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Side dominance in Magellanic penguins

Tuesday, July 23, 2019 - 09:45

Photo by Oliver Geiseler/BIA/Minden Pictures

Original story by Sarah Keartes at Hakai Magazine

If you ever find yourself in fisticuffs with a Magellanic penguin, you’ll want to block right. A recent study found that during fights, the pluckiest penguins in Argentina’s Punta Tombo colony were lefties. The finding is the first evidence of side dominance—also known as lateralization—in a wild population of flightless birds.

A team of researchers led by Thaís Stor, a graduate student at Brazil’s Federal University of Pernambuco, used a number of tests to see if their tuxedoed subjects had a dominant side. They looked for signs of footedness by watching when the birds stepped onto an obstacle or stretched a leg to cool off. They also looked for uneven wear on the flipper feathers as a sign of a bird’s preference for turning one way underwater, which would indicate “flipperedness.”

“The penguins show evidence of having a dominant flipper,” explains Ginger Rebstock, a researcher at the University of Washington and coauthor of the paper, adding that about half preferred turning left and half preferred turning right. Foot tests produced a similarly split result, but something interesting happened when the birds got rowdy.

Penguin fights tend to occur out of sight in deep burrows, but lasting facial injuries leave clues about each exchange. During aggressive encounters, around 70 percent of penguins showed lefty tendencies, bloodying the right side of an opponent. “They hit, they bite, they peck,” explains Rebstock, who has personal experience with such encounters. “These penguins can do some damage. I’ve been whacked. It hurts!”

That penguins have a seek-and-destroy side preference was of particular interest to the team. Side dominance happens when the brain assigns specific tasks to different hemispheres—an ability long thought to be exclusive to humans. “We’re finding, however, that pretty much every animal we study shows some sort of handedness,” says Rebstock.

Read the full article by Sarah Keartes at Hakai Magazine

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