Scientists have unlocked one of the secrets as to how koalas stay cool and avoid dehydration in the intense heat of Australian summers. They hug trees. For decades people thought the cuddly marsupials clung to trees simply because they were tired and wanted somewhere to nap. Researchers from Melbourne University have now cast new light on the tree-hugging habits of the koala. Lead researcher Natalie Briscoe said there is a five-degree difference in temperature between a tree trunk and the air. Koalas utilize the cooler surface by spreading themselves out on large branches or by hugging the trunk. Ms Briscoe said: "Access to these trees can save about half the water a koala would need to keep cool on a hot day."

Briscoe studied the behaviour of 37 koalas on an island off the Melbourne coast. She is part of a team trying to identify how koalas might survive higher temperatures brought by global warming. Her observations and conclusions regarding the cooling effects of the trees came as a surprise to her. She noted that the koalas sat upright in cooler weather, hugged branches when it became warmer, and then wrapped themselves around the tree trunk when it got hot. The animals even moved to different trees that had cooler trunks. She said the trees are probably cooler because of the water they suck up from the ground. The koala's cooling technique could be one way for humans to survive increasingly hot summers.

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