Does your home accommodate critters of the hairy, feathered, or scaled variety? According to the Humane Society, there are currently 73 million dogs and 90 million cats in homes across the United States. Birds, bunnies, ferrets, and lizards are other popular pets for children. The food, toys, and bedding for these pets (and even the pets themselves) have a significant impact on the environment. Here's how to reduce your pet's ecological paw print.