Two years ago, New Zealand embarked on an ambitious effort to rid the country of every single rat, stoat, and possum. The invasive mammals were killing around 25 million of the country’s native, flightless birds each year, and the government wanted to give its rare fauna a chance at survival. If New Zealand stopped controlling its invasive mammal populations, “we would lose more than 95 percent of our native birdlife,” says Dan Tompkins, who’s in charge of the science strategy for Predator Free 2050 Limited, a government-created company tasked with making this plan a reality. Tompkins feels strongly that the government’s plan is the right thing to do for New Zealand’s native fauna, but he knows it won’t be easy. “We can do pretty well at getting them down to low enough numbers that benefits the native biodiversity, but if we really wanted to eradicate, and eradicate large areas, we are going to need something new,” he says. He means new killing tools.