Biologists trying to restore eagle populations around the world face a difficult challenge.
When European settlers first arrived in North America, biologists estimate up to 500,000 Bald Eagles soared across its skies. But as colonies grew, people and eagles proved uneasy neighbors. Farmers complained that the eagles ate their chickens and livestock, so they paid hunters to shoot the relatively tame, slow-moving birds. Meanwhile, loggers and farmers were clearing the forests where eagles nested and the riverside trees where they liked to roost. In particular, a pesticide called DDT, used to kill lice and mosquitoes, disrupted eagle reproduction, causing female eagles to lay eggs with thin, easily broken shells.