Cats are scientifically, objectively, monumentally terrible for the planet. In the US alone, free-ranging domestic cats kill up to 3.7 billion birds and 20.7 billion mammals a year, to say nothing of reptiles and amphibians. They are a scourge of the highest order.
Now felines are poised to exacerbate the ecological crisis unfolding in Australia as an unprecedented fire season rips across the continent. Scientists have previously shown that feral cats hunt surviving animals across recently burned lands in Australia, exploiting many of the victims’ injured or weakened state. One study found that a feral cat journeyed 19 miles to a burn scar. Roaming cats might stay away for up to 50 days, massacring helpless locals on a now barren landscape. (They’re likely using a combination of sight and smell to pinpoint bushfires by their smoke.)
In another study, researchers attached collar cameras to 13 feral cats and recorded 101 hunting events in an Australian savanna, of which 32 were successful. All told, the kill rate was equivalent to 7.2 victims per cat every 24 hours, and the hunters didn’t even eat their kills a quarter of the time—they’re what are known as surplus killers. The cats were particularly successful when hunting in open areas roughly analogous to a fire-torched landscape, with successful kills 70 percent of the time. Yet another study found feral cats are highly attracted to areas that burned recently and tend to avoid ones three months or older, perhaps because vegetation has begun to grow back by that time, or they’ve simply obliterated the prey species there.
Australia is lousy with cats, as the invasive felines have established themselves in all but .2 percent of the country, according to one estimate. At their most plentiful, 100 cats may pack into a square kilometer. Because no cat is native to Australia, native species aren’t adapted to avoid and escape them. Accordingly, the Australian government has launched a large-scale feline eradication effort to try to save the natives from destruction.
At the same time, the continent has become a dramatic stage for the ravages of climate change. A hotter world means drier vegetation and bigger fires, and this season’s fires are behaving in astonishing ways: Instead of a mild bushfire burning here and there, now the conflagrations are leveling entire ecosystems. Species used to be able to escape to, say, a neighboring rainforest, but now Australia is so dry that even rainforests burn straight through. Millions upon millions of acres have burned in the past few months, and the fire season is nowhere near done.
The severity of this year’s fires is unparalleled, says conservation biologist Sarah Legge, who studies the impacts of feral cats after bushfires. “In terms of the potential for recovery, that's something that worries us a lot.”
Some areas in Australia that typically burn once every 50 to 100 years have burned three or four times in the last two decades. “They haven't had a long enough time to recover before they get smashed by another fire,” says Australian National University ecologist David Lindenmayer. “And that means that there's a very high inherent risk of the system collapsing into a different kind of environment.”
With the massive fires of the past few months, scientists won’t know the full extent of the damage until they can get in there and do surveys. What they do know is that animals face several stressors after any bushfire. Their prey may have perished or fled, and herbivores have had their vegetation wiped out. Not helping matters is the fact that Australia is withering under a brutal drought, so wildlife is already suffering a lack of water.
Feral cats aren’t the only opportunists to seek out wildfire-blighted places: Hawks and other natural predators also seize the chance to simplify their hunt. (Some particularly clever birds of prey even start fires by picking up and dropping burning sticks, thus flushing out their victims.) Legge and her colleagues have found that predation risk skyrockets twentyfold in the aftermath of a bushfire, from both natural and feral predators. With these more intense fires virtually clearing out whole landscapes, prey will find even fewer places to hide.
Cats are such effective hunters in part because they’re devilishly smart, says University of Tasmania ecologist Hugh McGregor, who studies the impacts of the feral predators. A native predator like a dingo might wander into a burn scar and hunt, then wander away. But not cats. “They're waiting and watching, and they will continue to hunt until every last prey is gone from that area,” McGregor says. “It's an extra level of meticulousness that a lot of native predators don't tend to have. I feel like cats are more the mop-up crew.”
In the near term, conservation biologists are scrambling to save animals now caught out in the open with no food or water, by for instance deploying feeding stations. Australia has even begun airdropping vegetables, for example carrots for wallabies. One wildlife rescue group is distributing pellets for locals to feed suffering animals. “We've never contemplated things like this in the past,” says Legge. “But just to try and get a few individuals through the crunch, that might be necessary.”
They also have to control feral predators like foxes (introduced in the 19th century for recreational hunting) and cats, by hunting and trapping them. “There is a lot to do, and it all has to happen very fast,” says Legge. “So there's people scrambling all over the place, trying to get a lot of these actions prioritized, coordinated, and then implemented.”
Not all species will make it. The Kangaroo Island dunnart, for example, is a tiny marsupial that appears to have lost 95 percent of its habitat to recent bushfires. “It was already very rare,” says Legge. “These fires are potentially catastrophic for that species.” At least one individual has been found alive, and if conservationists can find and breed more, perhaps they can save the dunnart from doom. But only if the cats don’t get there first.