Why were peregrine falcons endangered?
During the mid-1900s a chemical pesticide called DDT was widely used to prevent insect damage to crops. DDT worked its way up the food chain when poisoned insects were eaten by smaller birds that were then eaten by larger birds including peregrine falcons. The DDT built up in the fat tissues of the falcons. This caused the falcon eggshells to be so thin that they would break when the adults would try to incubate them. This resulted in few new falcons being added to the population. Consequently, the population disappeared east of the Mississippi by 1965. Success of the Eastern Peregrine Recovery Plan in recent years has helped restore populations of the peregrine falcon.
