The study, published today in the journal Nature Communications, found that cats kill about 12.3 billion mammals every year and about 2.4 billion birds. By comparison, wind turbines kill just 440,000 birds. Study authors write that "free-ranging cats . . . are likely the single greatest source of anthropogenic [human-caused] mortality for U.S. birds and mammals." (Read more)
Smithsonian animal ecologist Pete Marra told NPR's Veronique Lacapra that Americans own about 84 million cats, of which 40 to 70 percent are allowed outside. About 50 to 80 percent of those are actually hunters, so around 47 million cats, most of them feral, are killing prey every year. Researchers analyzed all available data to estimate about how many bird and small animals cats kill each year.