Driving in a traffic jam is infuriating for most of us, but for emperor penguins braving Antarctic winters, the stop-and-go movement can be a lifesaver.
Daniel Zitterbart, a physicist with the Alfred-Wegener Institute in Germany, and a team filmed two 1,500-penguin colonies in Antarctica, one at Pointe Geologie and one at Atka Bay. They then used the videos to make mathematical models of the way the penguins moved when collected in a huddle. (Watch a video of the penguins moving in their huddle.)
Male emperor penguins spend winters packed into tight bunches that move with such fluidity some have described them as a super organism. Each male in the bunch is guarding a single egg while his mate makes a long trek across the ice to find food.
Zitterbart’s models showed that movement progresses through the huddles in waves, which any one penguin can initiate by taking a tiny step. The next penguin reacts and so on, much like cars packed onto a highway. (Watch a simulation of how the penguins move.)
“It’s hopping and stalling, and it’s moving a bit and then standing back,” Zitterbart said. “Actually what you can compare this to perfectly is a traffic jam.”
Male emperor penguins huddle together to stay warm in the winter, moving about like they're in a traffic jam. (Daniel Zitterbart)
Standing — and moving — together is key to the penguins’ ability to keep warm. The penguins position themselves just two centimeters apart, exactly double the width of one feather.
“They stand as tight as possible but not so tight that their feathers get compressed and they lose their own insulation,” Zitterbart told weather.com.
“If one penguin moves farther than this two-centimeter threshold distance, then he starts one of these traveling waves and the whole huddle moves a bit and compacts itself again.” (Watch a time-lapse video of waves moving through the huddle.)
The aim of the movement is to keep the huddle as tight as possible, to guard against the winds and the cold, which can reach minus 58 degrees Fahrenheit. In particularly bad wind or cold, multiple huddles will merge together, and their incremental method of movement allows the broods to reach each other without sacrificing warmth.
The research has been published in the New Journal of Physics.
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