Climate change is threatening the survival of koalas (Phascolarctos cinereus), Australia's iconic marsupials. Rising temperatures are extending periods of drought and worsening the risk of bushfires and disease. Beyond these already well-known phenomena, researchers at the University of Sydney have observed an unusual behaviour: koalas have started coming down from trees to drink large quantities of water.

Koalas are now getting thirsty

Koalas ordinarily obtain most of the water they need from the eucalyptus leaves they feed on, and their sedentary lifestyle — they can sleep in trees for up to eighteen hours a day — allows them to conserve it. Researchers have documented a notable change in these animals' habits. In the town of Gunnedah, in south-eastern Australia, known as "the koala capital of the world", they filmed koalas coming down from trees to drink from artificial water stations, drinking for an average of more than ten minutes.

An increasingly hot climate

According to scientists, the explanation lies in the eucalyptus leaves themselves, which, due to the hotter and drier climate, are increasingly dry and therefore no longer provide koalas with the hydration they need, forcing them to seek out extra water. Previous research has also shown that koalas do not eat eucalyptus leaves whose water content is below 55–65 per cent. "The scientific literature is full of evidence that koalas don't need to drink water," commented Valentina Mella, a researcher at the University of Sydney, "but our results show that a water supplement could help them."

Koalas under threat

Koalas are classified as a vulnerable species on the IUCN Red List; over the past twenty years the population of these marsupials has declined significantly, falling by 40 per cent in some areas. According to the Australian Koala Foundation (AKF), there are between 45,000 and 90,000 individuals living in the wild. Koalas are threatened by habitat loss caused by heavy deforestation, by disease, and by heatwaves. Koalas typically cope with high temperatures by hugging trees, which allows them to lower their body temperature. These endearing animals have no strategies, however, for withstanding the intensification of extreme weather events. In 2009, the koala population of Gunnedah fell by 25 per cent as a result of a severe heatwave.

How to help koalas

Experts believe the situation can only get worse; according to a group of Australian and Dutch climate scientists, climate change would increase the likelihood of extreme temperatures tenfold. The koala study was also conducted in winter, and researchers believe that the problem they observed will worsen during the summer months. To help koalas stay hydrated and survive heatwaves, the researchers recommend installing dedicated water stations. "We hope to be able to use our findings to develop a practical plan for managing rural areas of Australia in the interest of this iconic species," concluded Valentina Mella.