Millions of years of isolation have shaped Australia’s extraordinary mammal fauna into species unlike anywhere else in the world, from platypus to koalas and wombats.

Tragically, Australia is the world leader in mammal extinctions. About 40 species have gone extinct in the 238 years since European colonisation began, and nearly 80 species are now imperilled. It’s essential we understand what factors caused these extinctions and ongoing decline.

Over many years, scientists have gathered compelling evidence demonstrating predation by introduced cats and foxes has been a key driver. Australian mammals have had millennia living alongside other predators such as wedge-tailed eagles and dingoes. But foxes and cats are extraordinarily capable and ecologically flexible hunters, quite unlike anything Australia’s mammals had confronted before.

Recently, some researchers have questioned whether these introduced predators really are responsible. In our new research, we lay out the clear lines of evidence implicating foxes and cats. For instance, extinct species tend to be small-to-medium mammals, the preferred prey size for these predators. When mammals are returned to fenced, fox- and cat-free areas, their populations often flourish.

Last year, researchers questioned whether there was enough evidence to say feral cats and foxes had contributed to Australian mammal extinctions – and, by implication, their role in the ongoing decline of other threatened mammal species.

Their research drew on three premises relating to extinct and surviving mammals. If cats and foxes caused these extinctions, they argued that these should follow:........

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