Australia’s apocalyptic bushfires earlier this year weren’t just unprecedented in their scale and ferocity—they weren’t even supposed to be possible yet. Over the past 20 years, the average percentage of Australia’s “temperate broadleaf and mixed” forests—lots of eucalyptus, basically—that burned each year was 1 percent. During the 2019-2020 fire season, that figure was 21 percent, the kind of catastrophe that models didn’t predict climate change could spawn until the next century.
Scientists could only watch in horror as walls of flame virtually obliterated whole ecosystems. Now, they’re beginning to take stock of which wildlife species—so many of them native only to Australia—the continent may have lost. Writing today in the journal Nature Ecology and Evolution, two dozen researchers drop some startling initial numbers about the toll.
Using government data from satellites and on-the-ground reporting, they calculate that between July 2019 and February 2020, the bushfires burned 97,000 square kilometers, or 37,500 square miles, across southern and eastern Australia. That’s an area bigger than Portugal, and a conflagration 50 times bigger than California’s largest recorded wildfire. Unfortunately, all that Australian terra is also habitat for 832 species of native vertebrate animals (those with backbones, as opposed to invertebrates like insects and spiders). Of these species, 70 had more than 30 percent of their habitat burned, and 21 of these were already listed by the Australian government as threatened with extinction.
These include iconic Australian species like koalas, kangaroos, and wallabies, and lesser-known species like the Kangaroo Island dunnart, a mouse-like marsupial that was already listed as endangered, then lost over 80 percent of its habitat to the bushfires. And these are just the vertebrates—untold numbers of invertebrates burned too. “It’s important to remember that many of the animals impacted by these fires were already declining in numbers because of habitat destruction, drought, disease, and invasive species,” says University of Queensland conservation ecologist Michelle Ward, lead author of the study. “These fires are just another nail in the coffin for many of our native species.”
The irony is that many species native to Australia are highly adapted to fire, or even dependent on it, as Australia is at its core a continent of flames. It’s perfectly natural, and indeed beneficial, for a bushfire to eat through a landscape now and then. It’s a reset button of sorts, clearing dead vegetation to allow the growth of new plants like the alpine ash eucalyptus, whose seeds only germinate on bare ground.
“But if fires reoccur too frequently, it does not allow trees to mature and produce the seed. Also, if fires are too intense, it can destroy the seeds on the ground,” says Ward. “While fire is common in large parts of the Australian landscape, the fire regime is changing. They are becoming hotter, more frequent, occurring earlier in the season, and covering larger areas with a consistent intensity. These changes seem to be occurring too fast for our native plants and animals to adapt and survive.”
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These supercharged bushfires are burning so intensely and advancing so quickly that mammals and other quick-footed fauna can no longer escape. Small critters like the marsupial antechinus that take shelter underground and in logs to ride out milder, periodic bushfires are incinerated by these bigger blazes. Even birds aren’t safe, as they get disoriented by smoke and high winds, eventually succumbing to the flames; the study found that the pilotbird lost more than 30 percent of its habitat, warranting an assessment if it should now be listed as a threatened species, the authors say.