In northern Australia, mammal populations are in free fall. Over the past 2 decades, scientists have documented sharp declines in quolls, bandicoots, and other native fauna. The plight of these animals has grown so desperate that in July, the Australian government appointed the nation's first threatened species commissioner, Gregory Andrews, a Department of the Environment staffer now tasked with devising broad approaches to stem the tide of extinctions. The solutions are not obvious, but mounting evidence points to the arch villain: feral cats, aided and abetted by fire. The Australian Wildlife Conservancy estimates that every day in Australia, an astounding 75 million animals fall prey to roughly 15 million feral cats.