Emperor penguins are able to maintain the tight huddle that protects them from the harsh conditions of an Antarctic winter with stop-and-go movements like cars in a traffic jam. By using a mathematical model that computes the positions, movements and interactions of individual penguins in a huddle, we show that an individual penguin needs to move by only 2 cm in any direction for its neighbour to react and to close the gap that may have formed. These movements then flow through the entire huddle like a travelling wave and play a vital role in keeping the huddle as dense as possible and protecting the penguins from the cold. The wave also helps smaller huddles merge into larger ones.
Our mathematical model resembles those used to study traffic jams. We also compare the model simulations with video recordings of a real-life penguin huddle. Unlike a traffic jam, we found that 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 develops between two penguins.
Read the full publication in the New Journal of Physics.