Koalas lick tree trunks to quench their thirst when it rains, scientists have just learned. This upsets what biologists have long thought of koalas: that they get almost all the water they need from the eucalyptus leaves they eat.
But koalas probably cover water like many animals – except they do it from trees, according to results published today in the newspaper Ethology. With fires, heat waves and droughts putting more and more stress on critters, scientists have paid close attention to how koalas stay hydrated.
“It dramatically changes our understanding of how koalas gain water in the wild. It’s very exciting, “lead author of Ethology paper and University of Sydney researcher Valentina Mella said in a statement.
The surprising discovery was made by calling on scientific citizens and independent ecologists who had observed the behavior of koalas in the wild between 2006 and 2019. A koala was caught pumping rainwater for more than 30 minutes, at a “steady pace” of two licks per second. In total, they documented 46 cases of koalas drinking from trees during and after the rain. Koalas were recorded drinking each time observations were made in the rain. According to Mella, one of the reasons why scientists hadn’t noticed it before is that people are less likely to go out and get them in bad weather. Marsupials seem to prefer smooth parts of trees where it is easier to collect flowing water.
Koalas are considered vulnerable by the International Union for Conservation of Nature, which monitors endangered species. They were devastated by massive bush fires that swept across Australia late last year. Almost a third of all koalas are said to have been destroyed in the state of New South Wales, which was the worst hit by the fires.
The same hot, dry conditions that fueled the flames left the koalas parched. Photos and videos of koalas approaching people for drinking went viral as wildfires raged across Australia last year.
Even before the last fires, Mella’s previous research have found that climate change is leaving koalas thirsty. In 2017, koalas were photographed get up to drink at artificial water stations set up by researchers – a behavior very unusual for animals which spend most of their lives in eucalyptus trees.
At the time, Mella and her colleagues thought that the behavior was due to the fact that the warmer temperatures and changes in rainfall regime dry the leaves that koalas eat. Now, she and her co-authors of the new document believe that less precipitation could be another more direct factor, leaving koalas with less rainwater to escape from the tree trunks they call home.
Mella is currently Fund raising to continue his research and set up more drinking stations for koalas. She hopes that the drink stations, which are placed in the trees, will give koalas a safe way to cool even if the world around them continues to heat up.