Kitty may be cute and cuddly, but it also is a real killer. A new report from two federal agencies says that domestic cats, both pets and strays, are responsible for killing billions of birds and small mammals each year in the United States.

Scientists from the Smithsonian Conservation Biology Institute and the Fish and Wildlife Service (FWS) estimated that cats take down 1.4 to 3.7 billion birds and 6.9 to 20.7 billion mammals annually, including shrews, chipmunks and voles.

The numbers mean that cats kill off more birds and mammals than cars, pesticides, and collisions with buildings, making the felines one of the biggest threats to wildlife in the nation.

“When we ran the model, we didn’t know what to expect,” Dr. Peter Marra, who performed the analysis with FWS colleagues, told The New York Times. “We were absolutely stunned by the results.”

The scientists noted that the majority of the kills are done by feral cats, while free-roaming pets accounted for only about 29% of the birds and 11% of the mammals killed.

Cats were responsible for the extinction of 33 island-based species of reptiles, birds and mammals, according to a previous study by the International Union for Conservation of Nature.

This feline threat is behind New Zealand philanthropist Gareth Morgan’s call for the extermination of his country’s cats as a means of saving the nation’s rare wildlife species.

-Noel Brinkerhoff

To Learn More:

That Cuddly Kitty Is Deadlier Than You Think (by Natalie Angier, New York Times)

Biologists: Pet Cats Kill Up To 3.7 Billion Birds and 20.7 Billion Mice Annually (Agence France-Presse)

The Impact of Free-Ranging Domestic Cats on Wildlife of the United States (by Scott R. Loss, Tom Will and Peter P. Marra; Nature Communications)

Study Shows People Who Look at Photos of Cute Animals Perform Tasks Better (by Noel Brinkerhoff, AllGov)

The Government Program that Kills Wild Animals (by Noel Brinkerhoff and David Wallechinsky, AllGov)