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SALT LAKE CITY — Cats may be the Internet's best friend, but they're one of wildlife's worst enemies.
It turns out for every cat who likes to spend its time politely stealing food, or playing the shell game, or sorting your laundry, there is a cat that would rather be out hunting down wildlife. Cats kill as many as 3.7 billion birds and 20.07 billion other animals every year in the U.S., according to a new government study published in the journal Nature Communications.
The study — the first of its kind to analyze rates of feline predation — found that cats are responsible for "substantially greater wildlife mortality than previously thought," according to its authors. Cats are likely the greatest source of bird and mammal mortality linked to human settlement.
The researchers, from the Smithsonian Conservation Biology Institute and the U.S. Fish and Wildlife Service, found that most of the birds killed were indigenous to the U.S. As far as rodents go, cats in urban areas were more likely to feast on non-native species, while cats in suburban areas were likely to make a meal out of native wildlife.
The numbers are from both strays and house cats that spend part of the day outside. The researchers said the numbers show cats are a threat to wildlife that is not taken seriously. They noted, though, that only 29 percent of the birds and 11 percent of the mammals killed by cats were killed by house pets. The rest of the deaths were caused by about 80 million stray or feral cats.
Although it is likely to set off a fierce debate between cat owners, environmentalists and animal welfare advocates, many say house cats should not be allowed to roam the neighborhood without supervision.
"We've put a lot of effort into trying to educate people that they should not let their cats outside, that it's bad for the cats and can shorten the cats' lives," Danielle Bays, manager of the community cat programs at the Washington Humane Society, told The New York Times.