What is the Endangered Species Act and how do species get listed?

The Endangered Species Act (ESA) is a conservation law that is jointly administered by the U.S. Fish and Wildlife Service and the National Marine Fisheries Service. The purpose of the law is to "protect and recover imperiled species and the ecosystems upon which they depend" (ESA Overview). Species may be listed as 'endangered' or 'threatened'. The Service uses an Species Status Assessment framework to gather information needed to help inform the decision.

A Species Status Assessment (SSA) is used to better understand the species and inform the ESA decision. This scientific assessment is both repeatable and rigorous and seeks to evaluate the ability of a species to maintain self-sustaining populations over time. Upon its completion, the SSA provides not only an ESA listing decision, but also includes consultations, grant allocations, permitting, habitat conservation plans and recovery planning. 

To read the ESA in its entirety, review a fact sheet, or find more information on the Species Status Assessment, visit the U.S. Fish and Wildlife Service website. You can read the SSA for monarchs here.