It’s not very often you can follow along with scientists’ work. Typically you just read about it when the study results are released and someone like Scientific American breaks it down for you. But the Chicago Peregrine Program (CPP) at the Field Museum is an open book… or rather, its website is.

The peregrine falcon population all but vanished in Illinois in the 1960s, and it took a pair of eggs from the 1890s for scientists at the Field to figure out why. While researchers couldn’t find peregrines, they did find remnants of their eggs, and found a significant difference between the modern eggs and the preserved ones. The older eggs had much thicker shells than the pieces researchers found. The culprit was insecticide DDT, which leads to calcium deficiencies, creating eggs that can’t support the weight of the parent bird trying to keep them warm.

Now that researchers at the Field know the cause, they’re working to get a sustainable peregrine population back in swing. If you visit their site, you can see all the places in Illinois where scientists have reintroduced the birds and where new ones have nested on an interactive map. There are even several live cameras set up, where you can occasionally see the peregrines in action.

Mary Hennen is the director of CPP, and says while their efforts have come a long way, there’s still a lot more to do.

Hennen is also the Collections Assistant in the Field Museum’s Bird Division.