Species endangerment patterns in the United States

The single-species approach to conserving threatened and endangered species in the United States is insufficient, given the number of species (more than 700) officially considered at risk of extinction (i.e., formally listed under the Endangered Species Act of 1973), the rate at which new species are being listed (more than 50 species a year), and the number of species awaiting listing (more than 3,500 candidate species). Regions supporting many endangered species were located in the humid Southeast and the arid Southwest, and tended to be unique with respect to taxonomic composition, prevalence of endemism, climate, land-type associations, and factors contributing to species endangerment. A comparison of the state-level distribution of candidate, Category 1 species indicated that general spatial patterns would remain consistent with the present distribution of endangerment regions; only the Pacific Northwest emerged as a new concentration of endangered species. Directing land management and policy considerations to endangerment regions could increase the efficiency (e.g., multiple species benefits) of efforts to conserve endangered species.