Nearly 3 billion animals were killed or displaced by Australia’s devastating bushfire season of 2019 and 2020, according to scientists who have revealed for the first time the scale of the impact on the country’s native wildlife.

The Guardian has learned that an estimated 143 million mammals, 180 million birds, 51 million frogs and a staggering 2.5 billion reptiles were affected by the fires that burned across the continent. Not all the animals would have been killed by the flames or heat, but scientists say the prospects of survival for those that had withstood the initial impact was “probably not that great” due to the starvation, dehydration and predation by feral animals – mostly cats – that followed.

An interim report based on work by 10 scientists from five institutions, commissioned by the World Wide Fund for Nature (WWF), suggests the toll from the fires goes much further than an earlier estimate of more than 1 billion animals killed.

Scientists from the University of Sydney, University of New South Wales, University of Newcastle, Charles Sturt University and Birdlife Australia contributed to the study.

The findings meant it was one of "worst wildlife disasters in modern history", said the World Wide Fund for Nature (WWF), which commissioned the report.

Mega blazes swept across every Australian state last summer, scorching bush and killing at least 33 people. Mammals, reptiles, birds and frogs died in the flames or from loss of habitat.

During the peak of the crisis in January, scientists had estimated that 1.25 billion animals had been killed in New South Wales and Victoria alone.

But the new estimate takes in a larger area. About 11.46 million hectares - an area comparable to England - was scorched from September to February.