Welcome to brain Stuff from How Stuff Works. Hey, I'm Lauren vocal bam. This is brain stuff, and I have a topically relevant scenario for your consideration. Let's say you want a change of scenery, so you set out with the clothes on your back, your innate knowledge of the world, and zip all else. Would you be able to travel a few thousand miles and wind up somewhere with excellent food options and potentially attractive members of your species? And then would you be able to get back home a
few months later? I personally would be hopelessly lost within a week, and yes, I would be completely useless during a zombie apocalypse. But lots of birds do this every year. Migration can take birds tens of thousands of miles across oceans and continents, and often to the exact same summer and winter spots, using nearly the exact same roots every time.
It's not like they have a GPS. Ornithologists have speculated that birds might use a number of audio, visual, odorous, and learned social cues to get where they're going, but young birds making their trip for the very first time have been observed to migrate successfully with no chaperones, so assuming that birds aren't feathered cyber drones hacking our global positioning satellites? What gives how to birds migrate? Research has
revealed that migratory birds have vision based magneto reception. They can see magnetic fields, and Earth is lousy with magnetic fields. The primary one is what makes compasses work. These magnetic fields exist because Earth's molten outer core is made up of iron alloys, which are switched around by heat coming up off of these solid intercore and by the rotation of the Earth. That motion, plus the fact that iron
is really good at conducting electricity, create a dynamo. A dynamo being a generator of electric and magnetic fields, which basically makes Earth function like a giant bar magnet. The north pole is positive, the south pole is negative, and our planet is wrapped in magnetic fields arking between them in slopes and curves, and migratory birds can sense those fields.
Experiments over the past couple of decades have shown that birds prepared to migrate south will align themselves with magnetic self even in the lab if you create an artificial magnetic self. Furthermore, these birds actually see magnetic fields around. Researchers fit European robins with either clear or frosted goggles, and they found that the birds needed clear vision in
their right eyes, specifically in order to navigate magnetically. Now scientists are studying what biological mechanism might be responsible for this. More research needs to be done, but the popular theory goes that magnetic fields cause a chemical reaction in birds eyes that affect their sensitivity to light, so magnetic fields might show up as brighter or darker patterns spread out over everything that the bird sees. It's sort of like a map on a heads up display. Today's episode was
written by me and produced by Tyler Clang. If you like our show and also like not being naked, check out our online store at t public dot com slash brain stuff, and of course, for more on this and lots of other bird brained topics, by which I mean very interesting ones, visit our home planet, how stuff works dot com