An endangered species is a type of organism that is threatened by extinction. A species can be listed as endangered at the state, federal, and international level. The International Union for Conservation of Nature (IUCN) Red List lists the global conservation status of many species, and various other agencies assess the status of species within particular areas. A species is classified as endangered when its population has declined between 50 and 70 percent, measured over 10 years or three generations of the species, whichever is longer. A species is also classified as endangered when its population has declined at least 70 percent and the cause of the decline is known. A species is deemed threatened or endangered when it is on the verge of extinction or extirpation. Endangered species may be at risk due to factors such as habitat loss, poaching, and invasive species. The Endangered Species Act (ESA) was enacted by Congress in 1973, and under the ESA, the federal government has the responsibility to protect endangered species, threatened species, and critical habitat. The effectiveness of the Endangered Species Act has been questioned by business advocacy groups and their publications but is nevertheless widely recognized by wildlife scientists who work with the species as an effective recovery tool. The IUCN Red List also re-assesses how species are doing over time, and if things have improved for a given species, then that species will be ‘downlisted’ to a less critical status.
In summary, endangered species are organisms that are at risk of extinction due to factors such as habitat loss, poaching, and invasive species. The International Union for Conservation of Nature (IUCN) Red List lists the global conservation status of many species, and various other agencies assess the status of species within particular areas. The Endangered Species Act (ESA) was enacted by Congress in 1973, and under the ESA, the federal government has the responsibility to protect endangered species, threatened species, and critical habitat.
