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Why do koalas hug trees? Researchers say it's to beat the heat

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Koalas are the original tree huggers, and researchers have discovered that's the key to keeping cool in the hot summer months.

Scientists placed radio collars on 37 koalas in southeastern Australia, and tracked them during the winter of 2009 and the summer of 2010-11 to determine what makes them cool off, the Los Angeles Times reports. They took detailed notes on which branches the koalas went to and what their posture was like, and used a portable weather station to determine the microclimate conditions. After also studying 130 koalas without collars, the researchers found that in the summer, the koalas would hug tree trunks or larger branches closer to the ground, while in the winter, they would go higher up in the tree.

Researchers used thermal imagine cameras to see that the tree trunks had lower surface temperatures than the canopies and branches. Acacia mearnsii are the coolest trees, and also where the koalas spent 29 percent of their time in the summer and just five percent in the winter. The findings were published Wednesday in the journal Biology Letters.