Among the perils of city life that birds and other animals share, the most uniformly serious one is the domestic cat that ventures out-of-doors. . . . [I]n the United States . . . cats kill 6.9 to 20.7 billion small mammals each year. Suddenly the slaughter of more than three hundred million vertebrates—birds, herps, and mammals—on U.S. roads seems tiny. Cats eat at least an order of magnitude more animals than we run over with our cars each year. And it is mostly a different set of animals that cats eat; Fluffy doesn't eat many deer or salamanders, but she really tears up the mice, birds, and small reptiles.John M. Marzluff, Welcome to Subirdia: Sharing Our Neighborhoods with Wrens, Robins, Woodpeckers, and Other Wildlife (New Haven: Yale Univ. Press, 2014), p.