Cats kill billions of animals a year according to new study

A new study shows that cats kill billions of animals every year, including birds, tiny rodents and other animals. The journal Nature Communications reports that cats kill between 1.4 billion and 3.7 billion birds and between 6.9 billion and 20.7 billion small mammals annually.

This study was co-authored by Pete Marra, an animal ecologist at the Smithsonian Conservation Biology Institute. He says that these deaths of may account for as much as 15 percent of the total bird population. The cause of most of these deaths are wild, un-owned cats versus domesticated ones, he tells LiveScience.

While an average household cats kills anywhere from four to 18 birds and eight to 21 small animals a year, a wild one can kill between 23 and 46 birds and between 129 and 338 mammals annually. A potential solution to this wildlife death is to keep cats inside, but it's unclear how that would affect the ecosystem.

Do those numbers surprise you?