Cats: Cuddly fluff balls or world's worst invasive species?

A study published in December offered science's most complete look at what domestic cats around the globe hunt and consume. The short answer? Absolutely everything, with no regard for any prey's place on endangered species lists. Some of the species found in cats' diets over the past few decades are now extinct, as outdoor domestic cats have spread to every place on earth save for Antartica.

We've long been told to keep cats indoors to save the lives of thousands of birds. But what if they need to be kept indoors to save the lives of ecosystems themselves? What if cats—yes, like the small, purring cutie on your couch right now—were the worst invasive species the world has known? And what if we were their willing accomplices?

GUEST: Christopher Lepczyk, ecologist and professor at Auburn University in Alabama; lead author of "A global synthesis and assessment of free-ranging domestic cat diet"