Scientists have unlocked the koala's secret of staying cool and avoiding dehydration in intense heat. They hug trees. For decades people thought the cuddly animals clung to trees to sleep. Researchers from Melbourne University have now cast new light on why they hug trees. Lead researcher Natalie Briscoe said a tree trunk is 5 degrees cooler than the air around it. Koalas use the cooler surface by spreading themselves out on large branches or by hugging the trunk. Ms Briscoe said: "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 off the Melbourne coast. She wanted to find out how koalas might survive global warming. Her conclusions regarding the cooling effects of the trees surprised her. Koalas sat upright in cooler weather, hugged branches when it became warmer, and wrapped themselves around tree trunks when it got hot. They even moved to different trees that had cooler trunks. She said trees are cooler because of the water they suck up from the ground. The koala's cooling technique could help us survive increasingly hot summers.