Hunting, trapping, and poisoning to protect livestock have taken a great toll among predatory mammals and birds. Overharvesting is currently threatening species worldwide, especially food fish species such as the cod. A large number of species are threatened by introduced species, or "exotics," plants or animals that are introduced into a habitat and bring with them diseases or the ability to compete more effectively than native species. The now ubiquitous European starling, for example, purposely introduced into the United States in the 1890s, is displacing the native American bluebird and other species, and the brown tree snake, native to Australia and introduced to Guam during World War II, has preyed on native species of that island to the extent that nine bird species are now extinct. Another danger is hybridization with other species and subspecies.
Another important threat is destruction of habitat by chemical pollutants. For example, bird populations have suffered great losses because of insecticides. The chemicals they contain, such as DDT, accumulate in birds' bodies and interfere with calcium metabolism. As a result, the females lay eggs with extremely thin shells or no shells at all, so the embryos do not survive to hatching. Acid rain has destroyed the habitats of many North American fish and amphibians by lowering the pH of surface waters. It is also changing the soil chemistry and harming many tree species.
Most serious of all, the destruction of physical habitat—by the drainage and filling of swamps and marshes, by the damming of rivers, by the leveling of forests for residential and industrial development, by strip mining, and by oil spills and water pollution—has left many creatures with literally no room in which to live and breed. For example, only 5% of the original forests in the 48 coterminous states, i.e., those forests that were present at the time of the first European settlement, are still standing.
Many local, national, and international organizations, such as Greenpeace, the Sierra Club, and the National Audubon Society, work to preserve habitats and heighten public awareness. Conservationists have pressed for habitat preservation through the establishment of new wildlife refuges and wilderness areas and for public and private land-use planning that would provide for development without habitat destruction. Some wildlife conservation organizations try to keep seriously endangered species viable with captive breeding programs, releasing new offspring into the species' native habitat when breeding is successful.
U.S. legislation affecting endangered species includes the various federal antipollution laws, the banning of DDT, the National Environmental Policy Act (NEPA) of 1969, and the Endangered Species Acts of 1966, 1969, 1973, 1978, 1982, and 1988. The landmark 1973 Endangered Species Act prohibits any trade in endangered species or their products and requires that federal agencies assess the impact on wildlife habitat of proposed projects—much as NEPA requires an environmental impact statement. These laws are often the only tool that conservationists have to prevent the development or other exploitation (e.g., logging or mining) of important habitats, but enforcement is also hampered by litigation and a lack of funds. Despite these problems, in the years since 1973 the status of a number of species, including the bald eagle, American alligator, and black-footed ferret, became stable or improved.
The protection of species in the United States has, however, become highly politicized. Asserting that the enforcement of environmental rules unfairly burdens business, the Republican 104th Congress prevented any further species from being added to the U.S. list of endangered and threatened wildlife and plants for 13 months from 1995 to 1996. Despite the perception that enforcement of the laws affects the economy and impedes progress, only 1% of the 50,000 projects that raised endangered-species questions between 1976 and 1986 required further investigation because of possible serious impact on a species; most of those moved forward after some modification.
On the international scene, efforts have been made to halt the trade in spotted cats and crocodiles and to curtail whaling and the taking of porpoises in tuna seines. A conference in Washington, D.C., in 1973, attended by 80 nations, drew up the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which protects more than 600 species of animals and plants. By the early 1990s some success had been achieved in banning the trade in rhinoceros horn, elephant ivory, South American parrots, bird eggs, and rare orchids, but poaching—for the high profits that can sometimes be gained from these items—continues to be a serious threat. In addition to CITES, the 1992 United Nations Conference on Environment and Development (the "Earth Summit") produced an agreement to stem the depletion of the world's diverse species (see biological diversity). See also conservation of natural resources.
See T. B. Allen, Vanishing Wildlife of North America (1974); L. Regenstein, The Politics of Extinction (1979); S. Boyd, Endangered Species (1989); E. O. Wilson, The Diversity of Life (1992); D. Ackerman, The Rarest of the Rare (1996); D. Quammen, The Song of the Dodo (1996); and the Red Data Books published by the International Union for the Conservation of Nature.
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, 190 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 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:
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.
In the United States alone, the “number of known species threatened with extinction is ten times higher than the number protected under the Endangered Species Act” (Wilcove & Master, 2008, p. 414). The US Fish and Wildlife Service as well as the National Marine Fisheries Service are held responsible for classifying and protecting endangered species, yet, adding a particular species to the list is a long, controversial process and in reality it represents only a fraction of imperiled plant and animal life (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.
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 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, which means numerous species are inching closer and closer toward extinction.
Even in the search to learn more about these species, many ecologists do not take into consideration the impact they leave on the environment and its inhabitants. It is apparent that the “quest for ecological knowledge, which is so critical for informing efforts to understand and conserve Earth’s biodiversity along with valued ecosystem goods and services, frequently raises complex ethical questions”, and there is no clear way to identify and resolve these issues. Environmentalists tend to focus on the whole ecological sphere instead of the welfare of individual animals. Focusing on such a broad view tends to diminish the value of each individual creature. “Biodiversity conservation is currently a principle goal for resource management of 11.5% of the world’s surface area.” Large portions of life occur outside these protected areas and must be taken into consideration if the conservation of endangered species is going to be effective.
In order to conserve the biodiversity of the planet, one must take into consideration the reasons why so many species are becoming endangered. “Habitat loss is the most widespread cause of species endangerment in the U.S., affecting 85% of imperiled species” (Wilcove & Master, 2008, p. 416). When an animal’s ecosystem is not maintained, they lose their home and are either forced to adapt to new surroundings or perish. Pollution is another factor that causes many species to become endangered, especially a large proportion of aquatic life. Also, overexploitation, disease (Wilcove & Master, 2008, p. 416), and climate change (Kotiaho et al., 2005, p. 1963) have led to the endangerment of several species. However, the most important factor leading to the endangerment of the majority of wildlife in the world is the human impact on the species and their environment. “As human use of resources, energy, and space intensified over the past few centuries, the diversity of life has been substantially diminished in most parts of the world” (Ishwaran & Erdelen, 2006, p.179). Basically, as the human impact on the environment increases, the diversity of life decreases. Humans are constantly using the resources and space of other species for themselves, negatively impacting the survival rate of many creatures. Humans have also set standards for which species they think should be saved and which species they find unimportant. For example, the coqui frog in Hawaii is so common that its “nocturnal singing” reduces the value of homes and prevents hotels from using rooms near forests. Hawaiians have proposed eliminating the frog, and several wildlife managers want to release a pathogen to kill the frogs (Minteer & Collins, 2005, p. 333). This example of the coqui frog demonstrates how humans have no consideration for the life of another species, and are more concerned about their own contentment and personal gain. The frog decreased the value of homes and lost business for several hotels, so the Hawaiians figured it was acceptable to get rid of the group of coqui frog living near them, without taking into consideration the environmental impact of destroying the species. Another example where the human impact affected the welfare of a species was in the instance of non-native mute swans establishing themselves at Arrowhead Lake in Vermont. When the population of swans grew to eight birds, the Vermont Fish and Wildlife Department decided to kill take action. Two swans were eventually killed, angering animal welfare organizations and people living near the lake (Minteer & Collins, 2005, p. 333). The case of the Arrowhead Lake swans demonstrates what one considers the natural environment based on human assumptions. Simply because the swans were not normally living there does not mean it is not part of their natural habitat, and there is certainly no reason for them to be destroyed because of human dissatisfaction. Yet another example of the human impact in the lives of endangered species is that of the Preble’s meadow jumping mouse. Research has shown that the mouse is not taxonomically different from the Bear Lodge meadow jumping mouse and the US Fish and Wildlife Service has proposed removing the Preble’s mouse from the endangered species list based on this information (Minteer & Collins, 2005, p. 333). This example brings into consideration the role of science in determining the maintenance of a species. It brings into questions whether scientific evidence should be the only resource used to support conservation of biodiversity. A final example of the human impact on existing species is the issue of toe clipping in ecological research. While ecologists are doing research on different species to advance their knowledge of methods of conservation, they must take into consideration the impact they have on the wildlife they are studying. Toe clipping “has been reported to result in a number of adverse effects on the animals, including inflammation and infection of the feet and limbs” (Minteer & Collins, 2005, p. 334). This example demonstrates how humans must take into consideration the wellbeing of the animal even before they perform research to help conserve the species. The human impact on species and their environments has many negative effects. It is important for humans to help maintain all species in the world and not deter their development.
“Diversity of life and living systems are a necessary condition for human development” (Ishwaran & Erdelen, 2006, p.179). Many question the importance of maintaining biodiversity in today’s world, where conservation efforts prove costly and time consuming. The fact is that the preservation of all species is necessary for human survival. Species should be saved for “aesthetic and moral justifications; the importance of wild species as providers of products and services essential to human welfare; the value of particular species as indicators of environmental health or as keystone species crucial to the functioning of ecosystems; and the scientific breakthroughs that have come from the study of wild organisms” (Wilcove & Master, 2008, p. 418). In other words, species serve as a source of art and entertainment, provide products such as medicine for human wellbeing, indicate the welfare of the overall environment and ecosystem, and provided research that resulted in scientific discoveries. An example of an “aesthetic justification” in conserving endangered species is that of the introduction of the gray wolf into Yellowstone National Park. The gray wolf has brought numerous amounts of tourists to the park and added to the biodiversity in the protected region (Wilcove & Master, 2008, p. 418). Another example, supporting the conservation of endangered species as providers of products for human wellbeing, is the scrub mint. It has been found that the scrub mint contains an antifungal agent and a natural insecticide (Wilcove & Master, 2008, p. 418). Also, the deterioration of the bald eagle and the peregrine falcon “alerted people to the potential health hazards associated with the widespread spraying of DDT and other persistent pesticides” (Wilcove & Master, 2008, p. 418). This serves as an example of how certain species can serve as identifiers of environmental health and protect human life as well as other species. Finally, an example of species providing for scientific discoveries is the instance of the Pacific yew which “became the source of taxol, one of the most potent anticancer compounds ever discovered” (Wilcove & Master, 2008, p. 418-419). Endangered species could prove useful to human development, maintenance of biodiversity and preservation of ecosystems. Many endangered species serve to better humanity; therefore humanity should serve to better endangered species.
It is the goal of conservationists to create and expand upon ways to preserve endangered species and maintain biodiversity. There are several ways in which one can aid in preserving the world’s species who are nearing extinction. One such way is obtaining more information on different groups of species, especially invertebrates, fungi, and marine organisms, where sufficient data is lacking. For example, to understand the causes of population declines and extinction an experiment was conducted on the butterfly population in Finland. In this analysis, the butterflies’ endangered list classification, distribution, density, larval specificity, dispersal ability, adult habitat breadth, flight period and body size were all recorded and examined to determine the threatened state of each species. It was found that the butterflies’ distribution has declined by fifty-one and a half percent, and they have a severely restricted habitat. One example of specific butterflies who have a declining distribution rate are the Frigga’s Fritillary and Grizzled Skipper, who have been affected by habitat loss due to extensive draining of the bogs where they live (Kotiaho et al., 2005, p. 1963-1967). This experiment proves that when we know the causes of endangerment, we can successfully create solutions for the management of biodiversity. Another way to help preserve endangered species is to create a new professional society dedicated to ecological ethics. This could help ecologists make ethical decisions in their research and management of biodiversity. Also, creating more awareness on environmental ethics can help encourage species preservation. “Courses in ethics for students, and training programs for ecologists and biodiversity managers” all could create environmental awareness and prevent violations of ethics in research and management (Minteer & Collins, 2005, p. 336). One final way in which one can conserve endangered species is through federal agency investments and protection enacted by the federal government. “Ecologists have proposed biological corridors, biosphere reserves, ecosystem management, and ecoregional planning as approaches to integrate biodiversity conservation and socioeconomic development at increasingly larger spatial scales” (Ishwaran & Erdelen, 2006, p.179). One example of a federal mandated conservation zone is the Northwest Hawaiian Islands Marine National Monument, the largest marine protected area in the world. The monument is essential to the preservation of underwater communities and overfished regions. Only researchers working in the area are permitted to fish, no corals may be removed, and the Department of Homeland Security will enforce restrictions on vessels passing through the waters via satellite imaging. The monument will serve as a home to an estimated seven thousand species, most of which cannot be found anywhere else in the world (Raloff, 2006, p. 92). This environmental monument demonstrates the fact that it is possible to create a safe environment for endangered species, as well as maintaining some of the world’s largest ecosystems.
This technique has been used with great success for many species for some time, with probably the oldest known such instances of captive breeding being attributed to menageries of European and Asian rulers, a case in point being the Pere David's Deer. However, captive breeding techniques are usually difficult to implement for highly mobile species like some migratory birds (eg. cranes) and fishes (eg. Hilsa). Additionally, if the captive breeding population is too small, inbreeding may occur due to a reduced gene pool; this may lead to the population lacking immunity to diseases.
Glenn, C. R. 2006. "Earth's Endangered Creatures" (Online). Accessed 9/30/2008 at http://earthsendangered.com.
Ishwaran, N., & Erdelen, W. (2005, May). Biodiversity Futures. Frontiers in Ecology and the Environment, 3(4), 179. Retrieved September 23, 2008, from http://jstor.org/stable /3868449
Kotiaho, J. S., Kaitala, V., Komonen, A., Päivinen, J. P., & Ehrlich, P. R. (2005, February 8). Predicting the Risk of Extinction from Shared Ecological Characteristics. Proceedings of the National Academy of Sciences of the United States of America, 102(6), 1963-1967. Retrieved September 24, 2008 from JSTOR database: http://www. jstor.org/stable/3374545
Minteer, B. A., & Collins, J. P. (2005, August). Why we need an “Ecological Ethics”. Frontiers in Ecology and the Environment, 3(6), 332-337. Retrieved September 22, 2008, from JSTOR database: http://www.jstor.org/stable/3868567
Raloff, J. (2006, August 5). Preserving Paradise. Science News, 170(6), 92. Retrieved September 22, 2008, from JSTOR database: http://www.jstor.org/stable/4017054
Wilcove, D. S., & Master L. L. (2008, October). How Many Endangered Species are there in the United States? Frontiers in Ecology and the Environment, 3(8), 414-420. Retrieved September 22, 2008, from JSTOR database: http://www.jstor.org/stable/ 3868674