How is a species listed?:  For a species to be listed at any level, there must be a status review of the species population and habitat.  This extensive scientific analysis, which is performed by either the U.S. Department of Fish and Wildlife (USDFW), the State Department of Fish and Wildlife, the National Oceanic and Atmospheric Administration (NOAA), or the National Marine Fisheries Service (NMFS), is then taken into consideration for any proposed listing.

Once a species is listed:  For every species listed as Endangered or Threatened it is listed in the federal or state Register and is protected by a number of rules and regulations, which differ depending on the species and its habitat.  Also, once a species is listed, either the USDFW, the State Department of Fish and Wildlife, NOAA, or the NMFS propose and implement a recovery plan based on the data from the status review report.  From there, the species is monitored for improvement or decline and then either continues to hold its listed status or is proposed for downlisting (Endangered to Threatened for example), delisting (removed from ESA protection), or relisted (Threatened to Endangered for example).  While listed, each species is by law under federal and / or state protection.  According to the ESA itself, it is illegal to "harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, collect, or attempt to engage in any such conduct" with regard to an endangered or threatened species.  In addition, the body parts and products of endangered or threatened species cannot be imported, exported, or sold.

Extinct = A species that once lived on earth and no longer does.  These populations are considered to be of history and are gone forever.  Although currently, the term extinction holds many negative connotations, extinction is nothing new.  In fact, extinction is apart of life and has been occurring since life began on Earth.  However, today extinction is considered to be occurring at alarmingly fast rates.

Endangered = The Endangered Species Act of 1973 defines an endangered species as any plant or animal species that is in danger of extinction throughout all or a significant portion of its range.  In other words, these are populations which are still alive today but exist in numbers so low or are decreasing so rapidly that they are in immediate danger of extinction.

Threatened =  The Endangered Species Act of 1973 defines a threatened species as one that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range if factors contributing to their population decline or habitat degradation or loss continue.  In other words, this is a species populations which has been in decline and unless some type of protective measures are put into place, this species will be Endanger (in danger) of becoming extinct.

Candidate Species =  These are plant and animal species that can be thought of as being under review.  For these species, scientific data exists to indicate that their populations are not stable.  These populations are considered to be in need of ESA protection.

Species of Concern = These are species which are believed to have declining populations and/or habitat.  Yet, due to the lack of scientific data, these populations can not yet be categorized within the state or federal threatened, endangered, or candidate species lists.