Koalas Are Suddenly Behaving Strangely. Why?
Australian koalas are drinking much more water than they used to—and it’s likely because of hot, dry weather aggravated by climate change.
Koalas, which normally spend most of their time in the safety of eucalyptus trees, have begun to climb down and drink from artificial water stations provided by University of Sydney researchers. The koalas of Gunnedah, a town in southeastern Australia often referred to as the “Koala Capital of the World,” were drinking from the stations for more than 10 minutes on average, according to a press release from the university.
Koalas are leaving their trees even when they would normally be asleep, according to university researchers. The animals can sleep up to 18 hours a day in trees, and their primary diet consists of eucalyptus leaves, which they often eat at night. They can eat up to two and a half pounds of leaves per day.
Researchers think the koalas’ newfound thirst is because the leaves that used to keep them hydrated are drying out as Gunnedah gets hotter and drier. The leaves used to provide enough water for the koalas that they didn’t need to drink in addition. In fact, prior research suggests that koalas reject leaves with water contents less than 55 to 65 percent.
“Increasing hot and dry conditions will mean more droughts and heat waves affecting the koalas’ habitat,” Valentina Mella, a University of Sydney postdoctoral researcher, said in a statement. “The scientific literature is filled with statements saying that koalas do not need to drink free water, but our results show that koalas could benefit from water supplementation.”
Koalas are listed as a vulnerable species by the International Union for Conservation of Nature, threatened by stressors such as heat waves, tree-felling, and disease. The koala population took a major hit during the 1920s and 1930s, when they were widely hunted. Reintroduction efforts have helped, but koalas need around a hundred trees per animal, and the amount of available Australian woodlands is shrinking.
Gunnedah has seen an increase in its koala population, but the town’s koala population dropped by 25 percent in 2009 because of a heat wave. Heat is likely to harm the area's koalas further. The study was conducted in the winter, and researchers believe the problem they observed will get worse during hotter summer months.
Australia's most recent summer (December 2016 to February 2017) brought record-breaking heat across much of New South Wales, the province that contains Gunnedah. Australian and Dutch climate scientists recently showed that climate change makes these kinds of extreme temperatures at least 10 times likelier than they otherwise would be.
But with the help of artificial water stations, Mella thinks that conservationists could give koalas a better chance to thrive.
“We hope to use our findings to create a practical plan to manage Australia's rural lands for this iconic species,” she said.
Michael Greshko contributed reporting.