On August 9, 2007, the bald eagle (Haliaeetus leucocephalus) was officially removed from the list of threatened and endangered species. This remarkable achievement required many threads to come together, including the publication of a ground-breaking book, the creation of a list of endangered species, a growing political movement, and the formation of the EPA.
When the bald eagle was adopted as the national bird of the United States in 1782, there were as many as 100,000 of them soaring in the skies across the country. However, by 1940 their populations had begun to decline. The Bald Eagle Protection Act, which prohibited the eagles from being killed, sold, or kept in captivity, failed to stop the decline.
The reason for this continued decline was largely unknown, until the publication of Rachel Carson’s book Silent Spring in 1962 offered a clue. Carson warned of the effects of the pesticide DDT, which was in wide use in the U.S. at the time. She presented evidence that DDT contaminated water and the fish that lived in it. When prey birds, such as bald eagles, ate those animals, the DDT accumulated in their fatty tissues. DDT affected the strength of the birds’ eggshells. Thinner, more fragile shells would break prematurely, resulting in fewer baby eagles hatching successfully.
As environmental activism grew, Congress passed the first Environmental Protection Act in 1966. The following year, the first list of federally protected endangered species was created and included the bald eagle. Growing concern about the environment also led to the establishment of the Environmental Protection Agency in 1970. Though being on the endangered species list provided benefits such as the protection of the eagles’ nesting areas, the true turning point for the bald eagle came in 1972, when the newly formed EPA banned the use of DDT in the United States. After the banning of DDT, bald eagle populations began to recover, resulting in their delisting in 2007.
Despite dramatic success stories suchas that of the bald eagle, only about one percent of the animals on the endangered and threatened species list have recovered enough to be removed from the list. On the other hand, fewer than one percent of the animals on the list have gone extinct. Based on these numbers, do you think the list is effective? Why or why not?
The banning of the pesticide DDT was one of the main factors in the recovery of the bald eagle. What are some other chemicals that have been banned by the EPA? What factors go into making the decision to ban or restrict a chemical?
What role did the food chain play in how DDT affected bald eagles?
Term Part of Speech Definition Encyclopedic Entry DDT Noun
(dichloro-diphenyl-trichloroethane) toxic chemical used as an insecticide but illegal for most uses in the U.S. since 1972.
to remove from a list.
endangered species Noun
organism threatened with extinction.
Encyclopedic Entry: endangered species Endangered Species Act Noun
(1973) U.S. legislation that protects endangered species when they are threatened by human activity.
Environmental Protection Agency (EPA) Noun
U.S. government organization whose mission is to "protect human health and the environment."
total number of people or organisms in a particular area.
happening before the expected time.
Rachel Carson Noun
(1907-1964) American biologist and author.
threatened species Noun
organism that may soon become endangered.