But the major scourges for wildlife were not those free-ranging, owned-cats, but instead feral and un-owned cats that survive on the streets. Each of those kitties — and the team estimates between 30 million and 80 million of them live in the United States — kills between 23 and 46 birds a year, and between 129 and 338 small mammals, Marra said.
And, it seems, the small rodents taken by felines aren't Norway rats or apartment vermin, but native rodent species such as meadow voles and chipmunks, he added.
No Easy Answers
One obvious step to reduce the mass wildlife death is to keep kitties indoors, Marra said.
Perhaps seeing their furry friends bring in a meadow vole or a cardinal will spur cat owners to say, "Listen, Tabby, we're going to have a heart-to-heart talk about how much time you spend outside," he said.
Wild cats pose tougher questions, because capture and sterilization approaches have varying levels of success depending on the community, said Bruce Kornreich, a veterinarian at Cornell University's Feline Health Center, who was not involved in the study.
While keeping owned-cats indoors is the best way to benefit both kitties and wildlife, a complete cat ban, like the one recently proposed in New Zealand, is probably not the answer, he said.
For one, it's not clear how completely removing cats from outdoors would affect the ecosystem.
"It may be in some cases that cats may also be keeping other species that may negatively impact bird and other small mammal populations in check," Kornreich told LiveScience.
This article originally appeared on LiveScience.com.
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