Thanks to the recent deep freeze in North America, Calgary Zoo had to take extreme measures to protect its animals from the weather - including even the most naturally cold resistant, the zoo's king penguins.

This was in keeping with the zoo's guidelines to bring the penguins indoors when the temperature  reaches -25 degrees Celsius (-13 degrees Fahrenheit), zoo curator Malu Celli told the Globe and Mail. Temperatures were averaging at -28 degrees Celsius (-18.4 degrees Fahrenheit) in Calgary over the new year period.

"We just don't want to expose them to too much," Celli said. "To keep them safe, we decided to pick a limit to let them out."

King penguins are subantarctic birds, living not on the icy continent of Antarctica like their larger cousins, emperor penguins, but on the islands in more temperate waters a little farther north, preferring land free of snow and ice.

Although the penguins are built to withstand cold temperatures, it doesn't tend to dip down quite that far in the islands they inhabit in the wild.

The zoo's penguins happily waddle about out of doors most of the winter, but every year they'll need to be brought indoors for a short duration when the temperature plunges, just to be on the safe side.

And with a chick in the Calgary zoo flock who's still growing, safe is better than sorry.

"It's not necessarily that it's too cold for them. I believe that physiologically, they can withstand colder weather than what we have here, but these are not wild birds," Celli said.

"It's kind of like you can bundle up your kid, but then there's a point you're going to say, 'I know you're good, but I'd rather you stay inside now'."

The weather has since warmed up, and the penguins are back outside in the sunshine, where zoo visitors can come and say hello.