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Besides kangaroos, koalas are probably the most famous animals in Australia.

And yet they still puzzle us.

Researchers found out only a few years ago why the marsupials (even if they are often called koala bears, they are not bears) always snuggle up to the trees and seem to hug them: They use the trunks as air conditioning to cool themselves off.

Because these are a few degrees colder than the ambient temperature, especially in summer.

Koalas spend most of their lives in the eucalyptus trees in eastern Australia.

Asleep.

They sleep up to 22 hours in the treetops.

The reason for this extremely lazy existence: You have to save energy.

Because the eucalyptus leaves are not only poor in nutrients, it also takes a lot of time to digest the hard fibers.

They also contain toxins that need to be broken down.

The animals eat up to half a kilo of eucalyptus leaves a day.

But what do koalas actually drink high up in the trees?

Source: Getty Images / John White Photos


For a long time we thought koalas didn't need to drink much anymore because they get most of the water they need to survive from the eucalyptus leaves.

Valentina Mella, behavioral scientist from the University of Sydney

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But Mella and her team should be taught better.

Scientists assume that the bag mammals get three quarters of their daily fluid requirements from the leaves.

In addition, compared to other mammals of about the same size, koalas lose little water through their skin and respiration.

Animals in captivity had already been seen drinking water.

But it was assumed that these were rather unusual and stress-related exceptions.

Likewise, if they drank from swimming pools or even people's hands in intense heat, drought or bushfires.

Thirsty koala climbs on bike and begs for water

A cyclist was literally "attacked" by a particularly thirsty koala for a sip of water.

Source: WELT / Christoph Hipp

But where did the animals get the last quarter of their water requirement?

To clarify this question, Valentina Mella and her colleagues at the University of Sydney asked other biologists and ecologists for help.

In the Australian states of Victoria and New South Wales, the scientists went on observation tours between 2006 and 2019 and kept an eye out for possible drinking habits of koalas.

They noticed something unusual a total of 46 times, as they write in their study in the journal "Ethology":

When it rained, the tree dwellers would lick the water running down from the trunks or thick branches.

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And that with astonishing endurance: a female drank in this way continuously for 15 minutes, a male even 34 minutes.

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"Since koalas are nocturnal and their behavior has rarely been observed during heavy rainfall, their drinking behavior has probably largely gone unnoticed and has been underestimated in the past," speculates Valentina Mella.

They preferred this way of drinking even when there was a watering hole right next to their tree.

Source: George Madani and Lachlan Hall


This means that koalas did not drink because of heat stress, but that this is their natural way of drinking water.

Valentina Mella, biologist at the University of Sydney

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The researchers want to find out in further studies whether this drinking behavior is common in all koala populations or only in a few areas.

They also want to clarify how much water the marsupials actually ingest by licking.

This article was first published in May 2020.