Emperor penguins “wear” an invisible shield of cold air that helps to prevent body heat loss, allowing the flightless birds to survive the sub-zero temps of Antarctica, a new study finds.

The report, published in the journal Biology Letters, demonstrates just how hardy the birds are.

“In most birds, plumage is able to resist the flow of heat, such that surface temperature is normally a few degrees above ambient temperature,” wrote Dominic McCafferty of the University of Glasgow and his colleagues. For emperor penguins, however, “During clear sky conditions, most outer surfaces of the body were colder than surrounding sub-zero air … In these conditions, the feather surface will paradoxically gain heat by convection from surrounding air.”

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It’s as though the penguin were in a mini natural convection oven set at low.

You can actually see the effect in the image below, which shows the different temperatures:

Zero degrees Celsius is 32 degrees Fahrenheit, so the bird is still chilly by our standards, but notably warmer than its surroundings.

You couldn’t ask for a better coat than that of the penguins too.

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“Penguin plumage provides more than 80 percent of total insulation, and is highly resistant to wind penetration,” according to the authors.

They add that the “thick, scaly skin” of penguins “affords good protection” from cooling and contact with ice. This species of penguin also has a relatively small bill in proportion to overall body size, which also helps to minimize heat loss.

When penguins stand a certain way, and gather together in a group, they further reduce heat loss.

Images: Université de Strasbourg and Centre National de la Recherche Scientifique (CNRS), Strasbourg, France