Penguins are renowned for being hardy animals, but a recent cold snap in North America has forced one Canadian zoo to move its king penguins inside.

Malu Celli, a curator at Calgary Zoo, said the animals had been moved from their outdoor enclosure for several days during cold weather which has seen temperatures in the region plummet to an average of -28 degrees Celsius. With the wind chill, this feels like -40 C.

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

Calgary Zoo hosts a number of penguin species, amounting to 51 individual animals in total. While king penguins are found in subantarctic regions at the northern reaches of Antarctica, as well as Tierra del Fuego, the Falkland Islands, they are not used to coping with the temperatures experienced by their relatives, the emperor penguin, which breeds during the harsh winter spent in deepest Antarctica.

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

If left to their own devices, the penguins would happily venture outside, according to Celli, but the zoo did not want to take any chances, especially with a young chick in the flock.