With strong talons, notched beak, and keen eyesight, the peregrine is a well-adapted hunter. Prey, most often birds, are caught on the wing. After spotting its prey, the peregrine dives at speeds of 150 to 200 mph. The peregrine grabs prey with both feet and breaks the neck. Widespread use of pesticides led to a major decline in peregrine numbers and, eventually, to their listing as an endangered species.
Compounds accumulate in the bird as it ages and lead to difficulty in breeding.
Thinner shells also lose moisture faster and the chick dies as the egg dries out. This, combined with infertility and reported abnormal behavior during parenting, has led to many failed nesting attempts. Although DDT has been banned in the U.S. since the 1970s, it enters the chain when the peregrines prey eat grains or insects sprayed in other countries. Pairs usually begin nesting by March. The nest is made by clearing a small area in the stones or sand.