Ornithological Mystery Solved

You are what you eat

The foods that all living things eat are made up of a variety of elements, for example carbon, hydrogen, and nitrogen. These elements get deposited in the bodies of the animals that eat them.

But not all elements are the same. There are different varieties of carbon, for example. Some carbon has an extra neutron in its nucleus and, this is the key part, the ratio of carbon with an extra neutron to normal carbon varies geographically.

The study of these different varieties of elements is called Stable Isotope Analysis.