Travelling Wave helps Emperor Penguins Stay Warm, Researchers Find [video]
The ability of Empire Penguins to huddle-up during winter has always puzzled researchers. A latest study reveals how thousands of birds do a slow, complex dance and create the wave to stay warm.
There is no sense of privacy in the world of the Emperor Penguin. Each bird must stay huddled together to survive the unforgiving Antarctic wind. However, staying in a close group isn't as easy as it sounds as movement of a single penguin could ruin the formation.
During winter, temperature in the region can drop to as low as -50°C and winds could reach up to 200 km/h, according to a news release. Previous research has shown that penguins move every minute or so, which is why scientists are quite perplexed at the birds' ability to manage the density of the huddle despite the continuous movement.
Biologists at the University of Erlangen-Nuremberg in Germany and their colleagues used a mathematical model to study traffic jams and recreate the movements of the penguins. The team then compared the results using video footage of a penguin huddle.
Their analysis reveals that a penguin needs to move just 2 cm in any direction to start a chain reaction that sees the neighboring penguins shift their places. These small movements travel through the huddle like a wave.
These waves don't just keep the huddle warm, but also allow smaller groups of penguins to join a larger group.
But, unlike traffic jams, any penguin can set off this reaction, provided that there is sufficient gap between two birds- known as the "threshold gap."
"We were really surprised that a travelling wave can be triggered by any penguin in a huddle, rather than penguins on the outside trying to push in," said Daniel Zitterbart, from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI, co-author of the study. 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."
The threshold gap is about 2 cm, which is about twice as thick as penguin's compressible feather layer, which shows that penguins don't compromise on their body's warmth in a huddle.
Emperor penguin is the only vertebrate that breeds during the polar winter. Male emperors incubate the eggs
Why penguins move so frequently isn't clear. It could be that birds need to rotate the eggs. "It might be that the egg can get cold at the bottom and so the penguins have to rotate the egg every now and then," Richard Gerum, co-author of the study, told LiveScience."This is just a speculation."
The study is published in the journal New Journal of Physics.