This is bird note.

While a bird's eye view lets a migratory songbird like this European Robin

keep track of important landmarks along its route, a special protein in its eyes might let it

see Earth's magnetic field. It's like a hiker using a compass to find true north.

As European Robbins get closer to migration, their eyes produce more of a light detecting protein called a cryptochrome. Non-migratory birds have this eye

protein too, but at lower levels. To understand why migratory birds might need more of

this protein.

Scientists compared the cryptochrome proteins

from European robins, birds that do migrate,

to those from chickens and pigeons,

birds that don't migrate.

They found that only the Robin's cryptochrome changed its behavior in the presence of a weak magnetic

field.

This feature could make the bird's field of view appear darker in the direction of a magnetic field line, letting them visualize which way is north.

Pigeons do have a magnetic mineral called magnetite embedded in their beaks.

So even though they may not be able to see magnetic fields, they can detect them.

This is what makes homing pigeons so good at finding their way back home.

Birds on the move may use one or both ways of sensing magnetic fields.

For Bird Note, I'm Mark Bramhill.