During brutal Antarctic winters, temperatures can drop below -50°C and winds can howl above 180 km per hour. Emperor penguins survive in this extreme environment by forming dense huddles to protect themselves against the frigid temperatures and icy winds. Now, a team of scientists have described the wave-like pattern of movement individual penguins follow as they move throughout the huddle.
By clustering tightly together, the penguins conserve enough heat to stay alive. But birds at the periphery of the huddle are more exposed to the wind and cold than those at the core. To ensure all individuals in the huddle remain warm, the penguins must continuously change position. Birds at the exposed edges of the huddle gradually move towards the center of the huddle where they warm up before returning to the edge again in a continuous wave of movement.
A team of scientists working at Dronning Maud Land in the Antarctic recently made high-resolution video recordings of an Emperor penguin colony during a winter. Their aim was to better understand just how penguins in a huddle move to best ensure the survival of all individuals.
They found that penguins within the huddle moved in periodic waves that occurred every 30 to 60 seconds and which traveled at a speed of 12 cm every second throughout the huddle. Such movement patterns are too slow to be seen with the naked eye, but when hundreds of penguins are tracked over several hours, they become apparent.
The research team included Physicist Daniel P. Zitterbart from the University of Erlangen-Nuremberg, Germany, biophysicist Ben Fabry from Erlangen University, physiologist James P. Butler from Harvard University and marine biologist Barbara Wienecke from the Australian Antarctic Division.
Zitterbart DP, Wienecke B, Butler JP, Fabry B (2011) Coordinated Movements Prevent Jamming in an Emperor Penguin Huddle. PLoS ONE 6(6): e20260. doi:10.1371/journal.pone.0020260
Photo © Martin Ruegner / Getty Images.
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