visit his website and check out these stories:

• Calgary naturalist recounts memorable sighting of grizzly bear family
• Alberta has 7 species of cicada and they're among the loudest insects on the planet
• From finches to robins, it's not uncommon for birds to build their homes on your homes
• Rare black ground squirrel spotted in Banff alpine area

With files from The Homestretch.