Peregrine Falcons were once wiped out along the Eastern seaboard. The culprit was DDT, a pesticide that weakened the birds’ eggshells. DDT was used from the 1940s until it was banned in 1972. Nest boxes, like those in Boston’s Custom House Tower, have been crucial to the remarkable recovery of these birds. In fact, Peregrines have bounced back particularly well in cities, including Boston, New York and Chicago.
