For 'Cats in Crisis.' Of the world's 37 species of cats, 8 of them reign as big cats. All are top predators in their realm. All are losing ground. They face habitat loss, illegal hunting for skins and other body parts and retaliatory killing when they prey on livestock. Yet conservationists see hope with a concerted effort. As field biologist George B. Schaller writes in his essay, Politics is Killing the Big Cats," 'The great cats represent the ultimate test of our willingness to share this planet with other species.'"