Deadliest Catch

The occasional dead mouse or bird that Fluffy drops on your doorstep may not seem like a great loss for wildlife. But a new study suggests that the cumulative effect of hunting by domestic cats is staggering: Kitties are killing about 8 to 24 billion birds and mammals in the U.S. each year.

Thanks to humans, domestic cats have spread around the world and pushed numerous bird, mammal, and reptile species on islands toward extinction. But people often assume that the number of wild animals killed by cats pales in comparison to the number that die from crashing into buildings, being run over by cars, or other human-related dangers.

The estimates of cat-related deaths in this latest study tell a different story. Domestic cats in the U.S., not including Hawaii and Alaska, kill 1.4 to 3.7 billion birds and 6.9 to 20.7 billion mammals each year, the study authors say in Nature Communications. Cats without owners account for 69 percent and 89 percent of the bird and mammal deaths, respectively.

“Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals,” the team writes. About two-thirds of birds killed by cats are native, as are most of the mammals killed in the suburbs and countryside.

Even though unowned cats are responsible for most of the carnage, cat owners aren’t off the hook. People should make an effort to control their pets by restricting the cats’ time spent outdoors, the team says.Roberta Kwok | 1 February 2013

Source: Loss, S.R., T. Will, and P.P. Marra. 2013. The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications doi: 10.1038/ncomms2380.

Image © Micha Klootwijk |