It Takes One Penguin to Break Up a Huddle

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In nature documentaries, the huddles performed by penguins are often portrayed as astonishing acts of cooperation. And while watching thousands of penguins rotate through a crowd is impressive, this behavior doesn’t always end so gracefully once the camera cuts away.

During the 2005, 2006, and 2008 breeding seasons, André Ancel of the University of Strasbourg in France and his colleagues studied about 3000 breeding pairs of the emperor penguin colony of Antarctica’s Pointe Géologie Archipelago. In the December issue of Animal Behavior, the researchers report that the huddles they observed are much more complicated than they appear. The arrangements lasted a few hours at the most, and all it took was one penguin to break up the group in less than two minutes. 

In penguin huddles, the birds in the center are always depicted as having the sweetest set-ups while it's the ones around the perimeter that are thought to be taking one for the team. But when penguins decide to give up their prime interior spot, it's not necessarily out of altruism. The heat-conserving strategy works so well that the center of a huddle can reach temperatures of nearly 100°F, which is well past the point of comfort for penguins. Penguins shift towards the outside of the group not just to give other penguins a chance to get in, but because they're looking for some relief for themselves. After leaving a huddle, Ancel and his team observed some penguins eating snow, possibly as a way to cool down.

It was for this reason that the team of researchers hypothesized that most huddle breakups would begin at the center, but they only observed this happening once. Most of the time it was started by penguins on the exterior, and within two minutes of departure the huddle would be complete broken up. The huddles lasted anywhere from a dozen minutes to several hours, but the average length was 50 minutes. After they dispersed, a haze of warm air could sometimes be seen rising over the colony. The researchers think that while huddles begin as a way to conserve heat, the sudden breakups help to dissipate it. Consider that the next time you're watching footage of a penguin huddle—you should probably save some sympathy for the guys in the middle. 

[h/t: Science News]