• It is believed that koalas get most of the water they consume from the leaves
  • Researchers of a new study found that koalas drink water by licking rain from tree trunks
  • Koalas may be more reliant on free water than previously believed

For the first time, researchers observed the drinking behavior of koalas in the wild. Their observations suggest that koalas may be more reliant on water than previously thought.

It is believed that wild koalas get about three-quarters of their water needs from the fresh eucalyptus leaves that they consume every day. Although koalas have been observed to drink water, whether in captivity, during droughts, or after fires, this behavior is considered unusual and has even been linked to severe heat stress or disease.

How wild koalas actually access water from the treetops has remained a mystery but, a new study published in Ethology now details koalas' drinking behavior in the wild for the first time.

According to the study, wild koalas actually drink by licking the water running down tree trunks.

For the study, the researchers collected observations of koalas drinking water in the wild, both from citizen scientists as well as ecologists. There were 44 observations of koalas licking the water running down a tree trunk during or right after rain in the You Yangs Regional Park while two other such observations were made between Gunnedah and Mullaley. In fact, in one of them, an adult male koala drank rainwater for 34 minutes.

The licking behavior was observed during a variety of weather conditions, including when water was available in dams.

"For a long time, we thought koalas didn't need to drink much at all because they gained the majority of the water they need to survive in the gum leaves they feed on. But now we have observed them licking water from tree trunks," study co-author Dr. Valentina Mella said in a news release from The University of Sydney that was published on Sunday (May 3), which also happens to be Wild Koala Day. "This significantly alters our understanding of how koalas gain water in the wild. It is very exciting."

Dr. Mella further explained that such behaviors were likely not observed before because koalas are nocturnal animals and observations are rarely done during heavy rainfall. As such, the researchers note that koalas may actually be more reliant on free water than previously thought.

"This suggests koalas were drinking not as a result of heat stress and that this behaviour is likely to represent how koalas naturally access water," Dr. Mella said.

That said, Australia is now experiencing a long dry period, with record maximum temperatures and "severe" rain deficits. This could have serious consequences for koalas as well as the other creatures that may experience severe heat stress.

"This type of drinking behaviour — licking tree trunks — relies on koalas being able to experience regular rainfall to access free water and indicates that they may suffer serious detrimental effects if lack of rain compromises their ability to access free water," Dr. Mella said, also noting the importance of retaining trees to conserve the species.

Apart from drought and the effects of climate change, the Australian government notes disease, urban expansion, predation by dogs, habitat loss, and vehicle strikes as threats to koalas.

Koala bears are native to Australia. ibt