An endangered species is a population of an organism which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters. An endangered species is usually a taxonomic species, but may be another evolutionary significant unit. The World Conservation Union (IUCN) has calculated the percentage of endangered species as 40 percent of all organisms based on the sample of species that have been evaluated through 2006. (Note: the IUCN groups all threatened species for their summary purposes.) Many nations have laws offering protection to these species: for example, forbidding hunting, restricting land development or creating preserves. Only a few of the many species at risk of extinction actually make it to the lists and obtain legal protection. Many more species become extinct, or potentially will become extinct, without gaining public notice.
The conservation status of a species is an indicator of the likelihood of that endangered species not living. Many factors are taken into account when assessing the conservation status of a species; not simply the number remaining, but the overall increase or decrease in the population over time, breeding success rates, known threats, and so on. The IUCN Red List is the best known conservation status listing.
Internationally, 189 countries have signed an accord agreeing to create Biodiversity Action Plans to protect endangered and other threatened species. In the United States this plan is usually called a species Recovery Plan.
IUCN Red List Endangered speciesEdit
IUCN Red List of Threatened Species uses the term endangered species as a specific category of imperilment, rather than as a general term. Under the IUCN Categories and Criteria, endangered species is between critically endangered and vulnerable. Also critically endangered species may also be counted as endangered species and fill all the criteria
The more general term used by the IUCN for species at risk of extinction is threatened species, which also includes the less-at-risk category of vulnerable species together with endangered and critically endangered.
IUCN categories include:
- Extinct: the last remaining member of the species has died, or is presumed beyond reasonable doubt to have died. Examples: Thylacine, Dodo, Passenger Pigeon
- Extinct in the wild: captive individuals survive, but there is no free-living, natural population. Examples: Alagoas Curassow
- Critically endangered: faces an extremely high risk of extinction in the immediate future. Examples: Arakan Forest Turtle, Javan Rhino
- Endangered: faces a very high risk of extinction in the near future. Examples: Cheetah, Blue Whale, Snow Leopard, African Wild Dog, Tiger, Albatross
- Vulnerable: faces a high risk of extinction in the medium-term. Examples: Gaur, Lion, Wolverine
- Near Threatened: may be considered threatened in the near future. Examples: Blue-billed Duck, Solitary Eagle
- Least Concern: no immediate threat to the survival of the species. Examples: Brown Rat, Nootka Cypress, Wood Pigeon
Under the Endangered Species Act in the United States, "endangered" is the more protected of the two categories. The Salt Creek tiger beetle (Cicindela nevadica lincolniana) is an example of an endangered subspecies protected under the ESA.
Some endangered species laws are controversial. Typical areas of controversy include: criteria for placing a species on the endangered species list, and criteria for removing a species from the list once its population has recovered; whether restrictions on land development constitute a "taking" of land by the government; the related question of whether private landowners should be compensated for the loss of use of their land; and obtaining reasonable exceptions to protection laws.
Being listed as an endangered species can have negative effect since it could make a species more desirable for collectors and poachers. This effect is potentially reduce-able, such as in China where commercially farmed turtles may be reducing some of the pressure to poach endangered species. Another problem with listing species is its effect of inciting the use of the "shoot, shovel, and shut-up" method of clearing endangered species from an area of land. Some landowners currently may perceive a diminution in value for their land after finding an endangered animal on it. They have allegedly opted to silently kill and bury the animals or destroy habitat, thus removing the problem from their land, but at the same time further reducing the population of an endangered species. The effectiveness of the Endangered Species Act, which coined the term "endangered species", has been questioned by business advocacy groups and their publications, but is nevertheless widely recognized as an effective recovery tool by wildlife scientists who work with the species. Nineteen species have been delisted and recovered and 93% of listed species have a recovering or stable population.
Captive breeding programsEdit
In many cases, captive breeding programs have been successful in restoring endangered species population.
- Endangered Species & Wetlands Report Independent print and online newsletter covering the ESA, wetlands and regulatory takings.
- Everything you wanted to know about endangered species — Provided by New Scientist.
- Endangered species charted by number of species and risk of extinction.