June 2, 2011

Coordinated Movements Help Penguins Stay Warm

The mystery of how penguins stay warm  in Antarctic winter temperatures below -50 ° C with gale-force winds has been revealed by an international team of scientists.

Time lapse video shows the birds move in almost imperceptible waves through tightly packed clusters of birds, which over time drastically change its structure, BBC News reports.

Physicist Daniel P. Zitterbart from the University of Erlangen-Nuremberg, Germany spent a recent winter making high-resolution video recordings of an Emperor penguin colony near Dronning Maud Land in the Antarctic.

Together with biophysicist Ben Fabry from Erlangen University, physiologist James P. Butler from Harvard University, and marine biologist Barbara Wienecke from the Australian Antarctic Division, it was found that penguins in a huddle move in periodic waves allowing animals from the outside to enter the tightly packed huddle and to warm up.

It is during this period that the male Emperor penguins pack tightly together not only to keep themselves warm but also to incubate their eggs while the females have headed out to sea.

Emperor penguins have long intrigued scientists. One unresolved question was how penguins move to the inside of a huddle when the animals stand so tightly that no movement seemed possible.

Lead author Daniel Zitterbart, a physicist at the University of Erlangen-Nuremberg in Germany, said: "The penguins have to huddle or otherwise they lose energy. "If the huddle is too loose - the penguins freeze. But if you huddle too tight, you can't move at all. Anywhere you want to go, there is another penguin there."

Time lapse cameras took an image of a colony every 1.3 seconds over a period of several hours, to reveal the huddle was far from a motionless mass. Dr. Zitterbart explained, "The colony would stay still for most of the time, but every 30-60 seconds one penguin or a group of penguin starts to move - just a little bit. This makes the surrounding ones move - and all of a sudden this moves throughout the colony like a wave."

This movement through the group was very subtle, it was invisible to the naked eye in real time, but over a longer period it had an impact on the colony's structure. By propelling the tightly packed penguins forward, it allowed smaller huddles to merge into larger ones.

As the wave swept to the front of the group, some penguins would waddle out of the pack and head to the back. This means that over several hours, penguins would use the waves to travel through the colony, and get a chance to share the warmth.


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