This is Bird Note. There are 5 million bird eggs stowed away in museums across the

world. The largest egg collections are in the Natural History Museum in the

United Kingdom and the Western Foundation of Vertebrate Zoology in the United

States. O'ology, the study of eggs, gives us great insight into birds. Their

nests, the number of eggs laid, and the general nesting habitats of different

bird species. Egg shells can also offer insights into the health of birds and

our environment. In the 1950s and 60s, following the introduction of the insecticide

DDT, Peregrine Falcon populations plummeted across parts of Europe and

North America. The birds were failing to hatch eggs. Their egg shells were so thin

they broke under the weight of the incubating parent. The link between egg shell

thinning and DDT was identified using museum and personal egg collections and

this evidence helped lead to a ban on DDT. Thanks in part to some empty eggs

safely tucked away in museums. Peregrines can still be seen zipping across the

sky. For Bird Note, I'm Michael Stein.