Bald eagles were very negatively affected by DDT, a pesticide that was not banned in the US until 1972 though its dangers were known in the early 1960s. It wasn’t lethal to the bald eagles themselves, but the DDT they ingested weakened the shells of their eggs to the point where the eggs cracked under the weight of an adult eagle.
Thanks to the banning of DDT in 1972 and the passage of the landmark Endangered Species Act  in 1973, this colossal bird of prey recovered at a faster pace than conservationists had ever expected. Today, illegal shooting of bald eagles is considered the biggest threat to their survival. Other threats include lead poisoning from eating ducks that have consumed lead shot, power line electrocution and habitat loss.
Reasons for Hope
The bald eagle has made a tremendous recovery over the past several decades thanks largely to the Endangered Species Act (ESA). In June of 2007, the U.S. Fish & Wildlife Service announced the removal of the bald eagle from the list of species protected by the Endangered Species Act. The Fish and Wildlife Service will monitor bald eagles for a 5-year period as required by the Endangered Species Act. The announcement marked a successful milestone in the species’ recovery from the brink of extinction.