As fires rage across Australia, fears grow for rare species | Science

Until recently, the Ngunya Jargoon Indigenous Protected Area here in the state of New South Wales (NSW) had the healthiest remaining population of the northern long-nosed potoroo, a hare-size wallaby that feeds on truffles that grow around the roots of gum trees. But in October, after an unprecedented drought reduced the forest to tinder, an intense blaze incinerated the preserve. When ecologists and rangers returned to survey the damage they found no sign of the endangered marsupial, which had declined to a few hundred animals. Now, “The future of the largest known population is in serious doubt,” says Mark Graham, an ecologist with NWS’s Nature Conservation Council, who has worked for 20 years to protect the potoroo.

It isn’t the only Australian species facing potentially catastrophic losses as a result of the unusually severe and widespread wildfires that have so far burned some 3 million hectares in the eastern states of Queensland and NSW—an area nearly the size of Belgium. The blazes, which have hit both arid, fire-prone ecosystems and typically fireproof wetlands and rainforests, have already destroyed the habitats of dozens of rare animals and plants. Worse news may be coming: Peak summer fire season still has 2 months to go, and the already parched region is bracing for another heat wave.

“There’s little question that threatened species are going to be affected; even common species are being pushed towards becoming vulnerable by the size of these fires,” says Euan Ritchie, an ecologist at Deakin University in Melbourne.

The fires have prevented researchers from reaching many study sites to fully assess the damage. As a result, “We are in the fog of war,” says David Bowman, director of the Fire Centre Research Hub at the University of Tasmania in Hobart. But satellite images and other data sources paint a grim picture. Some scientists have even watched in horror as the automated camera traps they use to monitor wildlife instead have captured flames reducing their study sites to ash.

In NSW, which covers a large part of southeastern Australia, at least 20% of the area protected by national parks has gone up in flames. Affected areas include at least 35 of the 41 total reserves scattered across both the Greater Blue Mountains World Heritage Area, west of Sydney, and much of the Gondwana Rainforests of Australia World Heritage Area in the north of the state. Officials estimate about 48% of the iconic Gondwana reserves, which include rainforests that have existed since the time of the dinosaurs, have now burned.

Maurizio Rossetto, an evolutionary ecologist at the Royal Botanic Garden Sydney, says that in Nightcap National Park, one of the Gondwana reserves, he fears for about 30 rare tree species and a similar number of rare animals, because their habitats have likely been destroyed. The park has some of Australia’s most biodiverse forests, “with high proportions of [species from] ancient, endemic lineages that go back to Gondwanan times” more than 60 million years ago. And it is precisely the absence of fire in the forests of Nightcap and nearby reserves that has allowed rare tree species to persist there, Rossetto notes. “Many of these trees have thin bark that does not provide protection against fire,” he says. He is particularly concerned about three species, each of which has just a few hundred remaining trees “tightly grouped in a single population.” 

The Gondwana rainforest’s frogs are also under threat. One species, the pouched or hip pocket frog, is a delicate, 2-centimeter-long amphibian that raises its tadpoles in pouches on its hips. It needs moist leaf litter to survive and “has no tolerance to fire,” Graham says. He suspects the fires have caused “mass mortality” and wonders whether NSW officials will have to reclassify the frog, now listed as vulnerable, as endangered.

In the Greater Blue Mountains, flames have ravaged about 50% of its heritage reserves, threatening regions inhabited by endangered species with small ranges, including a shrub called the Kowmung hakea, a lizard known as the Blue Mountains water skink, and the Wollemi pine, a “living fossil” discovered in 1994.

Ross Crates, an ecologist at the Australian National University in Canberra, notes the mountains are also the “final stronghold” of a critically endangered bird, the regent honeyeater. Just 250 to 400 of these striking black-and-yellow nectar feeders remain, and an estimated 80% of breeding pairs nest in the Greater Blue Mountains. The fires have so far destroyed honeyeater nesting sites in at least five valleys; some had nests that still held chicks. He’s also lost about 10% of the 1200 honeyeater monitoring stations he set up over the past 5 years, which can include cameras and other sensors.

Farther west in NSW, well into Australia’s inland, another endangered bird faces new peril. The Australasian bittern inhabits the Macquarie Marshes, an internationally significant protected wetland that supports hundreds of thousands of water birds during times of plenty. But Australia’s lengthy drought has deprived the marsh of water, and in October fire burned through
3000 hectares, eliminating 90% of the reed bed, the bittern’s key nesting habitat.

In Queensland, which covers northeastern Australia, researchers fear fires have consumed key habitats within Bulburin National Park, which harbors an endangered native macadamia reduced to fewer than 150 remaining trees. Satellite images suggest fire may have reached all three parts of the park that have the trees, says Diana Fisher, a mammal ecologist at the University of New England in Armidale. The Bulburin fires also menace the silver-headed antechinus, an endangered shrew-size marsupial carnivore. Just a few hundred individuals remain, and Bulburin has the largest of the three known populations.

Researchers say even animals that survive the fires are likely to face long-term challenges. Some silver-headed antechinus, for instance, might have escaped the heat by squeezing into rock crevices, Fisher says. But they may emerge to find little shelter or food. “If they lose all of their leaf litter and ground cover, then they’re not going to persist,” she says. In the past, antechinus from other areas might have repopulated vacated territories, she adds, but habitat fragmentation now makes that nearly impossible.

Surviving potoroos, too, will likely have to avoid cats and foxes, introduced predators that move into disturbed forests “and quickly mop up ground-living wildlife,” says Mike Letnic, an ecologist at the University of New South Wales here. “It’s like a double whammy.”

More mobile animals, such as adult honeyeaters, probably fled from trouble. But the specific types of rare gum tree blossoms that the honeyeaters prefer to feed on, and nest near, could be in short supply. “It’s about the long-term cumulative impacts on breeding success, rather than death of individuals,” Crates says. “For a species already on the brink of extinction, it’s not great.”

The fires have amplified many scientists’ complaints that Australia’s current government, led by Prime Minister Scott Morrison, has failed to acknowledge the role of climate change in the drought and fires, and has done little to cut national greenhouse gas emissions. The looming question, scientists say, is whether climate change will make catastrophic fire seasons like this one—which started unusually early—the norm in Australia. If so, Ritchie and other researchers say, even Australian species and habitats with some level of fire tolerance may face existential threats.