Species Missing Endangered Species Act Protection

Cerulean Warbler / Photo by Lana Hays

It is no secret that the Endangered Species Act gives incomplete protection to vulnerable species in the United States. Not all vulnerable species are listed, and even when a species is listed, a recovery plan may take years to create or lack adequate funding. A new study attempts to quantify just how many species lack Endangered Species Act protections.

A study - now published in Conservation Letters - has compared the ESA list of endangered species with the world's leading threatened species list, the International Union for the Conservation of Nature (IUCN) Red List.

The study has found that of the American species included on the IUCN Red List, 40% of birds, 50% of mammals, and 80-95% of other species such as amphibians, gastropods, crustaceans, and insects, were not recognised by the ESA as threatened.

This amounts to approximately 531 American species on the IUCN Red List that have not made the ESA protection list. These include bird species such as the critically endangered Kittlitz's murrelet (Brachyramphus brevirostris), the endangered ashy storm-petrel (Oceanodroma homochroa), and the vulnerable cerulean warbler (Dendroica cerulea).

"The ESA has protected species since its establishment in 1973, and it may have prevented 227 extinctions. However, the implementation of the ESA by successive US governments has been problematic, including poor coverage of imperilled species, inadequate funding, and political intervention," says study leader Bert Harris, a native of Alabama who is undertaking his PhD with the University of Adelaide's Environment Institute and School of Earth & Environmental Sciences.

"Vague definitions of 'endangered' and 'threatened' and the existence of a 'warranted but precluded' category on the ESA list are also contributing to the gap in species classification," he says.