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.

Oology, 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 eggshells were so thin they broke under the weight of the incubating parent.

The link between eggshell 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,

peregrins can still be seen zipping across the sky.

For Bird Note, I'm Michael Stein.