Australian wildlife experts are in a race against time to save dozens of threatened species from extinction amid unprecedented bushfires that have already burnt through 8-10 million hectares. Fires that have raged across the country’s south-eastern states for months have had a devastating impact on Australia’s unique flora and fauna, killing an estimated one billion native animals. While harrowing footage of dead and injured koalas and kangaroos has shocked people around the world, there are now fears that entire species could be wiped out as fires destroy crucial conservation areas. Small marsupials with already dwindling populations and limited geographical reach, such as potoroos and dunnarts, are particularly at risk. John Woinarski, professor of conservation biology at Charles Darwin University, estimated that 20 to 100 threatened plants and animal species would have had most of their range burnt. "Many of those not killed immediately by fire would have succumbed in the weeks after fire because the blackened landscape of their former homes would be without food or shelter," Mr Woinarski told <em>The National</em>. “Hopefully none of them have been completely eliminated. Even if the fires have not definitively caused any extinctions, they have undoubtedly increased the extinction risk for many species.”\ He said threatened species with small ranges were of the greatest concern, citing the long-footed potoroo, which has a scattering of small populations mostly in the forests of East Gippsland, which is among the most severely burnt areas. The Kangaroo Island dunnart, a small insectivorous marsupial similar in size to a mouse, has also lost most of its habitat to the fires in recent days, as has the Glossy Black Cockatoo, another resident of the popular tourist island off the coast of South Australia. Concerns have also been raised for Australia’s unique amphibians, invertebrates and reptiles, including the alpine bog skink – a species of lizard which is unusual as it bears live young. In a rare glimmer of hope, at least one of Kangaroo Island’s dunnarts was detected at a monitoring site on Wednesday, said Pat Hodgens, an ecologist in Australia's Land for Wildlife programme . “This is fantastic news but we must work hard to protect them from predation by feral cats and locate other remnant patches to find more survivors,” Mr Hodgens said. Camera traps set up to monitor the dunnarts were destroyed, making it harder to gather data on how many of the 300-strong population have survived. This has become a common problem across the fire-ravaged areas, where ecologists are working to gather information on where to direct the most urgent attention. While it is not possible to complete a definitive survey while the fires are still burning, several conservation agencies and groups are now overlaying distribution maps of threatened species with fire mapping, Mr Woinarski said. “This should identify those species that are likely to have suffered greatest proportional population losses. We will then try to survey for these species to see whether there may be unburnt refuge patches within their range, in which they may have persisted.” Beyond the immediate impact of the fires, burnt land presents compounding challenges, including lack of food and shelter, and increased predation by non-native species. “We know that feral cats and the introduced red fox hunt most effectively in and around burnt areas because there is so little shelter remaining for native animals,” Mr Woinarski said. “There will be a priority to try to control these pests in any areas where threatened species remain.” Vegetation regrowth can also encourage the spread of other pest species, such as deer. Mr Woinarski said the fires were part of a “wicked package” of extensive and long-lasting drought and extreme heat events that had harmed many species. “Because rainfall triggers reproduction for many species, and there has been little rainfall in many areas for several years, many species will be undergoing a demographic collapse with no recruits in the population,” he said. “Also, many Australian species have fared poorly in record maximum temperature events”. While many community groups and wildlife carers are nurturing injured wildlife, this alone cannot solve the conservation problem, he said. “We need also to help find and better protect those important unburnt patches in largely burnt landscape, initiate targeted control of pests and weeds, establish nest boxes and other habitat features, and in some cases catalyse re-vegetation.” “We need also to reduce the likelihood of future catastrophic fires. This needs action to try to control global climate change.” On Wednesday, Ecologists at the University of Sydney updated estimates for the number of animals killed or injured in the fires nationally to one billion. They also almost doubled earlier estimates for the number killed in New South Wales alone to 800 million. In order to reach the “highly conservative” figure, the researchers cross-referenced estimates of mammal population density in NSW with areas of vegetation known to have been scorched to work out the death toll, which includes birds, reptiles and mammals – excluding bats, but not insects or amphibians. Professor Andrew Beattie of Macquarie University said the death toll nationwide could be in the billions "if you think of mammals and birds and reptiles, amphibians and, say, the larger insects such as butterflies". "We can be pretty sure that in large parts of these very expansive fires, most of the wildlife will be dead," Mr Beattie told the AFP news agency. "The flora and fauna will be gone, and that includes the smaller animals which form the food chain for the bigger ones, which people often don't think about." Koala populations have been hit particularly hard because they live in trees, feed only on certain types of eucalyptus leaves and cannot move quick enough away from the flames. While the charismatic marsupials are not at immediate risk of extinction, the fires have exacerbated their decline. About 25,000 of Australia’s only disease-free koala population is feared to have been killed. Kangaroo Island’s koalas are considered an insurance population for the species as they are free from chlamydia – a bacterial infection which causes blindness, infertility and death – which is widespread elsewhere. "Over 50 per cent [of the population] has been lost," Sam Mitchell of Kangaroo Island Wildlife Park, which is raising funds to care for the injured koalas, told AFP. "Injuries are extreme. Others have been left with no habitat to go back to, so starvation will be an issue in coming weeks." Rescuing countless injured animals is also taking its toll on their human carers, who often have to make the hard decision to euthanise creatures that cannot be saved. “We are seeing a lot that are too far gone. We are seeing kangaroos and koalas with their hands burned off – they stand no chance. It's been quite emotional,” Mr Mitchell said.