A billion animals might have been caught in Australia’s wildfires. Some could go extinct.

The mouse-sized dunnart is not as iconic as the koalas or platypuses that draw tourists, but it is arguably the most special mammal on Australia’s Kangaroo Island.

Now the Kangaroo Island dunnart's days may be numbered. Before bush fires struck, it was already endangered, so rare that even researchers who studied them had never seen one. Now they fear they never will. One-third of the 1,700-square-mile island has burned, including the entire area where these dunnarts are known to live.

"One hundred percent - all of our records since 1990 are within the burned fire scar. The entire range of the species has been burned," said Rosemary Hohnen, an ecologist who spent more than two years surveying the Kangaroo Island dunnart. "They're in true peril, real peril of extinction."

More than one billion mammals, birds and reptiles nationwide - some of them found nowhere else on Earth - may have been affected or killed by the fires sweeping across Australia, according to a University of Sydney estimate. The potential toll is far greater when other types of animals are included.

"We're not just talking about koalas, we're talking mammals, birds, plants, fungi, insects, other invertebrates, amphibians and bacteria and microorganisms that are critical to these systems," said Manu Saunders, a research fellow and insect ecologist at the University of New England in Armidale.

Individual animals might survive, but when their habitat is gone, "it doesn't matter," Saunders said. "They'll die anyway."

Although dead and scorched koalas and kangaroos have become the symbols of wildlife suffering in the worst blazes ever to hit fire-prone Australia, conservationists note that koala populations are not at risk of extinction. A greater ecological concern are the unusual animals that could disappear from a continent with the world's highest rate of mammal extinction.

"Extinction of endemic species means, of course, irrevocable loss," said Christopher Dickman, a University of Sydney ecology professor. Dickman initially estimated that half a billion animals were affected before doubling that number in an update. "While one billion is clearly a large number, the expectation is that the number contains examples of many species that are ecologically important."

Among the most vulnerable: the long-footed potoroo, a marsupial that lives in damp forest habitat that scientists say may not recover from the fires, and the Kangaroo Island glossy black cockatoo, which eats nothing but the seeds of she-oak trees that have gone up in flames.

And then there are all the insects, the foundation of a living forest. They make up half of all animal biomass and are the major food source for virtually anything that moves. Bugs also break down organic matter and help pollinate plants. Inside branches, under leaves, within hollowed logs and in pockets on the ground, tens of millions of bugs are being burned alive. Some may vanish without ever being discovered.

"Only about 20 to 30 percent of Australian insects are known to science," said Katja Hogendoorn, a researcher at the School of Agriculture, Food and Wine at the University of Adelaide.

A single bee species shows how grim the outlook is for many. Fires and land clearing had already driven the green carpenter bee to extinction in Victoria and South Australia. Now, said Hogendoorn, fires are threatening them on Kangaroo island.

The banksia plant, which the bees use for nests, have burned. It takes 30 years for it to grow to the right size and softness for the picky bees. "It is difficult to assess the situation," Hogendoorn said, "because there is no access to the burned sites, but the species is likely to be in dire straits."

Climate change, invasive species, overuse of farm chemicals and human development also threaten insects. "The fires could be the last straw that drives fragile populations over the brink," said Tanya Latty, an entomologist at the University of Sydney.

Wild animals aren't the only creatures suffering.

Federal agriculture officials say at least 100,000 cattle will die before the fires end. Farmers say their livestock are keeling over from burns. Cows have stopped feeding calves because their teats are scorched. An army of veterinarians has been assembled to assess those left standing. They’re also weighing how to dispose of the dead.

Stephen Shipton lost 50 cows when fire struck his farm in Coolagolite, a town in New South Wales, on New Year's Day. He knows because he killed dozens of wounded animals himself. "We've lost a third of our herd," Shipton said. "They're still dying. They're just getting sick and other things at this point."

Starvation and disease is part of the damage fire leaves behind.

Animals that survive may struggle to find food in an ashen landscape devoid of plants that provide nutrients or shelter. Without trees to nest in, birds may fail to breed. Prey, including insects, may be scarce.

Studies have shown that two of Australia's deadly invasive predators, cats and red foxes, move into burned terrain and slaughter animals whose protection - vegetation - is gone. At most risk are the Kangaroo Island dunnart and other small animals in "the cat and fox snack range," said Euan Ritchie, an associate professor of ecology and conservation at Deakin University in Melbourne.

This week, flames continued to whip across Kangaroo Island, where conservationists have worked for years to shore up fragile animal populations.

Efforts to protect the nests of the island's subspecies of glossy black cockatoos from deadly attacks by brushtail possums helped the population reach about 400 by 2018, but they are still considered endangered, said Daniella Teixeira, a University of Queensland doctoral student who studies the birds.

The cockatoos - strikingly goth, with harsh calls and large black bodies marked by red or yellow feathers - are favorites of locals, she said. Now, fires appear to have burned as many as six of eight known flock regions, she said.

"Even if we lost a quarter of the birds . . . that could potentially put us back a decade in terms of conservation work," Teixeira said.

The situation looks even more dire for Kangaroo Island dunnarts. They've been detected just 48 times since their discovery in 1969, and they've been seen only in a small western pocket of the island since 1990, Hohnen said.

Last week, Kangaroo Island Land For Wildlife, which works with private landowners to protect the dunnarts, said many of the remote cameras it uses to monitor the marsupials were “melted” by fires. On Wednesday, though, the group said some photos of survivors were captured, offering a bit of hope for the species.

After the fires end, Hohnen and other experts said, the focus must turn to helping animals that remain. That will mean removing invasive predators, and possibly captive-breeding for some species. Replanting trees and other vegetation will be crucial, they said.

So will bolder government action on climate change, some said.

"There's a feeling among the scientific community here that the eyes of the world are on Australia. It's been called the climate canary in the coal mine. The predictions of climate change were expected to be manifest first and most obviously in Australia, because it's already a dry continent," Dickman said. "There's a sense of even greater responsibility, in some ways."

That responsibility should extend to the dunnart, Hohnen said - even if it's not a national icon.

“Biodiversity is part of what makes planet Earth planet Earth. It’s our heritage; it’s our richness,” she said. “They might be just another number that we’re adding to a list of species that are going extinct. But that number is important.”