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An endangered (EN) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as likely to become extinct. Conservation biologists use the IUCN Red List, where "endangered" is the second most severe conservation status for wild populations, following critically endangered.
3079 animals and 2655 plants are endangered worldwide, compared with 1998 levels of 1102 and 1197, respectively. The amount, population trend, and conservation status of each species can be found in the lists of organisms by population.
The conservation status of a species indicates the likelihood that it will become extinct. Many factors are considered when assessing the conservation status of a species; e.g., such statistics as the number remaining, the overall increase or decrease in the population over time, breeding success rates, or known threats. The IUCN Red List of Threatened Species is the best-known worldwide conservation status listing and ranking system.
Over 40% of species are estimated to be at risk extinction. Internationally, 199 countries have signed an accord to create Biodiversity Action Plans that will protect endangered and other threatened species. In the United States this plan is usually called a species Recovery Plan.
The IUCN Red List is far more than simply a list of threatened species; it is a system of assessing the global conservation status of species. It includes all species that have been assessed through the IUCN species assessment process and also includes species for which assessments have been attempted, but ultimately require more data to make a status determination - known as Data Deficient species. Next along the IUCN Red List spectrum are species of Least Concern and Near Threatened Species, both of which have been assessed and whose populations are relatively robust and healthy (although they may be in decline). Threatened Species refer collectively to the IUCN Red List categories of Vulnerable, Endangered, and Critically Endangered species.
The IUCN Red List 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.
IUCN categories, and some animals in those categories, include:
Under the Endangered Species Act in the United States, species may be listed as "endangered" or "threatened". The Salt Creek tiger beetle (Cicindela nevadica lincolniana) is an example of an endangered subspecies protected under the ESA. The US Fish and Wildlife Service as well as the National Marine Fisheries Service are held responsible for classifying and protecting endangered species, and adding a particular species to the list can be a long, controversial process (Wilcove & Master, 2008, p. 414).
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 uses of their lands; and obtaining reasonable exceptions to protection laws. Also lobbying from hunters and various industries like the petroleum industry, construction industry, and logging, has been an obstacle in establishing endangered species laws.
The Bush administration lifted a policy that required federal officials to consult a wildlife expert before taking actions that could damage endangered species. Under the Obama administration, this policy has been reinstated.
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 reducible, such as in China where commercially farmed turtles may be reducing some of the pressure to poach endangered species.
Another problem with the 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 in the northeastern United States have a recovering or stable population.
Currently, 1,556 known species in the world have been identified as endangered, or near extinction, and are under protection by government law (Glenn, 2006, Webpage). This approximation, however, does not take into consideration the number of species threatened with endangerment that are not included under the protection of such laws as the Endangered Species Act. According to NatureServe's global conservation status, approximately thirteen percent of vertebrates (excluding marine fish), seventeen percent of vascular plants, and six to eighteen percent of fungi are considered imperiled (Wilcove & Master, 2008, p. 415-416). Thus, in total, between seven and eighteen percent of the United States' known animals, fungi, and plants are near extinction (Wilcove & Master, 2008, p. 416). This total is substantially more than the number of species protected under the Endangered Species Act in the United States.
Over-hunting and over-fishing have been a problem ever since mankind started to hunt, and it is no different today. Animals like the bald eagle, grizzly bear, American bison, timber wolf, and sea turtles have all been hunted nearly to extinction, and these are the lucky ones. Others such as the dodo, passenger pigeon, great auk, and Stellar’s sea cows were not as lucky as they were hunted to extinction. All of these animals started off as a food source or ones almost necessary for survival, but the need turned into greed and sport and the populations of these animals were greatly depleted. A present day example of the over-hunting of a species can be seen in the oceans as populations of certain whales have been greatly reduced. Large whales like the blue whale, bowhead whale, finback whale, gray whale, sperm whale, and humpback whale are some of the eight whales which are currently still included on the Endangered Species List. Actions have been taken to try to reduce whaling and increase population sizes, including prohibiting all whaling in United States waters, the formation of the CITES treaty which protects all whales, along with the formation of the International Whaling Commission (IWC). But even though all of these movements have been put in place, countries like Japan claim that they are whaling for “scientific” purposes and continue to harvest whales. Over-hunting,climatic change and habitat loss leads in landing species in endangered species list and could mean that extinction rates could increase to a large extent in the future.
The introduction of non indigenous species to an area can disrupt the ecosystem to such an extent that native species become endangered. Such introductions may be termed alien or invasive species. In some cases the invasive species compete with the native species for food or prey on the natives. In other cases a stable ecological balance may be upset by predation or other causes leading to unexpected species decline. New species may also carry diseases to which the native species have no resistance.
Captive breeding is the process of breeding rare or endangered species in human controlled environments with restricted settings, such as wildlife preserves, zoos and other conservation facilities. Captive breeding is meant to save species from extinction and so stabilize the population of the species that it will not disappear.
This technique has worked for many species for some time, with probably the oldest known such instances of captive mating being attributed to menageries of European and Asian rulers, an example being the Père David's deer. However, captive breeding techniques are usually difficult to implement for such highly mobile species as some migratory birds (e.g. cranes) and fishes (e.g. hilsa). Additionally, if the captive breeding population is too small, then inbreeding may occur due to a reduced gene pool and reduce immunity.
Whereas poaching substantially reduces endangered animal populations, legal, for-profit, private farming does the opposite. It has substantially increased the populations of the southern black rhinoceros and southern white rhinoceros. Dr Richard Emslie, a scientific officer at the IUCN, said of such programs, "Effective law enforcement has become much easier now that the animals are largely privately owned... We have been able to bring local communities into the conservation programmes. There are increasingly strong economic incentives attached to looking after rhinos rather than simply poaching: from Eco-tourism or selling them on for a profit. So many owners are keeping them secure. The private sector has been key to helping our work."
Conservation experts view the effect of China's turtle farming on the wild turtle populations of China and South-Eastern Asia—many of which are endangered—as "poorly understood". Although they commend the gradual replacement of wild-caught turtles with farm-raised turtles in the marketplace (the percentage of farm-raised individuals in the "visible" trade grew from around 30% in 2000 to around 70% in 2007), they worry that many wild animals are caught to provide farmers with breeding stock. The conservation expert Peter Paul van Dijk noted that turtle farmers often believe that wild-caught animals are superior breeding stock; turtle farmers may therefore seek and catch the very last remaining wild specimens of some endangered turtle species.
The endangered island fox
The endangered sea otter
American bison skull heap. There were as few as 750 bison in 1890 from economic-driven overhunting.
Immature California condor
The Siberian tiger is a subspecies of tiger that is endangered