Peregrine falcons in Chicago

Many know the story of the use of the harmful insecticide DDT. Throughout the mid-1900s it slowly crippled predatory bird populations. DDT was absorbed by and affected many organisms and because of its bioaccumulative properties. Birds, such as hawks, falcons, and eagles, at the top of the food chain were exposed to high levels of the substance and it affected their populations greatly. Scientific museum collections, like those of the Chicago Academy of Sciences, were used to compare the egg shells of raptors before the introduction of DDT and after its widespread use. This helped determine that the thickness of eggshells had decreased after DDT was present, contributing to a significant loss of successful broods from egg breakage, which led to the decreased raptor populations. The peregrine falcon was no exception. The peregrine falcon’s population numbers decreased throughout the country and by 1951 the last breeding pair was documented in Illinois. The peregrine falcon was listed as a federally endangered species in 1970.

In order to combat the near extinction of the peregrine falcon, the Chicago Academy of Sciences collaborated with Lincoln Park Zoo, Illinois Department of Conservation, and Chicago Audubon Society in 1985 to create the Chicago Peregrine Release Program to re-establish the peregrine falcon population in Illinois as part of wider reintroductions throughout the nation. The peregrine falcon’s natural habitat is high cliffs where they can perch high above and swoop in on prey from above. The skyscrapers in cities such as Chicago provide a similar structural advantage and are a fitting peregrine falcon habitat.

The Chicago Peregrine Falcon Release and Restoration Program, with direction from Mary Hennen (a founding leader in the program), shifted focus from releasing peregrine falcons to monitoring nesting pairs of Falcons in 1990. The program, now known as the Chicago Peregrine Program, migrated from the Chicago Academy of Sciences to the Field Museum in 1995. Due to successful reintroduction programs such as the one in Illinois, the peregrine falcon has been removed from federal (1999) and state (2014) endangered species lists. In order to continue to ensure the success of the species, the Chicago Peregrine Program continues to monitor nesting pairs, band young birds, and rehab injured birds throughout Illinois.

You can help the Chicago Peregrine Program monitor peregrine falcon populations in Illinois, keep an eye out for peregrine falcons and report them! You can also watch the newest generation of peregrines grow up here, most webcams are active April-July.