Endangered Species

Sociopolitical actions undertaken to preserve endangered species and their natural habitats often conflict with human economic interests. In fact, efforts to protect an endangered species usually require an economic sacrifice from the very business or government that threatened the plant or animal in the first place. It is necessary, therefore, to define endangered species in terms of their aesthetic, practical, and economic value for humans. Preservation of endangered species is important and practical for a number of reasons: (1) organisms other than humans have intrinsic moral and ethical value, and a natural right to exist, (2) many plants and animals have an established economic value, as is the case of domesticated species, and exploited wildlife like deer, salmon, and trees, (3) other species, including undiscovered medicinal plants and potential agricultural species, have as-yet unknown economic value, and (4) most species play a critical role in maintaining the health and integrity of their ecosystem, and are therefore indirectly important to human welfare. Such ecological roles include nutrient cycling, pest and weed control, species population regulation, cleansing chemical and organic pollution from water and air, erosion control, production of atmospheric oxygen, and removal of atmospheric carbon dioxide.

Rates of endangerment and extinction have increased rapidly in concert with human population growth. Though accelerating habit loss and extinction rates are hallmarks of the modern biodiversity crisis, the link between human enterprise and species extinction has existed for almost 100,000 years, during which time Australia, the Americas, and the world's islands lost 74–86% of their animals larger than 97 lb (44 kg). In North and South America, the disappearance of numerous large animals, including extraordinary species like mammoths, sabre-toothed cats, giant ground sloths, and armoured glyptodonts coincided with the arrival of significant population of humans between 11,000 and 13,000 years ago. More than 700 vertebrate animals, including about 160 species of birds and 100 mammals, have become extinct since A.D. 1600.

There is no accurate estimate of the number of endangered species. A thorough census of the earth's smallest and most numerous inhabitants—insects, marine microorganisms, and plants—has yet to be conducted. Furthermore, ecologists believe that a large percentage of the earth's as-yet uncataloged biodiversity resides in equatorial rainforests. Because human development is rapidly converting their tropical forest habitat into agricultural land and settlements, these multitudinous, unnamed species of small invertebrates and tropical plants are categorically endangered. There are perhaps several million endangered species, most of which are invertebrates living in tropical forests.

The large number of recorded threatened and endangered species is particularly disturbing given the small percentage of organisms evaluated during compilation of lists. The 2000 IUCN Red List of Threatened Species lists 11,046 species of plants and animals facing imminent extinction around the world. The Red List includes approximately one in four mammal species, and one in eight bird species. Only 4% of the world's named plant species were evaluated for Red List. In the United States, where species must meet a stringent set of criteria to be listed as endangered or threatened under the ESA, the 2002 list of threatened or endangered species included 517 animal species and 745 plant species. Another 35 species had been proposed for listing, and 257 species had been suggested as candidate species.

The United States Fish and Wildlife service has been thorough in its assessment of the nation's ecological resources, but even the ESA list is incomplete. Endangered species listing favors larger, more charismatic plants and animals, especially vertebrate animals and vascular plants; endangered species of arthropods, mosses, lichens, and other less-well known groups remain undercounted. The humid Southeast and the arid Southwest have the largest numbers of endangered species in the United States. These regions tend to have unique ecological communities with many narrowly-distributed endemic species, as well as extensive human urbanization and resource development that threaten them.

There are numerous examples of endangered species. In this section, a few cases are chosen that illustrate the major causes of extinction, the socioeconomic conflicts related to protection of endangered species, and some possible successful strategies for wildlife protection and conflict resolution.