If you want to get into a blistering argument on the internet, just bring up feral cats, the descendants of our favorite domestic mouse catchers that are now living wild. While advocates argue they aren’t harming anyone and should be left alone, many conservationists see free-ranging cats as an environmental catastrophe. Recent studies suggest that in the United States alone, outdoor and feral cats kill 2.4 billion birds per year and as many as 12.3 billion small mammals. The U.S. is not the only place where the cuddly killers strike: Yasemin Saplakoglua at LiveScience reports a new study shows that feral cats in Australia are gobbling up over 1 million lizards a day, pushing some species to the brink of extinction.
To come up with that estimate, researchers looked at 80 previous studies that investigated cat predation on lizards, snakes and other reptiles, studying poo and stomach samples to determine how many and what types of creatures 10,000 Aussie cats ate. Cats, it turns out, aren’t picky when it comes to little reptiles. Researchers found 258 different species of reptiles in the samples, including 11 threatened species. The cats even snacked on some turtles.
According to AFP, the herps aren’t just an occasional kitty treat. “On average each feral cat kills 225 reptiles per year,” John Woinarski of Charles Darwin University, lead author of the study in the journal Wildlife Research, says. “Some cats eat staggering numbers of reptiles. We found many examples of single cats bingeing on lizards, with a record of 40 individual lizards in a single cat stomach.”
All told, extrapolating from the data, the researchers estimate the feral cat population in Australia, which totals between two and six million, now gobbles up 596 million lizards per year. Add in domestic pet cats that are allowed to roam outdoors and the total number jumps to 649 million reptiles lost to felines each year. That’s on top of 316 million birds cats kill annually in Australia.
Writing at The Conversation, the study authors say all that kitty carnage is likely taking a toll on Australia’s wildlife. “Such intensive predation probably puts severe pressure on local populations of some reptile species. There is now substantial evidence that cats are a primary cause of the ongoing decline of some threatened Australian reptile species, such as the great desert skink.”
Wildlife biologist Imogene Cancellare, not involved in the study, tells Maddie Stone at Earther that the new paper shows that cats fighting for survival in Australia’s hot, dry interior regions are gobbling up the most reptiles. “This means that in hot climates, feral cats are taking even more reptiles in order to survive,” she says. “As climate change continues to threaten biodiversity worldwide, the impact of feral cats will be felt even more severely than it is today.”
In fact, according to previous research, cat predation has been linked to the extinction of 20 mammal species in Australia already. That led the Australian government to initiate a cull in which it is trying to get rid of 2 million feral cats by 2020, reports Julie Power at The Sydney Morning Herald. "We are not culling cats for the sake of it, we are not doing so because we hate cats,” Australia’s Threatened Species Commissioner Gregory Andrews tells Power. “We have got to make choices to save animals that we love, and who define us as a nation like the bilby, the warru ([also called the] black-footed rock-wallaby) and the night parrot.”
People are getting creative to keep the cats out. Just last month, reports Brigit Katz at Smithsonian.com, the Australian Wildlife Conservancy switched on a 27-mile-long electric catproof fence, the largest in the world, to create a 23,000-acre cat-free preserve in Central Australia. The island nation of New Zealand, which is also seeing many of its iconic native species threatened by nonnative predators, has launched an even more ambitious project called Predator Free New Zealand. The goal is to rid the nation, which has no native land mammals besides bats, of feral cats, rats, possums, stoats and other predators by the year 2050.
In the United States, it’s unlikely we’ll see any wide-ranging control efforts like in Australia and New Zealand. Here, animal rights activists and ecologists have been squaring off for the last decade over a practice known at trap, neuter, and return, in which feral cats are captured, sterilized and vaccinated, then allowed to roam free. While that may, over time, help reduce the cat population, it still means billions of wild animals will become Fancy Feasts for years to come.