Scientists discover koalas quench their thirst by licking trees

New research from a team of Australian scientists is shedding some light on the mystery of koala hydration. The study presents the first description of a previously unknown drinking behavior, showing the unique marsupials drinking by licking tree trunks during rain storms.

It has traditionally been thought the vast majority of a koala’s water needs came from the liquid content in fresh eucalyptus leaves. The animals eat over half a pound of the fresh leaves every day, but this only really covers around 75 percent of their hydration.

In captivity, or in extreme heat-wave events, koalas have been anecdotally observed to come down from trees and seek out water sources. But these behaviors are considered relatively rare, and never explained how the marsupials generally supplemented their water intake.

The new study collects 44 observations, gathered over a decade, establishing a novel drinking behavior never chronicled until now. The research suggests the animals regularly hydrate by licking water running down smooth tree trunks during times of rain.

Adult male koala licking water from a tree

“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,” explains Valentina Mella, lead on the study from the University of Sydney. “But now we have observed them licking water from tree trunks. This significantly alters our understanding of how koalas gain water in the wild. It is very exciting.”

The observations recorded in the study span a number of different seasons and weather conditions. Mella suggests the data verifies this behavior as a natural activity, unlike some more anomalous drinking behaviors observed during times of stress or drought.

“As koalas are nocturnal animals and observation of their behavior rarely occurs during heavy rainfall, it is likely that their drinking behavior has gone largely unnoticed and has therefore been underestimated in the past,” says Mella. “This suggests koalas were drinking not as a result of heat stress and that this behavior is likely to represent how koalas naturally access water.”

As well as helping answer a longstanding mystery surrounding how koalas effectively stay hydrated, the research hopes to aide ongoing conservation efforts to protect the species. With Australia’s rapidly warming climate it is suggested the animals may need supplementation to their water supply in situations of drought or low rainfall.

The new study was published in the journal Ethology.

Source: University of Sydney

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