Endangered Species, 2nd Edition, presents information on endangered and threatened mammals, birds, reptiles, amphibians, fish, mollusks, insects, arachnids, crustaceans, and plants. Its 240 entries — including 40 new species added to the 2nd Edition — were chosen to give a glimpse of the broad range of species currently facing endangerment. While well-publicized examples such as the American bison, northern spotted owl, and gray wolf are examined, so, too, are less conspicuous — yet no less threatened — species such as the Australian ant, Cape vulture, and Peebles Navajo cactus. The entries are spread across three volumes and are divided into sections by classes. Within each class, species are arranged alphabetically by common name.
Color locator maps outlining the range of a particular species are included in each entry to help users find unfamiliar countries or locations. More than 200 color photographs provide a more concrete vision of the species. Sidebar boxes containing interesting and related information are also included in some entries. Each volume ends with a further research section composed of books, periodicals, Internet addresses, and environmental organizations. The book listing is annotated. The environmental organizations list — a selected catalog of organizations focusing on endangered species — contains mailing addresses, telephone numbers, Internet addresses (if available), and a brief description of each organization. The volumes conclude with a cumulative index providing access to all the species and subjects discussed throughout Endangered Species, 2nd Edition.