The Peregrine Falcon was once numerous throughout North America. A sharp, serious decline in the Peregrine Falcon population was noted starting in 1947.

Long-standing human interference with the birds (including the capturing of young birds for falconry and the disturbance of nesting sites) had a significant effect, but the cause of the greatest decline was determined in 1960: widespread use of pesticides. The most devastating one, DDT, was banned in Canada in 1971 and in the United States in 1972. Its prey consists primarily of other birds, from which it ingests the chemicals that have endangered the survival of the species.

This bird is one of nature's swiftest flyers and can attain dive speeds of 380 km/h (236 MPH).

Peregrine Falcons range in size from 36 to 49 cm (14 to 19 in.), and females are generally about a third larger than males.