In 2006, about 69 million U.S. households had pets, giving homes to around 73.9 million dogs, 90.5 million cats, and 16.6 million birds, and spending more than 38 billion dollars on companion animals. As never before in history, our pets are truly members of the family. But the notion of "companion species"—knotted from human beings, animals and other organisms, landscapes, and technologies—includes much more than "companion animals."