Bird of the Week: Bald Eagle

from Wildlife Promise

Bald eagle by Andrew Nicholson.

A bald eagle looks backwards. Photo by Andrew Nicholson.

National symbol of the United States, the bald eagle also is an extraordinary conservation success story.

Some wildlife experts estimate that when the first Europeans arrived on the continent, between 250,000 and 500,000 bald eagles occupied the country, about 100,000 of them in the Lower 48. In 1782, the large, striking raptor was declared our national symbol.

The first major decline in bald eagle numbers is thought to have occurred in the late 1800s, when large numbers of waterfowl—a primary food source for eagles—were hunted for the feather trade. Eagles were hunted as well.

Passage of the Bald Eagle Protection Act of 1940 prohibited the killing or selling of bald eagles. The act also increased public awareness of the eagle’s plight.

The situation went downhill again after World War II, when use of the pesticide DDT became common on U.S. farms. As runoff, the pesticide washed into rivers, streams and lakes and collected in the fatty tissues of fish. Many eagles feeding on contaminated fish became sterile. Others continued to reproduce, but their eggs’ shells were so weakened by a metabolite of DDT—DDE—that they cracked under the weight of incubating adults.

By 1963, only 417 nesting pairs of bald eagles survived in the Lower 48.

In 1967, the U.S. Secretary of the Interior listed bald eagles south of the 40th parallel as endangered under the Endangered Species Preservation Act of 1966. The use of DDT was banned in the United States in 1972.

Following enactment of the Endangered Species Act of 1973, the bald eagle was listed as endangered throughout the lower 48 states, except in Michigan, Minnesota, Oregon, Washington and Wisconsin, where it was designated as threatened. (The species has never been listed as threatened or endangered in Alaska; populations there have always remained stable.)

From 1973 to 1995, the eagle’s protected status provided a springboard for the species’ accelerated recovery through captive breeding programs, reintroduction efforts, law enforcement and the protection of nest sites during the breeding season.

In 1995, the bald eagle’s status was reduced from endangered to threatened. An estimated 4,712 nesting pairs occupied the Lower 48.

When the U.S. Fish and Wildlife Service first proposed removing the bald eagle from the endangered species list in 1999, the breeding population south of Alaska stood at 5,748 pairs.

In 2007, the bald eagle was removed from the endangered species list altogether. By that time, there were some 10,000 nesting pairs of bald eagles in the Lower 48, a 25-fold increase over the past four decades.

Today bald eagles can be found nearly anywhere on the continent where there is water. These powerful, acrobatic birds feed primarily on fish and waterfowl but will sometimes eat carrion as well. Humans are still the most important cause of eagle mortality.

VOICE: Surprisingly high, thin twitterings and chirps, often in stuttering series.

SOURCES: “The Bald Eagle in America,” by Rene Ebersole, National Wildlife, December/January 2005 (updated 2010) and National Wildlife Federation Field Guide to Birds of North America.

January is National Bald Eagle Watch Month! Celebrate by visiting one of these 10 eagle-watching hot spots.

Report your eagle sightings: Participate in NWF’s Wildlife Watch Program.

Help NWF protect the wild places that sustain our nation’s wildlife by symbolically adopting a bald eagle.