BrainStuff Classics: 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 classic episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff, a production of iHeart Radio. Hey
brain Stuff, Lauren Voke Obam here with another classic episode
from the podcast archives. This one has to do with
a bit of animal behavior that's incredibly well observed yet
not very well understood, bird migration. Hey, I'm Lauren voke Obama.

(00:24):
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

(00:46):
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
tens of thousands of miles across oceans and continents, and
often to the exact same summer and winter spots, using

(01:07):
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

(01:28):
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

(01:49):
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 and a 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

(02:10):
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

(02:32):
self even in the lab if you create an artificial
magnetic south. 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

(02:54):
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 is

(03:22):
based on a video script that I wrote for how
stuff works dot Com. Brain Stuff is production of I
Heart Radio in partnership with how stuff works dot Com,
and it's produced by Tyler Klang and Ramsey Yu. Four
more podcasts from my heart Radio, visit the heart Radio app,
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