How Do Migrating Birds Navigate?

Birds can migrate thousands of miles and back home again with no prior knowledge or assistance thanks to their superpowered vision. Learn about magnetoreception in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
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

(00:22):
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

(00:45):
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

(01:06):
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.

(01:27):
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

(01:48):
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.

(02:09):
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,

(02:30):
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

(02:51):
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

(03:13):
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