Peregrine falcons have suffered due to their position atop the food chain. One reason is that pesticides accumulate and concentrate as they travel up the food chain. Small birds and mammals might eat small amounts of pesticides. It's not enough to kill them, but it builds up in their bodies. But when a falcon eats lots of these animals, the pesticides become concentrated in the falcons. This can kill them, or make it hard to reproduce. Some pesticides (like DDT and dieldrin) reduce the birds' ability to produce strong eggshells. This makes the egg shells thin and more likely to break, which means less baby birds hatch out.

Because of pesticides and other factors, peregrine falcon populations dropped quickly and dangerously in the middle of the 20th century. All breeding pairs vanished in the eastern United States. A successful captive breeding and reintroduction program, combined with restrictions in pesticide use, has been the basis of an amazing recovery by peregrine falcons. The use of many of the most harmful chemicals is restricted in the USA. However, it is not yet restricted in Central and South American where many peregrines spend the winter. Those peregrines may still be in danger.

After having been on the endangered species list since 1969, the incredible recovery of peregrine falcons has become an example of how effective conservation measures can be. In the 1990's they were taken off the US federal list of endangered species. However, they are still listed as endangered in the state of Michigan.

IUCN Red List of Threatened Species: least concern

US Migratory Bird Act: protected

US Federal List: no special status

CITES: appendix i