Penguins in huddles move like stop-and-go traffic to resist cold BREMERHAVEN, Germany, Dec. 17 (UPI) -- Emperor penguins maintain the tight huddle that protects them from the Antarctic winter by moving the way cars do in a traffic jam, a German study said. In the dense huddle meant to protect them from the harsh conditions, an individual penguin only needs to move three-quarters of an inch in any direction for its neighbor to react and also perform a step to stay close to it, researchers at the Helmholtz Centre for Polar and Marine Research at the Alfred Wegener Institute reported Monday. The tiny movements flow through the entire huddle like a traveling wave and play a vital role in keeping the huddle as dense as possible to protect the penguins from the cold, the researchers said. A previous study showed penguins in a huddle move every 30 to 60 seconds, causing surrounding penguins to move with them. "Our previous study showed how penguins use travelling waves to allow movement in a densely packed huddle, but we had no explanation as to how these waves propagate and how they are triggered," researcher Daniel Zitterbart said in a release from the Institute of Physics in London.. The researchers used a mathematical model previously used to study traffic jams and compared the results with an analysis of video recordings of a real-life penguin huddle. The waves of movements in a penguin huddle can originate from any single penguin and can propagate in any direction as soon as a sufficient gap, known as a "threshold distance," develops between two penguins, they found. "We were really surprised that a traveling wave can be triggered by any penguin in a huddle, rather than penguins on the outside trying to push in," Zitterbart said. We also found it amazing how two waves, if triggered shortly after each other, merged instead of passing one another, making sure the huddle remains compact.