1 00:00:01,800 --> 00:00:06,800 Speaker 1: Welcome to brain Stuff, a production of iHeart Radio. Hey 2 00:00:06,800 --> 00:00:09,879 Speaker 1: brain Stuff, Lauren Voke Obam here with another classic episode 3 00:00:09,920 --> 00:00:13,280 Speaker 1: from the podcast archives. This one has to do with 4 00:00:13,320 --> 00:00:17,080 Speaker 1: a bit of animal behavior that's incredibly well observed yet 5 00:00:17,239 --> 00:00:24,440 Speaker 1: not very well understood, bird migration. Hey, I'm Lauren voke Obama. 6 00:00:24,600 --> 00:00:27,800 Speaker 1: This is brain Stuff, and I have a topically relevant 7 00:00:27,840 --> 00:00:31,360 Speaker 1: scenario for your consideration. Let's say you want a change 8 00:00:31,400 --> 00:00:33,640 Speaker 1: of scenery, so you set out with the clothes on 9 00:00:33,680 --> 00:00:36,120 Speaker 1: your back, your innate knowledge of the world, and zip 10 00:00:36,240 --> 00:00:39,400 Speaker 1: all else. Would you be able to travel a few 11 00:00:39,440 --> 00:00:43,000 Speaker 1: thousand miles and wind up somewhere with excellent food options 12 00:00:43,000 --> 00:00:46,520 Speaker 1: and potentially attractive members of your species? And then would 13 00:00:46,520 --> 00:00:48,600 Speaker 1: you be able to get back home a few months later? 14 00:00:49,560 --> 00:00:53,120 Speaker 1: I personally would be hopelessly lost within a week, and yes, 15 00:00:53,159 --> 00:00:56,320 Speaker 1: I would be completely useless during a zombie apocalypse. But 16 00:00:56,640 --> 00:00:59,800 Speaker 1: lots of birds do this every year. Migration can take 17 00:01:00,320 --> 00:01:03,720 Speaker 1: tens of thousands of miles across oceans and continents, and 18 00:01:03,800 --> 00:01:07,240 Speaker 1: often to the exact same summer and winter spots, using 19 00:01:07,319 --> 00:01:10,959 Speaker 1: nearly the exact same roots every time. It's not like 20 00:01:11,000 --> 00:01:14,640 Speaker 1: they have a GPS. Ornithologists have speculated that birds might 21 00:01:14,720 --> 00:01:18,520 Speaker 1: use a number of audio, visual, odorous, and learned social 22 00:01:18,560 --> 00:01:21,360 Speaker 1: cues to get where they're going. But young birds making 23 00:01:21,400 --> 00:01:23,759 Speaker 1: their trip for the very first time have been observed 24 00:01:23,840 --> 00:01:28,600 Speaker 1: to migrate successfully with no chaperones. So, assuming that birds 25 00:01:28,640 --> 00:01:32,399 Speaker 1: aren't feathered cyber drones hacking our global positioning satellites, what 26 00:01:32,600 --> 00:01:37,520 Speaker 1: gives how to birds migrate? Research has revealed that migratory 27 00:01:37,560 --> 00:01:41,960 Speaker 1: birds have vision based magneto reception. They can see magnetic fields, 28 00:01:41,959 --> 00:01:45,200 Speaker 1: and Earth is lousy with magnetic fields. The primary one 29 00:01:45,240 --> 00:01:49,160 Speaker 1: is what makes compasses work. These magnetic fields exist because 30 00:01:49,160 --> 00:01:52,600 Speaker 1: Earth's molten outer core is made up of iron alloys, 31 00:01:52,760 --> 00:01:55,480 Speaker 1: which are switched around by heat coming up off of 32 00:01:55,520 --> 00:01:58,880 Speaker 1: these solid intercore and by the rotation of the Earth. 33 00:01:59,480 --> 00:02:01,840 Speaker 1: That motion and a plus the fact that iron is 34 00:02:01,880 --> 00:02:06,160 Speaker 1: really good at conducting electricity, create a dynamo. A dynamo 35 00:02:06,240 --> 00:02:10,680 Speaker 1: being a generator of electric and magnetic fields, which basically 36 00:02:10,919 --> 00:02:14,720 Speaker 1: makes Earth function like a giant bar magnet. The north 37 00:02:14,760 --> 00:02:17,720 Speaker 1: pole is positive, the south pole is negative, and our 38 00:02:17,720 --> 00:02:21,080 Speaker 1: planet is wrapped in magnetic fields arking between them in 39 00:02:21,160 --> 00:02:26,119 Speaker 1: slopes and curves, and migratory birds can sense those fields. 40 00:02:26,560 --> 00:02:28,880 Speaker 1: Experiments over the past couple of decades have shown that 41 00:02:28,960 --> 00:02:32,720 Speaker 1: birds prepared to migrate south will align themselves with magnetic 42 00:02:32,800 --> 00:02:35,600 Speaker 1: self even in the lab if you create an artificial 43 00:02:35,760 --> 00:02:42,160 Speaker 1: magnetic south. Furthermore, these birds actually see magnetic fields around. 44 00:02:42,480 --> 00:02:47,360 Speaker 1: Researchers fit European robins with either clear or frosted goggles, 45 00:02:47,400 --> 00:02:49,920 Speaker 1: and they found that the birds needed clear vision in 46 00:02:49,960 --> 00:02:54,720 Speaker 1: their right eyes, specifically in order to navigate magnetically. Now 47 00:02:54,760 --> 00:02:58,520 Speaker 1: scientists are studying what biological mechanism might be responsible for this. 48 00:02:59,080 --> 00:03:01,600 Speaker 1: More research needs to be done, but the popular theory 49 00:03:01,600 --> 00:03:04,680 Speaker 1: goes that magnetic fields cause a chemical reaction in birds 50 00:03:04,720 --> 00:03:08,320 Speaker 1: eyes that affect their sensitivity to light, so magnetic fields 51 00:03:08,360 --> 00:03:11,359 Speaker 1: might show up as brighter or darker patterns spread out 52 00:03:11,400 --> 00:03:14,440 Speaker 1: over everything that the bird sees. It's sort of like 53 00:03:14,480 --> 00:03:22,560 Speaker 1: a map on a heads up display. Today's episode is 54 00:03:22,600 --> 00:03:24,680 Speaker 1: based on a video script that I wrote for how 55 00:03:24,720 --> 00:03:27,480 Speaker 1: stuff works dot Com. Brain Stuff is production of I 56 00:03:27,560 --> 00:03:29,880 Speaker 1: Heart Radio in partnership with how stuff works dot Com, 57 00:03:29,919 --> 00:03:32,880 Speaker 1: and it's produced by Tyler Klang and Ramsey Yu. Four 58 00:03:32,919 --> 00:03:35,960 Speaker 1: more podcasts from my heart Radio, visit the heart Radio app, 59 00:03:36,080 --> 00:03:38,920 Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.