An endangered species is a species whose population is so small that it is in danger of becoming extinct. Many countries have laws offering special protection to these species (forbidding hunting, banning their habitats from development, etc.) to prevent extinction. Only a few of the many truly endangered species actually make it to the lists and obtain legal protection. Many more species become extinct, or potentially will become extinct, without gaining public notice.
Many of these 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, and 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.
A listing as an endangered species can backfire, as it makes a species more valuable and more desirable for collectors and poachers.
The conservation status of a species is an indicator of the likelihood of that endangered species continuing to survive. 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 best-known worldwide conservation status listing is the IUCN Red List, but many more specialized lists exist.
The following conservation status categories are used in articles in this encyclopedia. They are loosely based on the IUCN categories.
Extinct: the last remaining member of the species had died, or is presumed to have died beyond reasonable doubt. Examples: Thylacine, Dodo.
Extinct in the wild: captive individuals survive, but there is no free-living, natural population. Examples: Dromedary, Przewalski's Horse.
Critical or critically endangered: faces an extremely high risk of extinction in the immediate future.
- Endangered: faces a very high risk of extinction in the near future.
Vulnerable: faces a high risk of extinction in the medium-term. Examples: Cheetah, Bactrian Camel
- Secure or lower risk: no immediate threat to the survival of the species.
The following lists are examples of endangered species. Note that because of varying standards for regarding a species as endangered, and the very large number of endangered species, these lists should not be regarded as comprehensive.
- Arroyo Southwestern toad (Bufo californicus (=microscaphus))
Barton Springs salamander (Eurycea sosorum)
California tiger salamander (Ambystoma californiense)
- Desert slender salamander (Batrachoseps aridus)
- Houston toad (Bufo houstonensis)
Israel painted frog (Discoglossus nigriventer)
- Italian spade-footed toad (Pelobates fuscus insubricus)
- Mississippi gopher frog ( Rana capito sevosa)
- Mountain yellow-legged frog (Rana muscosa)
Palmate newt (Triturus helvetica)
- Santa Cruz long-toed salamander (Ambystoma macrodactylum croceum)
- Shenandoah salamander (Plethodon shenandoah)
- Sonoran tiger salamander (Ambystoma tigrinum stebbinsi)
- Texas blind salamander (Eurycea rathbuni)
- Wyoming toad ( Bufo baxteri (=hemiophrys))
About 6% of the 300,000 identified species are endangered due to overcollection or destruction of habitat, among other causes. Pollinator decline is also a factor for some species.
African violet (Saintpaulia ionantha), due to forest clearance
- Baishanzu fir (Abies beshanzuensis) of southeast China, three trees known on an isolated mountain summit
Baker's larkspur (Delphinium bakeri) of California, due to very limited habitat
- Chilean wine palm (Juba chilensis), due to land clearance
- King of the Paphs Orchid (Paphiopedilum rothschildianum) of Asia, due to overcollection
- Lobster claw (Clianthus puniceus) of Australia, due to overgrazing
Louisiana Quillwort, (Isoetes louisianensis) of Louisiana, due to very limited habitat
- Madonna lily (Lilium candidum) of Europe, due to overcollection
Pinus squamata of southwest China, about 20 trees known
Saguaro cactus (Carnegia gigantea) of North America, due to overcollection, slow maturing, and slow breeding
Saharan Cypress (Cupressus dupreziana) of North Africa, due to small population and desertification