The peregrine falcon (Falco peregrinus), a bird of prey in the family Falconidae, is one of the most wide-ranging birds in the world with populations in both the Eastern and Western Hemispheres. However, with extensive pesticide use, particularly DDT, beginning in the 1940s, many populations of these birds were decimated. In the United States by the 1960s, the peregrine falcon was completely extirpated from the eastern half of the country because DDT and related compounds, which are amplified in the food chain/web, caused the birds' eggshells to become thin and fragile. This led to reproductive failures, as eggs were crushed in the nest during incubation. Prior to the DDT-induced losses, there were about 400 breeding pairs of peregrine falcons in the eastern United States. In the early 1970s there were over 300 active nests in the western states, but within a single decade that number dropped to...