Measuring progress in US endangered species conservation.

Since passage of the Endangered Species Act in 1973, over 1300 endangered and threatened species have been protected in the USA and its territories. Most species continue to face a significant risk of extinction, but the status of many species is improving. Here we present analyses of federal agency reports to the United States Congress (1988-2002) that describe differences in species status and show which variables are correlated with improving or declining status. We found that 52% of species showed repeated improvements or were not declining over this time. Species status improves over time, with only 35% still declining 13 years or more after protection. Taxonomy, funding by US Fish and Wildlife Service and National Oceanic and Atmospheric Administration, and agency assessment of risk of extinction and potential to recover were significantly correlated with status.