The Endangered Species Act

For more than a half-century the Endangered Species Act (ESA) has worked to protect species from teetering towards extinction. Here's a brief overview of how it works.

The act was overwhelmingly passed by Congress in 1973 and signed into law by President Richard Nixon. Bison and bald eagles, California condors, the black-footed ferret, and numerous other species all are alive today thanks to the protection and ministrations of the ESA. The law has kept them in the world, and helped them rebound in number and genetic diversity.

ESA measures over the past half century have ranged from the mundane — think fences to keep out invasive predators — to sophisticated tech, such as infecting mosquitoes with a bacteria to disrupt their reproduction.

This groundbreaking piece of legislation prevents the killing, harm, and destruction of listed animals and habitat, promotes survival and recovery operations, and has been credited with preventing the extinction of more than 99 percent of species listed over the last half-century.

Significantly, the act holds the federal government to account, ensuring that its actions do not jeopardize listed species or damage critical habitat. In a landmark 1978 case, the U.S. Supreme Court affirmed the mission of the ESA, stating that the “plain intent” of the statute was “to halt and reverse the trend toward species extinction, whatever the cost." And it has certainly done that and then some.

The U.S. Fish and Wildlife Service (USFWS) oversees land-based plant and animal species as well as freshwater species, while the National Marine Fisheries Service (NMFS) oversees marine species. Each of those agencies internally can nominate species to be considered for listing under the ESA, and outside groups also can petition those agencies to list species.

A species is listed under one of two categories, endangered species or threatened species, depending on its status and the degree of threat it faces. An “endangered species” is one that is in danger of extinction throughout all or a significant portion of its range. A “threatened species” is one that is likely to become endangered in the foreseeable future throughout all or a significant portion of its range

The law provides for adding species to and removing them from the list of threatened and endangered species, and for having those two agencies preparing and implementing plans for their recovery. It also calls for interagency cooperation to avoid "take" [e.g., killing] of listed species and for issuing permits for otherwise prohibited activities; provides for cooperation with States, including authorization of financial assistance.

A species is added to the list when it is determined to be an endangered or threatened species because of any of the following factors:

• the present or threatened destruction, modification, or curtailment of its habitat or range;
• overutilization for commercial, recreational, scientific, or educational purposes;
• disease or predation;
• the inadequacy of existing regulatory mechanisms;
• other natural or manmade factors affecting its survival.

In theory, the process for evaluating whether a species should be listed as "endangered" or "threatened" should move relatively swiftly, but it seldom does. When petitioned to list a species, the USFWS or NMFS are required to make a finding within 90 days of receiving a petition (to the extent practicable) as to whether there is “substantial information” indicating that the petitioned action may be warranted. If this preliminary finding is positive, the agencies conduct a status review. Within one year of receipt of the petition, they must make a finding whether listing is warranted.

Under the ESA, it is the "policy of Congress that all federal departments and agencies shall seek to conserve endangered species and threatened species."