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Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, I'm

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Speaker 1: Lauren vocal bam. This is brain stuff, and I have

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Speaker 1: a topically relevant scenario for your consideration. Let's say you

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Speaker 1: want a change of scenery, so you set out with

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Speaker 1: the clothes on your back, your innate knowledge of the world,

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Speaker 1: and zip all else. Would you be able to travel

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Speaker 1: a few thousand miles and wind up somewhere with excellent

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Speaker 1: food options and potentially attractive members of your species? And

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Speaker 1: then would you be able to get back home a

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Speaker 1: few months later? I personally would be hopelessly lost within

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Speaker 1: a week, and yes, I would be completely useless during

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Speaker 1: a zombie apocalypse. But lots of birds do this every year.

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Speaker 1: Migration can take birds tens of thousands of miles across

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Speaker 1: oceans and continents, and often to the exact same summer

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Speaker 1: and winter spots, using nearly the exact same roots every time.

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Speaker 1: It's not like they have a GPS. Ornithologists have speculated

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Speaker 1: that birds might use a number of audio, visual, odorous,

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Speaker 1: and learned social cues to get where they're going, but

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Speaker 1: young birds making their trip for the very first time

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Speaker 1: have been observed to migrate successfully with no chaperones, so

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Speaker 1: assuming that birds aren't feathered cyber drones hacking our global

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Speaker 1: positioning satellites? What gives how to birds migrate? Research has

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Speaker 1: revealed that migratory birds have vision based magneto reception. They

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Speaker 1: can see magnetic fields, and Earth is lousy with magnetic fields.

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Speaker 1: The primary one is what makes compasses work. These magnetic

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Speaker 1: fields exist because Earth's molten outer core is made up

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Speaker 1: of iron alloys, which are switched around by heat coming

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Speaker 1: up off of these solid intercore and by the rotation

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Speaker 1: of the Earth. That motion, plus the fact that iron

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Speaker 1: is really good at conducting electricity, create a dynamo. A

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Speaker 1: dynamo being a generator of electric and magnetic fields, which

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Speaker 1: basically makes Earth function like a giant bar magnet. The

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Speaker 1: north pole is positive, the south pole is negative, and

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Speaker 1: our planet is wrapped in magnetic fields arking between them

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Speaker 1: in slopes and curves, and migratory birds can sense those fields.

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Speaker 1: Experiments over the past couple of decades have shown that

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Speaker 1: birds prepared to migrate south will align themselves with magnetic

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Speaker 1: self even in the lab if you create an artificial

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Speaker 1: magnetic self. Furthermore, these birds actually see magnetic fields around.

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Speaker 1: Researchers fit European robins with either clear or frosted goggles,

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Speaker 1: and they found that the birds needed clear vision in

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Speaker 1: their right eyes, specifically in order to navigate magnetically. Now

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Speaker 1: scientists are studying what biological mechanism might be responsible for this.

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Speaker 1: More research needs to be done, but the popular theory

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Speaker 1: goes that magnetic fields cause a chemical reaction in birds

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Speaker 1: eyes that affect their sensitivity to light, so magnetic fields

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Speaker 1: might show up as brighter or darker patterns spread out

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Speaker 1: over everything that the bird sees. It's sort of like

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Speaker 1: a map on a heads up display. Today's episode was

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Speaker 1: written by me and produced by Tyler Clang. If you

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Speaker 1: like our show and also like not being naked, check

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Speaker 1: out our online store at t public dot com slash

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Speaker 1: brain stuff, and of course, for more on this and

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Speaker 1: lots of other bird brained topics, by which I mean

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Speaker 1: very interesting ones, visit our home planet, how stuff works

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Speaker 1: dot com