Some 143 million mammals, 2.46 billion reptiles, 180 million birds and 51 million frogs were impacted by the country's worst bushfires in decades, the WWF said on Tuesday.
When the fires were still blazing, the WWF estimated the number of affected animals at 1.25 billion. The fires destroyed more than 11 million hectares (37 million acres) across the Australian southeast, equal to about half the area of the United Kingdom.
"This ranks as one of the worst wildlife disasters in modern history," said WWF-Australia Chief Executive Officer Dermot O'Gorman in a statement.
Project leader Lily Van Eeden, from the University of Sydney, said the research was the first continent-wide analysis of animals impacted by the bushfires, and "other nations can build upon this research to improve understanding of bushfire impacts everywhere".
The total number included animals which were displaced because of destroyed habitats and now faced lack of food and shelter or the prospect of moving to habitat that was already occupied.
Researchers said the destruction will see some species become extinct before their existence is even recorded.
"We don't even know what we are losing," said Chris Dickman, Professor in Ecology at the University of Sydney.
"These were species that were here and now they have gone... It's almost too tragic to think about."
The main reason for raising the number of animal casualties was that researchers had now assessed the total affected area, rather than focusing on the most affected states, they said.
After years of drought made the Australian bush unusually dry, the country battled one of its worst bushfire seasons ever from September 2019 to March 2020, resulting in 34 human deaths and nearly 3,000 homes lost.
