Cats are cute, cuddly, and . . . deadly? These popular pets are great hunters. When allowed outdoors, they prey on a wide array of wildlife. This wreaks havoc on local ecosystems—communities of organisms interacting with their nonliving surroundings. Recently, scientists from Auburn University in Alabama collected data on animals killed by cats. It added up to a whopping 2,084 species, 347 of which are threatened or endangered.
Cats are among the most destructive invasive species—non-native organisms that harm the environment—on the planet. If you own a cat, keep it inside, says Christopher Lepczyk, a biologist who led the study. It’s also a good idea to microchip your pet in case it does get out, and to have it spayed or neutered so it doesn’t have unwanted babies. “Cats make great pets,” he says, “but they belong indoors.”