Nature means mountains, swamps, oceans, and the night sky, but it also means animals of all sorts. Recognizing their symbolic and emotional power, environmental advocates often use images of wild animals in order to raise both consciousness and money. While wolves in Yellowstone serve as proud symbols of a wilderness that deserves protection, oil-soaked pelicans on Gulf Coast beaches provide concrete images of human destructiveness. However, nature also means more homely animals who live in our backyards, city parks, and even within our houses. Familiar creatures—an owl hooting in a suburban tree, deer paused on the roadside at dusk.

Although animals receive little attention in environmental thought, a growing literature addresses the moral status of nonhuman animals. Like environmental philosophy, animal ethics encompasses diverse theoretical models, including not only rights-based but also Utilitarian, virtue, feminist, and religious frameworks. Animal ethics also identifies a wide range of qualities as the source of value in nonhuman animals, from life itself to sentience, intelligence, sociability, or relations with humans. Almost all animal ethicists, however, agree that nonhuman animals have intrinsic value and should be protected on that basis.