The passenger pigeon is now extinct. The last member of the species died in 1914. Encyclopædia Britannica, Inc.
The list of plant and animal species recognized as endangered or threatened is much too long to allow for discussion of each. Selected examples, however, serve to indicate the problems faced and solutions being applied.
The International Union for Conservation of Nature and Natural Resources (IUCN) lists about 500 bird species as endangered (or critically endangered) worldwide, and the United States Fish and Wildlife Service (FWS) lists more than 75 in the United States. Birds provide several modern examples of how extinction can occur. One of the best known is the passenger pigeon, a species said to have occurred in greater numbers than any other bird or mammal for which there are records. Passenger pigeons looked quite similar to mourning doves, a close relative that is still common. One distinction—a requirement for nesting in colonies—ultimately led to the downfall of the passenger pigeon. The birds, concentrated at nesting sites, were slaughtered for food by the millions. The extinction of the passenger pigeon is a commentary on the erroneous belief that if a species occurs in large numbers it is unnecessary to be concerned about its welfare. Although John James Audubon reported seeing more than 1 billion of these birds in Kentucky in 1813, the last member of the species died in 1914.
The ivory-billed woodpecker, the largest woodpecker to inhabit North America, was believed to be on the verge of extinction, if not already extinct. There were unconfirmed sightings of the bird in the southern United States in the late 1990s. In 2005 a team of researchers announced that the ivory-billed woodpecker had indeed been sighted in eastern Arkansas, though skepticism over the rediscovery persisted among some scientists. The species’ decline coincided with the logging of virgin forest, where it had subsisted on deadwood insects.
The passenger pigeon is now extinct. The last member of the species died in 1914. Encyclopædia Britannica, Inc.
The world’s last dusky seaside sparrow died in Florida in June 1987 because its habitat, Florida’s coastal salt marsh, was severely depleted. Among birds outside of the United States, the Philippine eagle, the Chinese crested tern, and the Siberian crane are just a few examples of species considered critically endangered.
The Philippine eagle is considered critically endangered. Encyclopædia Britannica, Inc.
According to the IUCN, nearly 200 of the world’s insect species are endangered. The FWS identifies more than 50 in the United States, including two butterfly species—the San Bruno elfin and the mission blue—whose populations have been reduced in size or eliminated because of urban development in the San Francisco area. The FWS recovery plan focuses primarily on conserving the few remaining habitats where the species occur. Threats to the species and their habitats include new urban development, herbicides that destroy plants on which the species depend, insecticides that kill butterflies as well as pests, off-road vehicles that destroy vegetation, and the introduction of nonnative plants that compete with native species required by butterflies. The recovery plan also provides for research programs designed to understand the requirements of each species so that proper habitat management decisions can be made.
The mission blue butterfly is an endangered insect. Encyclopædia Britannica, Inc.
Worldwide nearly 1,200 species of fish have been identified as threatened with extinction. Examples of fish deemed endangered include the Asian arowana, the Chinese paddlefish, and the Nassau grouper. In the United States, many species of desert fishes became extinct before protective measures were taken. Despite laws for protection, many of the desert aquatic habitats and their associated species are still in danger. Numerous conservation groups and concerned individuals are working in cooperation with the FWS to assure more lasting protection for desert fishes through land acquisition and the passage and enforcement of stricter laws.
The largetooth sawfish is among nearly 1,200 species of fish identified as threatened with extinction. Encyclopædia Britannica, Inc.
More than 1,300 species of reptiles and amphibians are recognized by the IUCN as endangered, including certain crocodiles and sea turtles. Many species have been depleted by overhunting and damage to their nesting grounds. Among the United States amphibian species listed as endangered or threatened by the FWS are the Red Hills salamander, confined to a few streamside habitats in Alabama, and the Houston toad of Texas. Listed reptile species in the United States include the desert tortoise in the Southwest, the blunt-nosed leopard lizard in California, and the eastern indigo snake in the Southeast. Outside of the United States, the Venezuelan yellow frog, the Cuban pine toad, and the Baw Baw frog of Australia number among the endangered amphibians, while endangered reptiles include the Chinese alligator and the Asian three-striped box turtle.
The Chinese alligator is an endangered reptile. Encyclopædia Britannica, Inc.
The endangered leatherback sea turtle is the largest of the living turtles. Encyclopædia Britannica, Inc.
More than 1,000 mammals of the world are threatened with extinction. These include both species of elephant, eight species of whale, and some 65 primates, as well as deer, leopards, tigers, and other large mammals whose numbers have been severely reduced by overhunting and habitat destruction. Included among United States mammals that are protected to some degree are the gray wolf, the Florida panther, and the grizzly bear.
