Bald eagles are endangered because humans have contaminated the bald eagle's food through poisonous chemicals such as DDT, destroyed their habitat areas and shot them illegally. The bald eagle is the national symbol for the United States, so the American government decided to enact the Endangered Species Act to protect the bird.
In 1972, the chemical DDT was restricted in many areas, allowing bald eagles to reproduce fully once again without trouble. DDT had caused problems for the bald eagle because it altered the bird's nervous system. It caused female eagles to be unable to reproduce and when they did reproduce, the insecticide would often cause infertile eggs. The DDT created an abundance of calcium in the eggshells too, which led to brittle eggs that easily snapped when delivered.
In 2007, the bald eagle population in the United States reached a level that brought it down from the "endangered" list to the "threatened" list, so scientists are hopeful for the growth of the species. The bald eagle is also protected under the Bald and Golden Eagle Act as well as the Migratory Bird Treaty Act.
The bald eagles have to build their nests near marshes, rivers and lakes where they can easily hunt for fish. Although the bald eagle eats turtles, snakes, waterfowl and rabbits, they base their diet around fish.