Bald eagle chick. Photo by Craig Koppie, USFWS
Bald eagle chick. Photo by Craig Koppie, USFWS

The bald eagle, our national symbol, was once a rare site in our country. But after years of protection and recovery efforts under the Endangered Species Act, the United States supports the largest population of breeding bald eagles since World War II. Bald eagles in the lower 48 states have climbed from an all-time low of 417 nesting pairs in 1963 to an estimated new high of 9,789 breeding pairs today.

Adult bald eagles are easily recognized by brown body, white head and tail, and large, yellow beak and eyes. Immature birds are dark brown, mottled with white. The white head and tail appears by the age of 4-5 years. Adults have a wingspan of 6-7 feet. In flight, the bald eagle has a distinctive, flat-winged profile, unlike the “V” shape of a vulture.

Bald eagles usually build their nests high up in large trees along waterways. Eagle nests tower 80-110 feet above the ground. The massive nests are often used year after year, growing to 6-8 feet wide and 4 feet deep, although some may get as deep as 10 feet. They are built of large sticks and plants with a soft, inner lining of broom sedge and pine needles.

Bald eagles usually lay one clutch of one to three eggs in late winter. The eggs hatch after 35 days. The young are flying within three months. By the fourth month, they are on their own. Like eagles elsewhere, Chesapeake Bay eagles feed primarily on fish, but also eat ducks, geese, small mammals, rodents, snakes and turtles.

Prior to the 1940s, bald eagles began to decline due to the direct killing of birds, loss of habitat and decline of prey. In 1940, the Bald Eagle Protection Act made it illegal to kill, harm, harass or possess bald eagles, alive or dead, including eggs and feathers. They began to recover but then another culprit entered the picture.

Just before WWII a pesticide, DDT, was used to control mosquitoes. Rain washed the chemical off the land and into waterways where it was absorbed by plants and animals. Fish ate the plants and animals and eagles ate the fish. Bald eagles fed on prey contaminated with the pesticide. The chemical built up in fatty tissue of female eagles preventing the formulation of calcium needed for strong eggshells. Eggs cracked during incubation and widespread reproductive failure followed.

Use of DDT was banned in the United States in 1972, but our Nation’s symbol was still in trouble. In 1973, bald eagles were listed as endangered under the Endangered Species Act throughout the lower 48 states except Michigan, Minnesota, Wisconsin, Washington and Oregon where it was listed as threatened.

Bald eagles responded to the protection afforded by the Endangered Species Act as well as several other actions. Banning DDT, preventing illegal shootings, and protecting habitat through land acquisitions and landowner agreements have all helped to bring bald eagles back. Due to this success, the Fish and Wildlife Service determined that the bald eagle no longer needs protection under the Endangered Species Act. The birds will still be afforded protections under the Migratory Bird Act and Bald and Golden Eagle Protection Act

For more information about bald eagles and their protection, visit http://www.fws.gov/migratorybirds/baldeagle.htm

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