Tree-Hugging Koalas Keep Their Cool

In extreme heat, koalas press themselves against tree trunks, which can be 9 degrees cooler than the air.

Koalas grab onto tree trunks to stay cool in extreme heat, a new study says, offering new insight into how best to preserve sensitive animal habitats.

Koalas grab onto tree trunks to stay cool in extreme heat, a new study says, offering insight into how best to preserve sensitive animal habitats.

By + More

Australia’s furry tree-huggers may be onto something.

Koalas latch onto cooler tree trunks to cope with extreme heat, new research has found, shedding light on how to protect sensitive habitats for koalas and other animals that may use trees as natural air conditioners.

"Access to cool tree trunks would significantly reduce the amount of heat stress for koalas," Michael Kearney, one of the study’s co-authors, said in a statement, effectively confirming “our idea that 'tree hugging' was an important cooling behavior in extreme heat."

[EPA: Global Warming Here and Now]

Researchers used thermal imaging and watched 30 koalas during a hot spell on French Island in Victoria, located in southeast Australia. The images showed that the animals chose to hug trees that were cooler than the air by as much as 9 degrees or more.

"These findings underscore the importance of trees to koalas especially in the context of climate extremes," Kearney said. “In this study the coolest trees were acacias. They're not a koala food tree, but clearly they can be important when it comes to coping with the heat."

Koalas also can lick their fur or simply pant to cool off, but that can lead to dehydration. Grabbing onto a tree trunk, by contrast, can save as much as half the water a koala would otherwise use to keep cool on a hot day.

Other animals may use the same strategy.

[STUDY: 12,000-Year-Old Teen Sheds Light on First Americans]

“Cool tree trunks are likely to be an important microhabitat during hot weather for other tree-dwelling species, including primates, leopards, birds and invertebrates,” Kearney said. "The availability of cooler trees should be considered when assessing habitat suitability under current and future climate scenarios."

The study was published Wednesday in the journal Biology Letters.