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Why geese legs don't freeze and other fascinating facts of how Alberta wildlife survives the polar vortex

Some birds enter a nightly hibernation, others have a specially designed pouch in their throat that they pack full of seeds before they retire for a cold night. These are just some of the things that help Alberta's creatures survive the deep freeze.

Despite the extreme temperatures, these critters are able to tolerate it

There are only three options for Alberta creatures during extreme weather conditions and that is to either migrate, hibernate or tolerate. (Ian Black/CBC)

It looks like this brutally cold polar vortex is hanging around Alberta until the end of the week, which means many of us will be hibernating in the safety of our heated homes.

But, most of the province's animals don't have that luxury and spend their time outside bracing against the bone chilling weather.

Brian Keating, a naturalist, spoke with The Homestretch to explain how Alberta's birds and other animals manage to survive during a cold snap.

This interview has been edited for clarity and length. 


Question: How can a tiny bird like a chickadee that hardly weighs as much as a quarter survive a week of weather like this?

A: For Canadian creatures to survive the winter they can either leave, or they can hibernate or they can tolerate. Chickadees obviously fit into the tolerate category and they do it by pure winter adaptation.

They eat as much as they can before nightfall. They'll often sleep together — especially on the colder nights — and they'll huddle in a pre-selected winter roost, like an empty bird box.

On the coldest nights, they'll actually enter into a nightly hypothermia, so they let their body temperature drop.

A wild horse pictured in the winter. (Submitted by Grady Norris)

Q: What about other birds? Any other examples of how they survive in the cold?

A:  Other birds like redpolls are Arctic birds and they come down here to our more moderate climate in this part of Alberta. But they can survive up to 20 hours without access to food.

So if it gets really cold, they can survive 20 hours in temperatures as cold as –54 C.

They've also got a specially designed pouch in their throat that they pack full of seeds before they retire for a cold night. Over that 20-hour period, they'll digest those seeds slowly.

And if it really gets cold, they'll dive into the snow to wait out heavy storms.

A rabbit in the snow. Keating says most mammals just tolerate the frigid weather. (Submitted by Grady Norris)

Q: What about the geese and ducks with their naked feet and legs? How do they stand on ice and not freeze them off?

A: They've got a countercurrent blood system in their legs, so they've got the hot arterial blood that's coming from their heart and being pushed out.

Basically, it's a heat exchanger. The hot internal blood warms up the colder blood coming in from the cold legs.

And that's the way penguins do it, too, with their little feet standing on icebergs.

Q: What about mammals? What's their secret?

A: Some hibernate like bears and marmots and ground squirrels. But most mammals just tolerate it.

Basically there's two kinds of body attributes that apply: The size of the animal and the foot loading.

Larger animals like moose they've got the long legs, so they're adapted to move easily through that deeper snow. Wolves to a degree, can stay on top of the snow or at least deal with deeper snow. 

On the most bitter of cold nights, chickadees seek shelter in nooks and crannies beneath the snow. (Rick Bremness/CBC)

But as a snow pack thickens, the foot loading becomes a big factor. For deer, it's like they're wearing stiletto high heels with those thin little legs, so their hooves puncture through the hardest snow.

There's a biological law in nature that the further north you go, the bigger the animal.

That allows the surface area compared to the body mass to diminish, so there's less heat loss per mass of the animal.

Q: How do they get food?

A: Some birds are smart. Gray jays actually glue food when it's abundant. They've got a very thick saliva, and they will hide bits of food here and there and then they'll consume it later on in the winter.

Some mammals hibernate during the winter, like bears, marmots and ground squirrels, but most simply tolerate the weather. (Submitted by Brittany Christina)

Some animals stash food. I watched a coyote a couple of years ago steal my fat feeder in my backyard. I followed him and watched him bury it.

The coyote would have enjoyed feeding on that later on if I hadn't stolen my feeder back. And so that's the way they do it.


With files from The Homestretch.

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