In the field of conservation, success stories about saving individual species abound. Bald eagles have recovered from their bout with the pesticide DDT; from fewer than 500 breeding pairs in 1963, the population in the lower 48 states has grown to nearly 10,000 breeding pairs, such that they are no longer listed even as threatened under the Endangered Species Act. Gray wolves have returned to Yellowstone National Park, as well as to the Italian and French Alps. The California condor has been brought back from the absolute brink of extinction, after the last surviving birds were rounded up and bred in the San Diego and Los Angeles zoos. And so on.

When human ingenuity and resources are trained on a particular species, usually a charismatic one, it makes a difference—but it does not change the global pattern, which is a steady drumbeat of extinction and of the permanent loss of biodiversity that goes with it. In a recent global assessment, Stuart Butchart and his colleagues at BirdLife International in England concluded that between 1994 and 2004 conservation efforts had saved 16 species of bird from extinction, at least temporarily. During that same decade, however, another 164 bird species listed as threatened by the International Union for Conservation of Nature (IUCN) had slipped a notch closer to extinction.

If your institution has site license access, enter here.