Emperor penguins have a unique way to ensure not one of them gets left out in the cold as they brave the Antarctic winter.

Scientists recently discovered that the birds form tightly-packed “huddles” to keep warm and survive gale-force winds and temperatures lower than minus 50˚C.

Now researchers have learned how the penguins, which huddle together in their thousands, look after their neighbours.

Every 30 to 60 seconds, all the penguins make coordinated small steps that travel as a wave through the entire huddle.

The movements are too small to see with the naked eye, but over time they lead to large-scale re-organisation of the whole colony. This allows outlying birds to move inside the huddle and warm up.

The effect is similar to what occurs when dough is kneaded.

Dr Daniel Zitterbart, from the University of Erlangen-Nuremberg, Germany, and colleagues wrote in the online journal Public Library of Science ONE: “Penguins in a huddle are packed so tightly that individual movements become impossible.”