A World Without Koalas? Losing the Marsupial Could Make Australian Wildfires Worse
If you go strolling through one of Australia's ancient eucalyptus forests, you probably won't notice the koala perched high in the tree canopy. Its bottom, a swirl of white, gray and brown fur, blends in with the multicolored bark, creating a camouflage that's tough to beat.
But the koala knows you're there. It's observing you quietly, half-heartedly, like a jet-lagged passenger watching a boring in-flight movie. Koalas have sharp incisors and long claws and can be feisty if provoked, but they're mostly unbothered by what happens around them, says Rebecca Johnson, associate director for science and chief scientist at the Smithsonian National Museum of Natural History. Their disinterest isn't personal. It's a natural response to their main source of food and water: eucalyptus leaves.
Eucalyptus is a toxic plant. Koalas have specialized digestive systems that enable them to eat certain varieties of the poisonous tree, but it takes a lot of effort. All that energy spent eating and digesting the nutrient-poor leaves makes these understated tree-dwellers incredibly sleepy.
Every animal plays an important role in a balanced ecosystem. Koalas are no exception, though you would be forgiven for thinking otherwise, says Jennifer Tobey, a researcher with the San Diego Zoo Wildlife Alliance. "They sleep most of the time. How complex can these little guys be? I'll tell you, we keep learning new and different things all the time about them."
Koalas face extinction in New South Wales in less than 30 years. Similar projections are likely to follow in other parts of the continent. Australia is a country of extremes, grappling with rising temperatures and an increase in the frequency and severity of wildfires and droughts that are killing off eucalyptus habitats and koalas at a rapid pace.
In the devastating wildfires in Australia in 2019 and 2020, 61,000 koalas died and more than 28 million acres burned. Those fires weren't typical, but they're part of a growing trend that could become Australia's new normal.
Other threats, such as deforestation, predators, disease and roadside accidents were already making things more difficult for koalas and their habitat, driving the population down. The number of koalas has dropped by half in the past 20 years alone, prompting the Australian government in February to change koalas' conservation status from vulnerable to endangered in most of the country.
No one knows exactly what would happen if Australia's iconic marsupial went extinct, but everyone agrees on one thing: They don't ever want to find out. "Unfortunately, we tend to find things out too late, you know, once an animal like that is gone," Tobey says.
Looking to the past
The first koalas date back 20 million years, says Johnson. Over that time period, as many as 20 species of koalas existed at various points across Australia. Phascolarctos cinereus, the single koala species left today, dates back just 350,000 years.
Most of Australia's estimated 32,065 to 57,920 koalas live on the eastern and southeastern coast, as their habitat gets pushed farther and farther toward the sea. Johnson refers to their remaining territory as a "sliver" of coastline.
"Koalas have a long history of being exploited, particularly by the earliest European settlers to Australia, so they have been through a lot of population threats through hunting or through land clearing and habitat modification," Johnson says. Practices like deforestation, along with predators, disease and climate change, pose increasing threats to koalas.
It wasn't always that way. The Indigenous people who have lived in Australia for at least 50,000 years coexisted peacefully with koalas for generations, Johnson says. The word "koala" comes from the Dharug word "gula," which means "no water," referring to how the eucalyptus-dependent marsupials don't drink water.
Many indigenous cultures in Australia even incorporate koalas into their creation stories and belief systems, Johnson adds, which include a close bond with nature and respect for living things. "That is just an acknowledgement that that kind of traditional knowledge has obviously been known for a very long time and is really important to reset how we might think about [caring for koalas] in the future."
What we'd lose
If koalas go extinct, what would happen? The short answer: No one really knows, but scientists have some educated guesses.
Tobey believes the health of the eucalyptus forests would suffer without koalas. Even though koalas have no competition for eating eucalyptus, many other species live in the forests. By eating more than a pound of eucalyptus leaves every day, each koala helps control plant growth, balance the forest ecosystem and support forest life for insects and birds.
Because it takes koalas a long time to digest the toxic eucalyptus leaves, their droppings constantly replenish the nearby soil, Tobey says. On the occasion they do climb down from a tree to mate or move to another tree, they might also carry plant life with them and unknowingly assist with pollination.
Eating such large quantities of eucalyptus even helps reduce the amount of highly flammable eucalyptus available to burn during wildfire season.
"They help eat the fuel load, although with so few koalas left, it's hard to say how much they're helping that effort now," says Karen Marsh, a research fellow in the Research School of Biology at the Australian National University.
Wildfires in the regions where koalas live typically occur in spring and summer, but more fires are popping up outside the standard season. Some fires have also increased in severity, which scientists attribute at least partly to climate change and expect to continue amid changing weather patterns.
Koalas are only found in Australia. It's the sixth largest country in the world by land mass, but 20% is made up of desert, where average summer temperatures soar into the high 90s and low 100s degrees Fahrenheit. Australia has gotten 2.5 degrees hotter since 1910, 0.6 degrees more than the global average increase. The last decade has been the hottest ever recorded in the country.
More megafires, like the ones Australia experienced in 2019 and 2020, could significantly alter eucalyptus habitats, says Michael Grose, a research scientist at the Commonwealth Scientific and Industrial Research Organisation, Australia's national science agency. Some species of eucalyptus might be able to handle being burned often and rebound quickly while others might die out permanently, potentially disrupting the quality and variety of trees available to koalas.
If koalas go extinct and are no longer around to eat eucalyptus leaves, eucalyptus trees might evolve to be less toxic, says Marsh. If that happens, it could lead to population surges among various animals that realize they can now eat eucalyptus until the trees are decimated, followed by sharp population declines among those species.
Scientists also believe there's a lot to learn from koalas in terms of their gut microbiome, which has evolved to digest the poisonous eucalyptus leaves. Their "niche diet" probably has an effect on the ecosystem, although no one knows exactly how, says Johnson. "They very likely have their own parasites that they've co-evolved with, so they would all disappear [if koalas go extinct]."
Koalas are also a monotypic species, which means they're the last living species from their family tree, Johnson says. "As far as biodiversity goes, it would be a pretty substantial loss of a single branch that's been hanging on for a long time now."
Fortunately, because koalas don't travel far from their favorite tree, the single species as a whole still has a "reasonable amount of genetic diversity," Johnson adds. That diversity might help protect koalas from certain health issues where other marsupials, like the endangered Tasmanian devil and the extinct Tasmanian tiger, have not been as lucky.
Save the koalas
Koalas contribute much more than enriching nearby soil and eating flammable leaves to reduce the fuel load. They generate an estimated $3.2 billion to Australia in annual tourism revenue and account for 30,000 jobs, according to the Australian Koala Foundation.
"People come to Australia to see koalas. They're the symbol of caring for the environment and caring for biodiversity and uniqueness to Australia. So it's hard to even quantify what that means," says Johnson. They're featured on Australian tourism sites, are popular zoo headliners and were even the face of Australian airline Qantas from 1967 to 1992. Losing them would strip away a crucial piece of national identity.
Since koalas were listed as endangered in February, the Australian government has outlined conservation efforts, though some conservationists believe it is not be enough. The government has invested $50 million to restore koala habitats, assist with disease prevention and medical research and conduct an updated count of the remaining koalas in the country.
In an effort to save koalas, researchers are learning what they can from the Tasmanian devil and the Tasmanian tiger. Scientists from the University of Melbourne's Thylacine Integrated Genetic Restoration Research Lab are even working to bring Tasmanian tigers back from the dead. The biotechnology being used for that project could extend to other species in trouble, like the koala, and prevent them from going extinct.
Whatever koala protection plans are in the works Johnson urges haste, so no one has to find out exactly what will happen if koalas go extinct.
"You can't just keep on making certain decisions that impact habitat and expect nothing to happen to the animals that rely on that habitat," she says.
She's glad the Australian government is "relying on science to make decisions." But, she says, they shouldn't wait long to put their ideas into action.
"It's a really satisfying and exciting thing to see a koala in the wild," Johnson says. "To take that away would be pretty sad. That's an inadequate word to describe what it would be like to not be able to see a koala in the wild."