Published: July 14, 2015

Peregrine Falcons Removed from IL Endangered List

Kate Golembiewski, PR and Science Communications Manager, Public Relations


Peregrine Falcons have their share of claims to fame—with a diving speed of over 200 miles per hour, they’re the fastest animals in the world, and they’ve adapted from living on rocky cliffs to a different kind of “mountain”: Chicago’s skyscrapers.  But in 1951, there were none left in Illinois, and it looked as if the species would be wiped out of North America entirely. Today, thanks largely to the Chicago Peregrine Program headed by The Field Museum’s Mary Hennen, Peregrines are flourishing to the point that they’re no longer in immediate danger. As of a few weeks ago, the species was removed from Illinois’s Endangered and Threatened Species List.

“We’re thrilled that Peregrines are doing so well, but the journey’s far from over. Now that they’re off the threatened list, in some ways, we need to work harder to make sure that they’re doing okay,” said Hennen. And even though the falcons aren’t considered threatened anymore, they’re still protected under the Migratory Bird Treaty Act.

Peregrines first became endangered in the 1960s due to eating prey contaminated with a pesticide called DDT that caused their eggshells to thin and crack under the nesting parents’ weight. The Field Museum’s egg collections played a part in getting DDT banned—scientists looked at our eggs from the turn of the century and compared them with the thinner, more brittle shell fragments to prove the link between DDT and dwindling Peregrine numbers.

Even after DDT was banned in the US in 1972, the damage was done—about 90 percent of the historic North American population had been lost. But programs throughout the country have since been helping the birds make a comeback. The Chicago Peregrine Program, founded in 1985, introduced 46 birds to the area from a captive breeding program. These birds have flourished, establishing nests throughout the state. There are now twelve breeding pairs that call the Windy City home, and every year, more Chicago Peregrines hatch.

Today, the program focuses on monitoring Illinois Peregrines.  Hennen and her team suit up in rock climbing gear to venture out onto skyscraper ledges to put identifying ID bands on falcons and check on nesting sites. They’ve even set up webcams so they—and anyone else who’s interested—can watch a live feed of the fluffy chicks. (At this point, the young Peregrines are already leaving their nests, but check back next April.)

The Chicago Peregrine Program team also helps conduct research on the falcons. They collect blood samples from the birds, which are taken back to The Field Museum’s DNA lab to see how the falcons are related to each other, and they help check the chicks for parasites.

Even if hanging out on high-rise rooftops doesn’t sound like your cup of tea, you can still help the falcons. “If you see a Peregrine in the city, take a picture of it and send it in—it’ll give us a better sense of the birds’ territories and lets us make sure that they’re doing okay,”  said Hennen. Photos or questions about Peregrine Falcon recovery can be sent to Mary at


  Photo credits   Banner: © Stephanie Ware   Inset: © Joel Pond