Field Notes: Peregrine Falcon Parents (Patreon)

Our upcoming episode follows a peregrine falcon pair, Annie and Grinnell, as they lay their eggs and raise three chicks at the top of the University of California, Berkeley’s 300-foot bell tower. Peregrine falcons are found in cities across the United States, from New York to Chicago to San Francisco. But it wasn’t always like this.

These raptors – the fastest animals in the world – were on the brink of extinction in the 1960s, after the pesticide DDT thinned their eggshells to the point where they would break when parents sat on them. Peregrine falcon eggs that had been collected for decades by museums helped scientists figure out that eggshells had been thinning out.

For our episode, our series cinematographer Josh Cassidy filmed peregrine falcon eggs in the collection of the Museum of Vertebrate Zoology, at the University of California, Berkeley. The MVZ’s collection was one of those studied to figure out the cause of the eggshell thinning, according to Carla Cicero, the museum's curator of birds.

"A lot of our specimens go back to the late 1800s, early 1900s," Cicero said. "So you have this historical material to be able to compare the  eggs before and after the introduction of DDT."

The pesticide, which was used on crops and to control mosquitoes, was introduced in the 1940s and used until it was banned in the United States in 1972.

The eggs have beautiful mottled patterns.

Photos: Josh Cassidy/KQED