Wild cats certainly kill many more other animals than outdoor pet cats. After all, they have to hunt for their food instead of just bug their human companions. But a new study by North Carolina State University zoologists and their colleagues revealed that outdoor pet cats kill between two and ten times as many animals as wild cats in the same size area. Apparently, every year North American pet cats with outside access kill between ten and thirty billion birds and mammals. But according to the new data gleaned from GPS cat collars, our feline friends generally don't venture further than 100 meters away from their home. Still, their hunting can be a real problem when it comes to conservation. From Scientific American:
[…]In some places, including California, Florida, Australia, and elsewhere, cats were an important threat to some species that are already in trouble.
"On one hand, it's kind of good news that the cats aren't going out further abroad, but it's bad news that they're quite likely to have an impact on animals they share space with near their houses," [says North Carolina State University zoologist Roland Kays.]
With so much killing concentrated around people's houses, the positive impacts of urban wildlife—like the beauty of songbirds, or the way small lizards can control insect pests—could get washed away in precisely the areas where those benefits are most appreciated.