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How do you know when an animal is becoming endangered or extinct? What are the determining factors?

Extinction and endangerment have a scientific and a legal (or regulatory) basis. An example of an extinct species is the Passenger Pigeon (Ectopistes migratorius). The species went from abundant in the 19th century to extinction early in the 20th century. The last known Passenger Pigeon died in 1914. Extinction has been attributed to European settlement and mass deforestation, as well as commercialization of the meat and hunting on a massive and mechanized scale.

The Endangered Species Act (ESA) provides legal authority to protect and recover imperiled species and the ecosystems upon which they depend. Imperiled species may be listed as either endangered or threatened. 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 within the foreseeable future.

Species are classified as Endangered or Threatened on the basis of a five factor analysis. The factors are:

  • Presence of threatened destruction, modification, or curtailment of its habitat or range
  • Over utilization for commercial, recreational, scientific, or educational purposes
  • Disease or predation
  • Inadequacy of existing regulatory mechanisms to protect the species
  • Other natural or anthropogenic factors affecting the continued existence of the species.

Geographically extensive (worldwide and by regions) species assessments are given in the IUCN (International Union for Conservation of Nature) Red List.

The USGS conducts cooperative research and monitoring on endangered species and of on their habitats

Tags: Ecosystems, Disease, Rivers, Water, Health, Ecology, Streams