It's estimated that there are as many as six million feral cats in the country, and that they kill some 800 million native animals annually. (Foxes, also introduced by the British, are very nearly as widespread. They are somewhat easier to control, though, because they will more readily eat poison bait.)

Over the last several years, Moseby and her colleagues at Arid Recovery have experimented with two threatened marsupial species: the greater bilby, which looks like a small rabbit with a long nose, and the burrowing bettong, also known as the boodie, which has a squirrel-like face, skinny hind legs, and a long tail. They've added a small number of cats to some of the paddocks and then painstakingly recorded the results. The idea is to put enough pressure on the marsupials to produce behavioural or - even better - evolutionary change, but not so much pressure that all the animals wind up dead.