The United States in 1972 banned DDT after the pesticide thinned bald eagle eggshells and pushed the national bird toward extinction; decades later, eagle populations recovered enough to be removed from the endangered species list in 2007

A mid-20th century ecological crisis saw bald eagle populations plummet. Scientists initially focused on adult mortality, missing the true culprit: the pesticide DDT. This chemical, through its metabolite DDE, caused eggshell thinning and reproductive failure. A nationwide ban on DDT in 1972, though slow to show results, ultimately allowed the national bird’s remarkable recovery, demonstrating nature’s resilience when harmful human pressures are removed.