Feral cats are destroying native wildlife at a rate far greater than previously understood, according to a study that applied forensic DNA analysis to the predators’ gut contents. Researchers at the University of New South Wales found that Australian feral cats may be killing twice as many mammal species and three times as many bird species as earlier surveys had indicated. The work, published in the journal Wildlife Research, concludes that a widely cited review—which estimated 1.5 billion native animals killed annually—greatly underestimates the true toll.

The discrepancy arises because traditional diet studies rely on visually identifying hair, bones and feathers in scat or stomach samples, a method that misses soft-bodied prey and tiny fragments degraded by digestion. By creating a genetic “barcode” for each prey item, the team detected remains that would otherwise go unrecorded, including soft-bodied New Zealand frogs appearing more often than expected. The findings have direct implications for invasive-predator monitoring, the authors note, because detecting rare species is crucial to effective conservation.

The real-world consequences of such predation are stark. On New Zealand’s Purerua peninsula, a single large feral tabby nicknamed “Nine Lives” evaded trappers for three years and killed dozens of pāteke—the country’s rarest mainland duck—amounting to roughly 1 percent of the population, along with kiwi chicks and native geckos. The cat was finally shot on 30 July after a baited cage trap succeeded, and its body will be taxidermied as an educational tool. New Zealand, which has an estimated 2.5 million feral cats, recently added the species to its Predator-Free 2050 strategy.

A counter-example from Japan’s Ogasawara archipelago shows how rapidly ecosystems can respond when cats are removed. After 131 feral cats were relocated from Chichijima island between 2010 and 2013, the red-headed wood pigeon population surged from 111 adults to 966, and juveniles from 9 to 189. A Kyoto University team reporting in Nature attributed the recovery to the removal of predation pressure, though they cautioned that the pigeon’s low genetic diversity—a legacy of centuries of isolation—leaves it vulnerable to disease and environmental change.

Researchers in both Australia and Japan are calling for complementary measures. The Australian team advocates fenced “safe havens” to shield the most at-risk wildlife from cats, foxes and rabbits. The Kyoto group stresses long-term genetic surveillance to ensure that recovering populations do not later collapse. The next milestone to watch is whether New Zealand’s expanded elimination strategy can replicate the rapid gains seen on Chichijima at a national scale.