Wild in the City: Chicagoland's Urban Ecology

Species Reintroduction

Just as study of birds killed by window impacts, such as the Common Yellowthroat, helps determine ways to reduce the number of window collisions during seasonal migrations, research using the Chicago Academy of Sciences' varied scientific collections has helped combat broader issues such as habitat loss, concentrations of pesticides in the environment, and other factors leading to population declines among different species in the Chicago region. One of the more dramatic stories of species reintroduction is that of Peregrine Falcons. As with many birds of prey species, Peregrine Falcons suffered severe population declines starting in the late 1940s because of widespread pesticide use and habitat loss across North America. The last known breeding pair in Illinois occurred in Jackson County in 1951; in 1970, Peregrine Falcons were listed as a federally endangered species in the United States. Scientists studying Peregrine eggs in scientific collections identified significant changes in egg strength resulting in egg thinning and nest failure, and pinpointed the cause as a result of ingesting poisons, such as the pesticide DDT, from the animals the falcons ate.

In 1985, the Chicago Academy of Sciences, Lincoln Park Zoo, Illinois Department of Conservation, and Chicago Audubon Society initiated the Peregrine Falcon Release and Restoration Project to re-establish the Peregrine Falcon population in the Chicago area as part of wider reintroductions throughout the nation. The first Peregrines were released in 1986, just one year after the project started. Scientists closely monitored the falcons. The first successful nesting in Chicago was documented in 1988—the first in Illinois in 37 years. Although Peregrine Falcons did not originally have large populations in the Chicago region, the city’s tall buildings have served as a suitable habitat as they mimic the high perches the birds seek. Peregrine Falcon populations have stabilized locally and nationally, and in 1999 were delisted federally as a result of their recovery.  Mary Hennen, who worked with the restoration project at the Academy from 1985 to 1995, is now based out of the Field Museum where she continues to monitor the Peregrine Falcon population in the Chicago area and oversees the Peregrine Falcon Program.

Use the cards at the bottom of each page to explore various parts of the "Documenting Urban Nature" chapter. There will always be a card to take you back to the chapter introduction or you can go back to the Wild in the City overview.

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