Terms and Definitions from the Endangered Species Act

In 1973 the federal government passed a law stating that the U.S. Fish and Wildlife Service (USFWS) was tasked with preserving wildlife by protecting species at risk of extinction. This law, called the Endangered Species Act of 1973 (ESA) gave authority to the USFWS to protect declining species and the habitat critical to their survival. Within this law, many terms were defined that are used to discuss conservation activities. Below we have listed a few of these commonly used terms with a brief definition (www.fws.gov/endangered).

Endangered species- an animal or plant species in danger of extinction throughout all or a significant portion of its range.
Ex: Pallid sturgeon populations have been decimated in the Mississippi River and are now federally protected.

Threatened species- an animal or plant likely to become endangered within the foreseeable future throughout all or a significant portion of its range.
Ex: Loggerhead sea turtles have seen dramatic population declines from human habitat encroachment along nesting beaches and accidental entrapment in commercial fishing nets.

Imperiled species- also known as a ‘species of concern’. An informal term referring to a species that needs conservation action. This may or may not mean the species will be considered for listing in the future by USFWS.
Ex: The Eastern hellbender- populations in some areas are healthy while other areas have seen steep declines from historical levels. Scientists are monitoring the health of hellbender populations.

Extirpated species- a species that no longer survives in regions that were once part of its native range. This species still exists elsewhere in the wild or in captivity.
Ex: Lake sturgeon were extirpated from Tennessee water’s in the 1960s. Since then a re-introduction program has helped restore them to area waters.

Extinct species- a species that is no longer believed to exist alive in the wild or in captivity.
Ex: Passenger pigeons are believed to have been hunted to extinction. The last known individual died in 1914.

-LSF