The 1972 ban on DDT was the single most important factor in the revival of the bald eagle. Being listed as an endangered species gave the birds additional protection. Bald eagle populations are now carefully monitored, and baby eagles are raised under human protection later to be released into the wild. Thank to these to these efforts, the number of eagles in the United States has grown markedly and the birds can be seen in many national parks. In August 2007, bald eagles were removed from the ESA list.