Scientists have unlocked the koala's secret of staying cool and avoiding dehydration in intense heat. They hug trees. The cuddly animals do not cling to trees just to sleep. Researchers cast new light on why they hug trees. A tree trunk is 5 degrees cooler than the air around it. Koalas spread themselves out on the cooler surfaces of large branches or the trunk. Trees can save koalas half the water would need to keep cool on a hot day.

Researchers studied the behaviour of 37 koalas to find out how they might survive global warming. The results were surprising. Koalas sat up in cool weather, hugged branches when it became warmer, and wrapped themselves around tree trunks when it got hot. They moved to trees with cooler trunks. Trees are cooler because they suck up water from the ground. The koala's cooling technique could help people survive hotter summers.