Quantum chemical reaction behind birds’ internal compass

Researchers have discovered a radical-pair reaction in the eyes of migrating robins that could explain how the birds use Earth’s magnetic field to navigate.

Covering up to 200miles (320km) per night, some UK robins – not all of which migrate – fly all the way to southern Spain or Portugal to spend the winter. Just as humans use compasses, these birds can sense Earth’s tiny magnetic field. But how they do this remains uncertain.