Going on a bear hunt: the search for koalas in Kosciuszko

Kosciuszko National Park is home to mainland Australia’s highest peak, ski fields and snow gums. ANU researchers have discovered it’s also hiding koalas.

In late 2016, a healthy male koala casually crossed the Snowy Mountains Highway and scurried up a nearby eucalyptus tree. A passing motorist spotted the animal and took some photos.

Excitement ensued. It was the first time a koala had been spotted in Kosciuszko National Park in more than 70 years.  

Home to and sharing its name with mainland Australia’s highest peak, Kosciuszko National Park is not known as an area where koalas live, Dr Karen Marsh says.

But haphazard sightings, either by members of the public or captured on wildlife cameras, gave reason to suspect there were koalas somewhere in the 6,900-square-kilometre park. 

Over the 2021-22 summer, Marsh and her team spent weeks searching for the marsupials and confirmed those suspicions. “I was interested in finding out whether there is a population of koalas in Kosciuszko and whether it’s playing a role in conserving koalas,” Marsh, a Research Fellow at the ANU Research School of Biology, says. 

An icon in peril 

This discovery of koalas within the national park expands the marsupial’s known population numbers and habitat at a time when both are under threat.  

In February 2022, koala populations in Queensland, New South Wales (NSW) and the Australian Capital Territory were officially listed as endangered. ANU Research Fellow Dr Kara Youngentob, based at the ANU Fenner School of Environment and Society, says many factors are putting koalas at risk.  

“People often refer to koala declines as a death by 1,000 cuts because one of the major issues is habitat loss,” she says.

“Koalas like to live in some of the same places that people do and so their habitat’s just getting more and more fragmented. More and more forests are being cleared for human development and other land uses and koalas are losing habitat.

“On top of that, they are contending with climate change, which is bringing more severe droughts and fires.” 

The heat associated with fire and drought is also hard on koala populations, as the koalas may struggle to get the nutrition they need if they eat less when they get too hot.

“That combination of losing habitat, and the habitat that’s left being less hospitable, is primarily why we find ourselves where we are with them today,” Youngentob says. 

Not all eucalypt is equal 

All of this isn’t helped by the fact koalas are notoriously fussy eaters. 

Marsh and Youngentob have spent years researching koalas, with a focus on nutrition. There’s a strong genetic component to what makes eucalypt good koala food or not, Youngentob says.

And it’s not easy for us mere humans to spot.

“You can have two trees of the same species; one can be really edible and the other hardly edible at all,” Youngentob says. “Even though it looks like the same tree to you and me, the underlying chemistry is different.”

A better understanding of what koalas will eat supports conservation efforts by identifying what trees should be planted to provide and maintain habitats in which the animals can thrive.  

“There’s a lot of people doing revegetation at the moment and a lot were even specifically targeted towards providing koala habitat,” Marsh says. “But we don’t know what they are actually replanting. Is it going to turn into koala habitat or not? They’re often planting trees they think are food, without realising that may not be the case.”  

Youngentob highlights the planting of climate-ready vegetation, designed to make forests more resilient to future climates, as an example. There’s a risk that some of the secondary compounds that deter herbivores such as koalas, may provide protections for the trees from heat and drought.  

“We need to know if we’re selecting trees for climate resilience, are we inadvertently also selecting trees that koalas can’t eat?

“These are big questions we need to answer quickly before we end up with huge areas of revegetation and carbon offsets that are only trees, not food. Because I think people really want both.” 

Research in the ashes 

Recent research on the nutritional value of koala habitat has examined areas affected by the Black Summer bushfires. In the wake of the fires, ANU became the temporary home to more than 35 displaced and injured koalas.

Once the koalas were released back into the wild in NSW’s Snowy Monaro region, PhD scholar Murraya Lane spent a year tracking 30 koalas, including some that hadn’t been in care. Early results from the study show the body condition of most of the koalas improved. 

“We wanted to see how these koalas navigated the landscape, seeing if koalas that were kept in care did better in the landscape after being released, and also compare these movements to koalas in an unburnt area,” Lane says.

“The preliminary results indicated to us that most of the koalas in the burnt landscape were surviving and doing well, utilising burnt and unburnt areas and finding sufficient food.” 

The take-home message, Youngentob says, is that with rains like we experienced after the bushfires, the landscape can recover and still be home to koalas.

“We shouldn’t write it off. Sometimes salvage logging happens in forests after fire because people think it’s destroyed and the animals can’t live there, but the ones that survived the fire can survive in that habitat.”   

As part of the post-fire studies, Lane used a giant slingshot to collect leaf samples from burnt and unburnt forest to examine how the nutritional quality of the habitat changes over time after a fire, compared to an area that didn’t burn.

“Fires are obviously a major part of our Australian landscape and can have a range of negative effects on our flora and fauna, however we actually know very little about the effects of fire on eucalypt nutrition and the nutritional and chemical composition of the new growth that is produced by eucalypts after fire,” Lane says.

“Understanding whether koalas can eat epicormic growth will be really important going forward as it shows us that they may be able to survive and persist in a burnt landscape, as this growth is the first to be produced after a fire event.” 

Hiding in the hills 

Expanding our knowledge of koala habitat was one of the motivations behind the hunt for koalas in the remote and rugged terrain of Kosciuszko National Park, southwest of Canberra. 

The wet summer made some locations inaccessible, but Marsh and her team spent weeks in the park peering up into canopies, inspecting claw marks on tree trunks, and examining animal scats.

The researchers used acoustic recorders, placed at about 90 sites throughout the park, in the hope of capturing bellowing calls from male koalas during the breeding season, which is usually over spring and summer.  

Analysis of the recordings revealed male koalas at 14 sites spread across about 250 square kilometres in the southeast of the park. The recordings don’t distinguish between individuals, so researchers don’t know how many koalas were found at this stage.  

“We thought they were probably there, but it was so exciting when we got the first confirmation of koala bellows on the acoustic recorders,” Marsh says. “It’s nice to know that there are koalas out there that we don’t know about simply because we haven’t looked in those locations before.” 

Most of the sites where koalas were recorded were more than 1,000 metres above sea level.

“This is significant because most other known populations of koalas are found at lower elevations,” Marsh says. “The sites in Kosciuszko National Park are likely to be less impacted by rising temperatures under climate change than some of the other areas in Australia where koalas live.” 

Finding koalas in the park will help refine understanding of koala habitat and what eucalypt species and forest communities can support koalas in our region.

“Most of our understanding in New South Wales comes from populations that are much further north, but we have a completely different suite of eucalypt species down here, so it’s difficult to use the northern information to tell us which areas are most valuable to koalas in southern New South Wales,” Marsh says. 

The discovery shows our most beloved creature can still surprise us and that it’s important to keep an open mind about where koalas might be, Youngentob says.

“Despite them being such an iconic animal in Australia, we still have more to learn.”