Endangered species

According to the International Union for Conservation of Nature and Natural Resources (IUCN), the foremost authority on species conservation status, in 2024, over 45,00 species of plants, fungi, and animals worldwide were considered threatened with extinction (meaning their conservation status is vulnerable, endangered, or critically endangered, according to IUCN categories). In 2022, BirdLife International announced that about half of the world's bird species were in decline, with roughly one-eighth of all known living species threatened with extinction. Amphibians are among the most immediately threatened types of animals.

Causes of Species Endangerment

The destruction of species is caused in four major ways: humans hunting other species out of existence; habitats, the environments in which organisms grow and develop, being destroyed; new species, such as rats, cats, goats, or ground-covering plants, being introduced into regions and displacing native species; and nonnative plants and animals introducing diseases into environments, killing the existing species. For much of history, hunting was the major cause of species extinction. However, hunting has become less of a factor since governments and conservation authorities have imposed strict controls on the practice. In the second half of the twentieth century, habitat destruction and invasion by exotics (nonnative plants and animals) and the diseases they carry caused the most damage. Most biologists agree that whatever the factors involved, the rate of extinction has increased rapidly since the 1950s.

Some people have argued that the destruction of a single species of fish, bird, or flower would make little or no difference to the future of human life or the earth. They also suggest that extinctions have always taken place, even before human beings existed, and therefore are simply part of the natural process of existence. These arguments omit an important point. Individual species each inhabit a small part of an entire ecosystem, a community of plants and animals that are closely associated in a chain of survival. For example, plants absorb from the soil chemicals and minerals that are essential to their health. Herbivorous and omnivorous animals then eat the plants—grasses, fruits, leaves, or flowers—and digest the nutrients they need for energy. Carnivorous and omnivorous animals then eat the plant eaters and get their energy from them. If a single species is removed from this chain, the whole ecosystem can suffer unknown and perhaps terrible consequences.

The death of an entire species constitutes a loss that cannot always be measured in economic terms. The American biologist William Beebe made the point that any species that is lost diminishes the quality of life for everyone:

The beauty and genius of a work of art may be reconceived, though its first material expression can be destroyed; a vanished harmony may yet inspire the composer, but when the last individual of a race of living things breathes no more, another heaven and another earth must pass before such a one can be again.

How Species Are Lost

Deaths of entire species grew more frequent in the 1900s. One example of this loss was the passenger pigeon, a bird so numerous in the 1820s that flocks numbered in the hundreds of millions, and John James Audubon, the famous American painter and collector, wrote that the flapping of wings on the Great Plains sounded like the roar of thunder. More than nine billion of the pigeons were alive in 1850; slightly more than sixty years later, exactly one bird, named Martha, remained—in the Cincinnati Zoo, where she had been taken in 1912. The population fell from nine billion to one in little more than half a century, then to zero when Martha died on September 1, 1917. People had found these pigeons delicious to eat and easy to kill. They formed hundreds of hunting parties, killing more than fifty thousand birds each week. No one dreamed that the passenger pigeon could ever be exterminated.

The same fate almost befell the American bison, often called the buffalo. Before the coming of railroads and White settlers in the 1860s and 1870s, the bison numbered more than one hundred million. American Indians hunted the bison, eating their flesh and using the skins for clothing and shelter, but they killed only what they needed. The settlers, however, saw the bison as a problem that needed to be solved. Huge herds of bison crossed railroad tracks, forcing passenger trains to stop, and the animals interfered with farming, knocking down fences and trampling grain fields. Railroad companies and the US Army sent out hunting parties to get rid of the bison. By 1890, fewer than one thousand bison survived in a herd that had managed to escape far into northern Canada. The extermination ended only after this small herd was given protection by the Canadian government.

Stories of other near-extinctions are numerous and frightening but demonstrate that action can be taken to save some, if not all, of the endangered species. Whales, which had been hunted since the 1600s, faced possible extinction until action was taken to reduce hunting in the 1970s. Whales were easy to kill and provided oil and bone. Whale oil was the major substance burned in lamps until the electric light largely replaced oil-burning lamps in the 1880s. Europeans hunted the North Atlantic whale, called the right whale because it was the “right” one to kill, into virtual extinction by the 1860s. When the North Atlantic right whale became too hard to find, hunters turned to the Pacific right whale and then the bowhead whale before action was taken by the world community to save remaining whales.

Human greed has brought death or near death to many species. The desire for fur coats has killed nearly all jaguars, snow leopards, and various species of fur seals. Pribilof Island fur seals were hunted nearly into extinction in the late 1800s. A treaty between the United States, Canada, and Russia established limits on killing the species in its remote northern Pacific island habitat, but enforcement has proved difficult, and thousands of seals have been slaughtered despite international protection.

The belief that some animals are nuisances has led to the near extinction of wolves, grizzly bears, cougars, and coyotes. These predators have been poisoned and shot by the thousands and have become endangered species as a result. Attempts to kill insects with pesticides to control the spread of disease and improve crop yields were successful but had an unfortunate side effect: chemicals from the pesticides worked their way into ecosystems, killing millions of other forms of life. In the 1950s, dichlorodiphenyltrichloroethane, or DDT, was used to kill malaria-carrying mosquitoes, but the chemical affected the entire food chain. It entered plants that were eaten by birds, fish, and butterflies, among other animals. Pesticide poisoning also diminished the numbers of the bald eagle and peregrine falcon, which started to come back only after rigid controls on pesticides were established.

Events on the island of Madagascar, a large island in the Indian Ocean off the east coast of Africa, demonstrate most fully the deadly consequences of habitat destruction. About 180 million years ago, the island was attached to the African continent; then it was split off after a series of geological catastrophes and ended up 250 miles to the east. The split occurred just at the time mammals were emerging as a class of animals in Africa. One mammal species, the monkeylike lemur, became isolated on Madagascar and increased abundantly. Other animals caught on the island were several kinds of giant birds, including one that weighed a thousand pounds and stood ten feet tall. The island was isolated for millions of years, allowing hundreds of species found nowhere else in the world to evolve in the diverse island ecosystems. Madagascar had deserts, rain forests, dry forests, and seashores. About 99 percent of its reptiles, 81 percent of its plants, and 99 percent of its frogs were unique and tied specifically to the island’s food chain. About two thousand years ago, the Malagasy people began to arrive on the island. They hunted, fished, and began to grow crops, destroying more than 90 percent of the forests that covered Madagascar in the process. Dozens of species died as a result, including the giant elephant bird, which was gone by 1700. Ten out of thirty-one species of lemur had died out by 1985. The loss of Madagascar’s forests caused terrible erosion, which resulted in flooding and the destruction of more trees. Madagascar’s entire ecological system thus became threatened, and by the early 2020s, more than 360 unique species were listed as endangered.

The United States’ Endangered Species Preservation Act

The implications of species and habitat destruction were first described in books such as biologist Rachel Carson’s Silent Spring (1962), about the effects of DDT and insecticides on birds and other animals. Her book inspired Congress to pass the Endangered Species Preservation Act in 1966, protecting certain fish and wildlife through the creation of the National Wildlife Refuge System. Congress strengthened the law in 1969 by restricting importation of threatened species and adding more domestic species to the list of those deserving protection.

The US Department of the Interior published its first list of endangered species in 1967. The list included seventy-two native species of animals, including grizzly bears, certain butterflies, bats, crocodiles, and trout, but no plants. In 1973, President Richard M. Nixon signed into law the Endangered Species Act (ESA), which gave the secretaries of the interior and of commerce responsibility for creating a list of endangered animals and plants, or species in immediate danger of extinction. Another list would include species threatened with extinction or those likely to become endangered in the foreseeable future. Once a species was on either list, no one could kill, capture, or harm it. Penalties for violators were increased, and international or interstate trade of listed species was prohibited. Fines of up to ten thousand dollars could be imposed for knowingly violating the act, while a person could be fined up to one thousand dollars for unwittingly violating it.

A separate provision mandated that federal agencies could not engage in projects that would destroy or modify a habitat critical to the survival of a threatened or endangered plant or animal. This provision became a crucial tool to save species. Supporters of wildlife preservation used it to block highway and dam projects, at least until government officials could prove that construction would have no major impact on a fragile ecosystem. The law even called for affirmative measures to aid in the recovery of listed species. The secretaries of the interior and commerce were required to produce recovery plans detailing steps necessary to bring a species back to a point where it no longer needed protection. Money was appropriated for states to design recovery programs, and most states established plans of their own to deal with local crises.

A major threat to the 1973 law arose in 1978 during the Tellico Dam controversy. The federally owned Tennessee Valley Authority proposed building a hydroelectric dam on the Tennessee River in Loudon County, Tennessee, in the late 1970s. Shortly after plans were made public, a University of Tennessee scientist discovered a three-inch-long fish, the snail darter, that was unique to the area. Building the dam, a $250 million project, would destroy the snail darter’s habitat and eliminate the fish. Environmentalists successfully argued in federal court that the dam had to be abandoned, and the US Supreme Court upheld the ruling, arguing that when Congress passed the law, it had intended that endangered species be given the highest priority regardless of the cost or other concerns involved. However, in 1981, Congress enacted a special exemption that excluded “economically important” federal projects from the act. A federal judge then found the Tellico Dam lacked economic importance, and construction was again halted. Legislators friendly to dam interests then added an amendment directing completion of the dam to an unrelated environmental bill, which passed, and Tellico was constructed. However, the principle of protection remained intact, and the 1973 act remained in force. The snail darter apparently survived, too, as scientists found it living in a river not far from the spot where it was originally discovered.

In August 2019, under the administration of Donald Trump, the US Department of the Interior's Fish and Wildlife Service and the US Commerce Department's National Marine Fisheries Service jointly changed sections 4 and 7 of the ESA. Specifically, these changes clarified that the standards for listing, delisting, and classification of a species consider the same statutory factors; added economic impact as a criterion during protection deliberations; raised the standard for critical habitat designation to only those containing one or more physical or biological features necessary for conservation of the species; clarified the consultation process and alternative consultation mechanisms; set a deadline for informal consultations; and revised definitions of “destruction or adverse modification,” “effects of the action,” and “environmental baseline.” The FWS also separately rescinded its so-called blanket rule that automatically gave endangered-species protections to threatened species; instead, protections could be extended case by case.

However, a coalition of environmental groups called for the overhaul to be rescinded and sued the administration; in 2022, a federal judge overturned the Trump-era amendments to the ESA, restoring comprehensive federal protections of endangered species. In 2024 the administration of President Joe Biden restored the blanket rule and eliminated the economic impact criterion from listing decisions. Significantly, it also recognized climate change as one of the major factors imperiling species' survival.

International Trade Bans

The 1973 act also made the United States a partner in the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). This treaty came out of a conference in Washington, DC, that was attended by representatives from eighty nations. It created an international system for control of trade in endangered species. Enforced by the Switzerland-based International Union for the Conservation of Nature and Natural Resources (IUCN), later simply the International Union for Conservation of Nature, the convention has 184 members. The IUCN maintains the IUCN Red List of Threatened Species, which sorts species into one of nine categories: extinct, extinct in the wild, critically endangered, endangered, vulnerable, near threatened, least concern, data deficient, and not evaluated. Category 1 consists of those in immediate danger and therefore absolutely banned from international hunting and trading. Animals and plants in categories 2 and 3 are not immediately threatened but require special export permits before they can be bought and sold because their numbers have been seriously reduced.

CITES has a major flaw, a loophole that can be exploited by any member: any nation can make a “reservation” on any listed species, exempting itself from the ban on trade. Japan has been among the most frequent users of the reservation, exempting itself from controls on, among others, the fin whale, the sei whale, the scalloped hammerhead, and the squat-headed hammerhead, all designated endangered by the IUCN. Other frequent offenders include Canada and Iceland. As the loophole remained open in the twenty-first century, the IUCN remained severely restricted in its ability to save threatened species.

Successes in Restoring Endangered Species

More than one hundred species—including the California condor, the black-footed ferret, and the whooping crane—have been saved from extinction because of the ESA. The road to extinction has also been reversed for the brown pelican, found in the southeastern states; the American alligator, which had been hunted almost to death in Florida; and the peregrine falcon in the eastern US. By 2023, at least twenty-one species, however, had totally disappeared, while others, such as a bird called the Guam rail, had been declared extinct in the wild.

The northern spotted owl, found in parts of the rainforest in Oregon and Washington, attracted a good deal of attention because of efforts to save it. The case of the owl points to the most difficult questions raised by the act: Which comes first, the welfare of the plant or animal or the economic needs of people? Each pair of spotted owls needs six to ten square miles of forest more than 250 years old in which to hunt and breed. The owls also need large hollow trees for nesting and large open fields in which to search for mice and other small animals. Most of the suitable ecosystems are found in parts of twelve national forests in the region. At the same time, loggers in the areas need jobs. When the interests of the lumber industry and environmentalists collide, it is left to the courts to determine which interest will prevail or whether a compromise can be arranged.

Outside the United States, the future of endangered species appeared much grimmer, despite some success. In 2024, the IUCN marked the significant recovery of the Mediterranean region's Iberian lynx, which had gone from 62 mature individuals in 2001 to over 2,000 at that point. Still, scientists warned that extinctions were accelerating at concerning rates, driven by the expansion of agriculture, forest destruction, and climate change, among other human-made problems. Many of these species have never even been identified or named. The most endangered habitats in the world are the tropical rainforests, which were reduced by half—nearly 3.5 million square miles—during the twentieth century. Over fifty thousand square miles are destroyed each year, mainly to provide farms and cattle ranches. Among the most threatened animal species in these forests are primates, including various species of capuchins, spider monkeys, lemurs, and macaques, as well as the western gorilla. One solution to forest destruction has been the creation of large wildlife refuges, but the amount of land available for conservation efforts is limited and such efforts have displaced indigenous peoples and interfered with their lifeways too. Another solution is the establishment of more wildlife zoos. Several zoos have successful programs for saving species on the very edge of extinction. However, capacity is limited, and the very small numbers of animals in a zoo’s herd create problems of interbreeding and the handing down of recessive genes.

For many species, it is too late to do very much, so scientists and biologists divide populations into three groups: those that can survive without help, those that would die whatever help was provided, and those species that might survive with help and would certainly die without it. Environmentalists focus their efforts on the plants and animals that fall into the third category. Resources proved limited, however, and activists asserted that much work needed to be done, or extinctions would take place at a pace as yet unseen in the history of living things.

Principal Terms

ecosystem: a biological community and the physical environment contained in it

environment: the physical, chemical, and biological conditions of the region in which a plant or animal lives

extinction: the complete destruction of a species

habitat: the place in which a plant or animal lives

species: a group of similar individuals that can breed among themselves and produce offspring

Bibliography

Boyles, Kristen L., et al. Center for Biological Diversity et al. v. Bernhardt et al. Case No. 3:19-cv-05206, US District Court for the Northern District of California, San Francisco Division, 21, Aug. 2019, cdn.cnn.com/cnn/2019/images/08/21/2019-08-21.lawsuit.complaint.challenging.endangered.species.act..pdf. Accessed 22 May 2024.

DiSilvestro, Roger L. The Endangered Kingdom: The Struggle to Save America’s Wildlife. Wiley, 1989.

Doub, J. Peyton. The Endangered Species Act: History, Implementation, Successes, and Controversies. CRC, 2013.

“Endangered Species.” US Fish and Wildlife Service. Department of the Interior, www.fws.gov/endangered. Accessed 5 Aug. 2024.

“Endangered Species Act Rollbacks Reversed after Animal Legal Defense Fund Lawsuit.” Animal Legal Defense Fund, 8 July 2022, aldf.org/article/endangered-species-act-rollbacks-reversed-after-animal-legal-defense-fund-lawsuit/. Accessed 22 May 2024.

Friedman, Lisa. “U.S. Significantly Weakens Endangered Species Act.” The New York Times, 12 Aug. 2019, www.nytimes.com/2019/08/12/climate/endangered-species-act-changes.html. Accessed 22 May 2024.

Goble, Dale D., et al. The Endangered Species Act at Thirty. 2 vols. Island, 2005–6.

The IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources, 2024, www.iucnredlist.org/. Accessed 5 Aug. 2024.

Mackay, Richard. The Atlas of Endangered Species. 3rd ed., U of California P, 2009.

Olive, Andrea. Land, Stewardship, and Legitimacy: Endangered Species Policy in Canada and the United States. U of Toronto P, 2014.

Randall, Jan A. Endangered Species: A Reference Handbook. ABC-CLIO, 2018.

"Recovery of the Iberian Lynx: A Conservation Success in Spain." IUCN, iucn.org/news/202407/recovery-iberian-lynx-conservation-success-spain. Accessed 5 Aug. 2024.

“State of the World’s Birds 2022 Paints Most Concerning Picture for Nature Yet.” BirdLife International, 28 Sept. 2022, www.birdlife.org/news/2022/09/28/state-of-the-worlds-birds-2022-paints-most-concerning-picture-for-nature-yet/. Accessed 22 May 2024.

Vié, Jean-Christophe, et al., editors. Wildlife in a Changing World: An Analysis of the 2008 IUCN Red List of Threatened Species. IUCN, 2009.

Wilson, Edward O. The Diversity of Life. Belknap, 2010.