Australia has one of the worst mammal extinction rates in the world. And cats are partially to blame. Of the 21 completely extinct marsupials and rodents in Australia, the cat and the red fox have likely contributed to the extinction of all but two. Feral cats are also a threat to 35 bird species, 36 mammal species, seven reptile species and three amphibian species. Four of those are critically endangered. Feral cats are everywhere across Australia and in big numbers: the government has put the figure at around 18 million. But it’s not just ferals that are to blame for killing wildlife. Domestic pet cats that are allowed outdoors are just as effective predators. Cat owners who claim their pets don’t hunt may not even realise what’s happening; a recent study found that cats only bring home about a quarter of their kills. Conservationists and wildlife groups say something needs to be done to reduce the impact of cats on native wildlife. But they can’t agree on what.