Migration

Back from our Christmas break with an interesting tidbit of scientific discovery from 2018.

Scientists believe they are a step closer to solving the mystery of how birds navigate over the enormous distances they cover when they migrate. It was originally believed that the iron in their beaks provided some kind of magnetic compass but that appears not to be the case.

Then in 2000 reseachers suggested that a protein in a bird’s eye was involved but were unable to identify the protein or its exact position in the eye. This year, researching on robins (Erithacus rubecula), which are migratory in northern Europe, they have found a magnetoreceptor protein in the eye that lets birds actually see the Earth’s magnetic fields.

It is a cryptochrome they have called cry4, and it is found in the retina. When light hits cry4 in the eye of a migrating bird, there are chemical changes that are influenced by the direction of Earth’s magnetic field; this works as a directional signal to the bird.

Migrating birds (CC0)

So the flocks of fieldfares and redwings that visit the park in the winter, migrators from central Europe, see a world that is invisible to us, their flight directed by signals we can neither hear nor see.


Header photo by Dereck Bridges (CC BY-C-ND 2.0)

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