Katherine Moseby wanted to be clear: She does not hate cats. “They’re a wily beast,” she said, as her truck rumbled down a desert road. “But I respect them. They’re pretty incredible animals. Amazing hunters. Very smart.”

That was precisely the problem, said Dr. Moseby, the principal scientist and co-founder of Arid Recovery, a conservation nonprofit and wildlife reserve in South Australia. Cats are not native to Australia, but they have invaded nearly every corner of the country. She gestured out the window at the dusty, red expanse, which bore few signs of life. But feral cats were absolutely out there, Dr. Moseby said, and they had a taste for the tiny, threatened marsupials that lived at Arid Recovery.