Koalas in crisis:
why the Aussie marsupial is under threat
Dr Valentina Mella is scanning through video footage showing fluff yeared koalas crouching over water bowls, lapping greedily. In one clip, a furry marsupial is cautiously sharing a drink with an echidna.
That might not seem remarkable, except for the fact that koalas aren’t supposed to drink. Traditionally, they take their water from the gum leaves they eat. Yet a combination of drought, climate change and fiercer El Niño weather patterns has put koalas in the Australian states of Queensland and NSW under intense stress – so much so that they are beginning to change behaviours established over millennia.
In total, Dr Mella and her fellow researchers have collected hundreds of clips of koalas drinking from specially designed water stations. That’s an enormous amount of water for an animal whose name literally means “no drink”.
“We didn’t find any babies this time,” says Italian-born Dr Mella, who is delving into the habits of the iconic tree dweller in an attempt to unlock the secrets of the koala’s long-term survival in a changing climate. “We had the hardest catch I’ve ever seen.”
Dr Mella has just returned from her latest research trip to Gunnedah, Australia’s self-proclaimed koala capital. Despite the northern NSW town’s reputation, locals have been reporting fewer sightings of the popular marsupial. “People who had koalas in their backyards for years told us, ‘I had five and now I have zero,’” Dr Mella says. “We can see every year that we go how the numbers are going down.”
Koalas have always been shy creatures, but in this part of Australia there has been a notable decline in numbers. The native animals that are most often seen clinging to tree trunks with their fearsome claws may look hardy, but they are a delicate species. They’re reliant on the eucalyptus trees that provide them with food, hydration and shelter. As Australian summer heat increases in intensity, dehydration and heat stress are taking their toll.
A heatwave that hit northern NSW eight years ago was particularly devastating for the koala population. “They were thriving until 2009 and then the decline started,” Dr Mella says.
Koalas were found dead or dying at the base of trees. Vets who tried to treat the dying animals found their kidneys were failing. Among the survivors, chlamydia rates increased. Researchers estimate up to one-quarter of the Gunnedah koala population was wiped out. In NSW, Queensland and the ACT, the koala is now listed as a threatened species.
When Dr Mella signed on as the behavioural scientist as part of a large University of Sydney koala study in Gunnedah, she met local farmer Robert Frend, who told her something was changing. “They’re not doing well,” he said. “I think it has something to do with water.”
Scientific literature is full of statements that koalas do not need water to survive because they are able to get their fluids from eucalyptus leaves. Yet the locals in Gunnedah told Dr Mella they thought koalas needed to drink.
We know they seek out water when they need it. Every summer, photos emerge of koalas drinking from bird baths, swimming pools or the family dog’s bowl. Australian Koala Foundation CEO, Deborah Tabart, says the foundation has been telling people to put water out for koalas for 20 years.
Dr Mella says, “I approached Rob and I said to him, ‘Shall we try to give them some water?’”
She is hopeful her findings could help save the lives of Australia’s most beloved native animal.
Dr Mella’s study is a world first, but when it started it wasn’t the most scientific of experiments. Rob created a rudimentary drinking station out of half a car tyre. They placed it in a tree, then sat back to wait and see if the koalas would be tempted. It was April and Dr Mella wasn’t sure the koalas would drink.
“I will never forget this – we were in the field and I saw a koala climbing up the tree to drink,” Dr Mella says.
She whipped out her phone to capture some photos. They turned out horribly, Dr Mella says, laughing, as she couldn’t keep her hand still – she was shaking from happiness.
“We thought, right, this is a goer.”
All of the funding available to the University of Sydney koala project had been allocated, so Rob made drinking stations for the koalas using scrap metal and other items he had on hand. He came up with a design to deliver water to koalas in a safe environment and rigged them up with motion-sensor cameras that are activated if an animal stops for a drink.
They set up 20 water stations, dubbed Blinky Drinkers, to monitor the drinking habits of koalas. Very quickly, they found the animals were stopping to drink for an average of 10 minutes at a time. The poor little creatures were parched.
“This tells us they do need water and it’s something that they’re not finding anywhere else,” Dr Mella says.
Throughout the autumn and winter months, koalas drank from the stations 124 times. In summer, this more than doubled to 262. “My thought was there must be such bad moisture in
those leaves that they need to drink from somewhere because otherwise I cannot explain why we would have so many koalas come to drink from our stations in cool months,” Dr Mella says.
“If the water level in the leaves they eat has decreased and it’s getting worse and worse with climate change and hotter and drier conditions, then these animals are obviously going to show behaviours that earlier were only rare.”
University of Queensland ecological researcher Dr Bill Ellis, who has been studying koalas for decades, says he has observed the marsupials die in greater numbers during summer.
“Females seemed to lose babies more often when it was really hot and dry than at other times,” he says.
“You would notice in the good years there seemed to be more joeys floating around.”
Dr Ellis has witnessed first-hand the terrible effects of heat on koalas. “Whenever we get those really hot, dry summers, we find the koalas sitting on the ground just trying to keep cool,” he says. “Poor little characters, they struggle.”
He says the increasingly long hot summers pose a double threat. When confronted with a heatwave, koalas will simply stop eating. “We find koalas that have empty tummies. They just haven’t been eating for days. And that’s their response to those 40-degree days. Their body temperature will get up to 38 degrees,” he says.
They need water to keep cool, but if there’s not enough moisture in the leaves, just the act of eating raises their body temperature. Because koalas get their water from the leaves, if they don’t eat, they don’t get enough water from their food to stay cool. “If they don’t eat, they die and if they do eat, they overheat,” Dr Ellis says.
What makes things even harder for koalas is that as the moisture content in the leaves decreases, they become more difficult to digest.
“Studies have shown that with climate change, the ratio between nutritional components in the leaves and toxic components change,” Dr Mella says. “Not only do they become more toxic, which means koalas take longer to digest them, they also become less nutritious.
“This is why climate change is so scary when you think about koalas because if it affects the tree, it affects their whole life.”
The next step for Dr Mella is to analyse the impact the additional water is having on the health of the animal. The fact that koalas drink water doesn’t tell us if it’s actually helping them through the summer.
Dr Mella has started looking at the health of the animals and hopes to get funding to microchip them so she can monitor who is drinking and if those who do are better off.
“We don’t really know whether those animals eventually survived,” she says, “but certainly, if you run out of water, you die pretty quickly.”
Scientist Dr Valentina Mella with one of her koala charges. There are believed to be fewer than 80,000 koalas left in the wild.
The research team hard at work. BELOW: Dr Mella and farmer Robert Frend with two of the water stations known as Blinky Drinkers.
ABOVE AND BELOW: The researchers compile data on Robert Frend’s property. LEFT: A koala’s paws are adapted for gripping and climbing.
Dr Mella and her team have made world-first discoveries about the koalas and water.