The bald eagle has struggled against habitat destruction, shooting, and environmental degradation. Deforestation for towns, farms, and logging has robbed the eagle of much of its original habitat. Viewed as a threat to livestock, it was also killed by farmers and ranchers. By 1940, experts feared the eagle would be hunted to extinction. Congress enacted the Bald Eagle Protection Act, making it illegal to kill, harass, or possess the birds (without a permit). When DDT and other pesticides begun to be used throughout the nation, the toxic chemicals washed into rivers and lakes, where they contaminated plants and small creatures. Fish feed on these plants and animals and eagles ate the fish. They ingested a deadly dose of pesticides. The chemicals accumulated in the bird’s fat. Poisoned birds laid eggs with shells so thin that the weight of incubating parents crushed them. Eagle numbers plummeted. In the late 1950s, Rachel Carson began to investigate the use of pesticides. Her book, Silent Spring, changed the way America thought about pesticides. Scientists and government regulators came to recognize the threats that poorly controlled chemical use pose to wildlife and human health. The bald eagle’s fate warned of potential dangers to humans, other species, and the ecosystems that support them. Scientists soon revealed the link between declining eagle populations and DDT, and in 1972, the federal government banned its use. In the 1980s, the bald eagle was recovering. In 1988 that eagles were reproducing successfully enough in the wild to discontinue the federal reintroduction program. In 1995, the bald eagle exceeded 4,500 breeding pairs, and was downlisted from endangered to threaten. The bald eagle has been proposed for delisting, but has been postponed due to concerns about whether its habitat would be adequately protected without ESA protection for the bird. Its full recovery is still impeded by the presence of other contaminants and by loss of habitat from a variety of human activities.
Female bald eagles weigh up to 14 pounds and have a wingspan of up to 8 feet. Males are smaller, weighing 7- 10 pounds, and a wingspan of 6 1/2 feet. The white head and tail feathers appear only after the bird is 4 to 5 years old.
Bald eagles are found throughout the lower 48 states of the US, as well as Alaska, parts of northern Mexico, and the western Canadian provinces.
Bald eagles inhabit mature conifer forests near seacoasts, riverbanks and lakeshores.
They mate for life, laying two to three eggs yearly and building nests that they may expand year after year, sometimes producing structures 10 feet in diameter and weighing one ton. Their fidelity to mates is matched by fidelity to place, as they often nest within 100 miles of where they hatched. Eagles lay 2 to 3 eggs that are slightly larger than chicken eggs, which hatch in about 35 days.
Bald eagles prefer fish swimming close to the water’s surface, small mammals, waterfowl, wading birds, dead animal matter (carrion).