Mary Hennen

I have been working in the Bird Collection in some capacity (at times student, volunteer, or staff), since 1989. Much of my time is spent with skeletal prep including managing the Bird's Dermestid colonies.

My primary work outside of the bird collection is with Peregrine Falcons (Falco peregrinus). As recently as 1960's, Peregrines had been extirpated east of the Rockies.

Many factors contributed to the decline of Peregrines, including habitat loss, hunting, and egg collecting, though the predominant cause was effects of organochlorines such as DDT. By comparing the egg shell thickness of the few remaining peregrines to historic oology collections including the Field Museum's, scientists discovered that DDT and it's byproducts interfered with calcium production in females causing them to lay thin eggs which subsequently were crushed during incubation.

With the recovery of the species, the Chicago Peregrine Program now directs it's focus towards monitoring Peregrines in Illinois. The Peregrine Falcon was removed from the Federal Endangered Species List in 2000 and has been approved for removal from the Illinois State Endangered and Threatened Species List in 2015.