“The original figure ― the 480 million ― was based on mammals, birds and reptiles for which we do have densities, and that figure now is a little bit out of date. It’s over 800 million given the extent of the fires now ― in New South Wales alone,” he said.

“If 800 million sounds a lot, it’s not all the animals in the firing line,” he added.

That figure excluded animals including bats, frogs and invertebrates. With these numbers included, Dickman said, it was “without any doubt at all” that the losses exceeded 1 billion. “Over a billion would be a very conservative figure,” he said.

An environmental scientist at the World Wildlife Fund Australia, Stuart Blanch, confirmed these estimates, reiterating that, given the expansion of the fires since the last calculations, 1 billion was a modest guess.