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Lead researcher Dr Mella on on the farm where the study is being carried out. Credit Caroline Marschner.
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Koalas driven to drink by climate change

3 March 2017
Koalas were thought mostly to eat and sleep, not drink

Leaves were thought to be all koalas needed but video footage shows koalas are thirsty; it is believed climate change is transforming the national icon's behavior, adding to stresses from heatwaves, tree-felling and disease.

It's believed koalas are particularly vulnerable to climate change because they rely exclusively on trees.
Dr Valentina Mella

Video surveillance

Researchers of this unique study were surprised to find koalas were very thirsty, drinking at the artificial water stations day and night for an average of more than 10 minutes – and this was in autumn-winter.

A regular visitor to a neighbouring farm’s bird bath on The Dip property in Gunnedah disappeared after a recent heatwave. Credit Kate Wilson. Top of page: Lead researcher Dr Mella on on the farm where the study is being carried out. Credit Caroline Marschner.

A regular visitor to a neighbouring farm disappeared after a recent heatwave. Credit: Kate Wilson. Top of page: Dr Valentina Mella on the farm where the study is being carried out. Credit: Caroline Marschner.

The dry Australian climate is thought to be ideal for the native tree-borne animal, the koala – believed only to need leaves for its nourishment and seldom drink water – but University of Sydney researchers are concerned climate change is driving the national icon to change its behaviour, as shown by new video surveillance.

Monitored during winter, the vulnerable species in the proclaimed Koala Capital of the World in Gunnedah were found to be very thirsty, drinking from the artificial water stations day and night, for an average of more than 10 minutes.

Conservation biologists and veterinarians from the University of Sydney, who designed and analysed the remote surveilance, expect the results being compiled from summer will be even more extreme.

The koalas not only drank in the tree tops but even left the safety of their homes to seek the water drinkers on ground during the day, when they would normally be asleep. 

Dr Valentina Mella, a postdoctoral researcher in the University’s School of Life and Environmental Sciences, said: “What will happen when temperatures rise in summer to make the leaves even drier and the koalas require more relief?”

“This is the first study to document the role of water and the possible benefit of water supplementation for koala populations,” Dr Mella said.

To help researchers set up the long-term study, which started last year, farmer Robert Frend designed the water stations, which he called Blinky Drinkers. Although Gunnedah was the only town to experience an increase in its koala population in New South Wales just over a decade ago after a series of tree-planting campaigns, its population was later slashed by 25 percent during a heat wave in 2009.

“Increasing hot and dry conditions will mean more droughts and heat waves affecting the koalas’ habitat,” Dr Mella said.

“It is believed that koalas are particularly vulnerable to climate change because they rely exclusively on trees – not only to sleep on but also for eating, which together comprise of the bulk of their activities.”

Koalas are listed as vulnerable in both national and state legislations because of drastic population declines and local extinctions.

Dr Mella said koalas’ vulnerable status had been largely attributed to loss and fragmentation of habitat, disease, dog attacks and collisions with vehicles.

Her research investigating the role of climate change follows on from previous studies that have shown the gum leaves koalas eat could dry out, with koalas rejecting the foliage when leaves had a water content of less than a juicy 55-65 percent.

“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.

“This is a perfect example of how the understanding of animal behaviour can be applied to solve pressing problems.

“We hope to use our findings to create a practical plan to manage Australia's rural lands for this iconic species.”


Vivienne Reiner

Media and PR Adviser (Science, Veterinary Science, Agriculture)
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