Unraveling the Monarch Butterfly Migration Mystery

Unraveling the Monarch Butterfly Migration Mystery


Oh my gosh, the trees are like made of butterflies. I knew this would be amazing, but I didn’t
know it would be this amazing. That was me, a couple of months ago, on a
mountain in central Mexico. Hey smart people, Joe here. Nearly every monarch butterfly in North America–tens
of millions of them–flies here each winter. Not gonna lie, one of the most amazing sights
I’ve ever witnessed. And it was not easy to get there. I had to fly on a plane, drive in a car, ride
a horse and hike to get up there. It’s like 10,000 feet above sea level. But all those monarch butterflies needed to
get there was their wings… Oh, and also some of the coolest frickin’
navigation biology I’ve ever heard of. Millions of tiny orange compasses with wings. Yeah, this is gonna totally change how you
look at butterflies. The
monarch butterfly migration is one of a kind. Totally unmatched in the insect world. It’s more like the migration of some birds. I mean, we’re talking distances of up to
4,500 km, each way, north and south. But there’s one big thing that makes this
migration different from what birds and other animals do: it actually takes multiple generations
of butterflies to do it. And, as you’re about to learn, that’s
what makes it so amazing. Our journey starts in spring, as monarchs
make their way north. It’s a leap-frog journey. Each generation flies, mates, lays their eggs,
and ultimately dies as it passes the baton to the next generation. A typical adult monarch only lives for two
to six weeks. So it takes 4, sometimes 5 generations to
make the trip north. The fading light of summer marks the end of
their northern migration. Shorter days and cooler temperatures prompt
female butterflies to lay a special generation of eggs. When they hatch, the caterpillars that emerge
are very different from their parents. They’ll grow up to be part of a “super
generation”. These “super generation” butterflies will
fly all the way to Mexico in a single generation. Now, most things about a monarch’s life–metamorphosis,
migrating, mating–are controlled by hormones: chemicals in their bodies that signal different
activities. “Super generation” monarchs make less
of one special hormone, and this essentially prevents them from aging. They live about 8 times longer than other
monarchs. I mean, think about that. Same species, totally different lifespan,
like one of us living past 400. This “super generation” also develops
differently as adults: They’re bigger, they can fly farther, and they can’t reproduce… which is good, because they have a heckuva
journey ahead of them. How does a bug with a brain the size of a sesame seed know it’s supposed to go to a tree, in Mexico, thousands of kilometers away? And how does it find its way to a place it’s
never been? Luckily my friend Jason was in Mexico with
me… My name’s Jason Goldman, And he is literally the perfect person to
explain it. I’m a science
journalist on the wildlife and conservation beat but before I was a journalist, I was a
scientist, and I studied animal cognition. So it’s really remarkable that these insects, with like a million neurons, brain the size of a sesame seed, can get from the northernmost parts of North America, 2000-3000 miles to these forests in Mexico, relatively accurately and relatively effectively. Absolutely blows my mind. almost every biological organism has some
kind of internal clock. In humans, our roughly 24 hour cycle tells
us when to wake up, when to go to sleep, when to eat. Monarch butterflies actually have two internal
clocks. One clock, inside their brains, is called
the circannual clock, it keeps track of annual cycles, its what tells them it’s time to
pack their bags and head south for the winter. The other clock is the key to their navigation. So there’s very few animals that we know
have a true mental map. Monarch butterflies, they don’t have a route to follow, but they do have a heading. What we do know is they have a compass in
their minds. It’s a solar compass, that tells time! Let me explain… Monarchs’ main navigation trick is reading
the horizontal position of the sun. But the sun moves from east to south to west
throughout the day. So to keep pointing yourself in one direction
relative to the sun, you also have to know what time it is. Only butterflies don’t wear wristwatches. So how do they do it? Remember earlier, how Jason said monarchs
have a second internal clock? Monarch butterflies actually have two internal
clocks. Well I always thought butterfly antennae were
just, like long, skinny noses. But these antennae do way more than just sniff. My buddy Phil Torres was down there with me,
he’s a butterfly expert, and he blew my mind when he told me this: So that antenna is telling them what time
of day it is. Then they use the information from their eyes
and the location of the sun to then orient to the right direction. Are you kidding me?! That’s incredible! That’s how humans navigated at sea for,
like, a thousand years, using advanced tools and mathematics. And these butterflies are doing it with pinhead
brains! Ok, keep it together Hanson. Let’s break this down how this sun compass
works. Say your internal clock tells you it’s mid-morning. If you’re supposed to be heading south-southwest,
then the sun should be on your left. If your antennae clock tells you it’s late
afternoon, the sun should be on your right. Special cells in their compound eyes can even
find the sun on cloudy days using polarized light. Pretty genius navigation system. Scientists have actually tested this by putting
monarch butterflies in flight simulators, and watching how they orient themselves. These monarchs spend all winter here in Mexico,
basically hibernating, living off stored energy. But as spring arrives in these mountain forests,
their internal seasonal clock tells them it’s time for the super generation to leave. And something changes in their bodies. That hormone they didn’t have, that kept
them from aging? They start making it, and they become reproductively
active. VERY reproductively active. And they begin their journey north, tracking
the sun again. Their inner sun compass somehow flips direction. Sadly… in a few short weeks, every one of
these super generation butterflies will be dead. But not before the females lay the eggs that
will become the next generation to carry on this great migration. What makes this so incredible to me it that
the butterflies that journey south are reading a map passed down from great-great-grandparents
who died half a year before they were born. It seems like it’s almost magic. But the truth is that these skills are written
into their genetics. And since the genetics get passed down generation
to generation, of course these behaviors get passed down with it. Even if each generation doesn’t need those
skills eventually one of them will take advantage of it. There’s evidence monarch butterflies have
been making this journey for millions of years. It’s an instinct. A behavior that’s built into their body. Their sun compass, their antenna clock, are
written in their genes, an unbroken chain of DNA stretching back millions of generations. But there are still more mysteries to solve. It’s not enough for the butterflies to know
where they’re going. They also need to know where they are. And we don’t know what makes them stop here,
in this Mexican forest. And if we want to solve that mystery, we need
to make sure the butterflies keep coming back… We’re on the lookout for a very special plant. Where is it? This is it, this is it right here. This is milkweed, a native milkweed. This is the plant that the butterflies need
to lay their eggs on so the caterpillars will grow up, eating, or to make the next generation,
and, if we’re lucky, yes a monarch has been here and laid an egg. Preserving the monarch migration is about
more than just preserving that forest in Mexico. It’s about preserving plants like this and
places like this. Flowers that give them nectar to fuel that
migration, it’s about protecting more than just a behavior, it’s about protecting a habitat
that stretches across an entire continent, and that’s something
that we can all play a part in. Give you something to think about maybe something
to chew on. Stay curious. That was fun, wasn’t it. Studying a migration this massive is hard. We just figured it out a few years ago, I
mean it took like half the 20th century for scientists to just figure out where they go
each year. Follow me over to the Atlas Obscura YouTube
channel, where we tell the story of how scientists found this place in Mexico, and what it means
to the people who live there. Atlas Obscura is the definitive guide to the
world’s hidden wonders, and this definitely qualifies. And if you’re wondering what it was like
to be there, well grab a headset or a Google cardboard or your phone, because we made a
180˚ VR video inside the butterfly forest. So beautiful. You’re gonna love the rest of this story.

100 thoughts on “Unraveling the Monarch Butterfly Migration Mystery

  1. This is a video I've wanted to make for almost 5 years. Visiting the monarch winter forest was a dream come true, and I am so excited to share it with you. And please check out the video we made over on Atlas Obscura to learn more about the history of this place. Finally, we made a VR180 video so you can feel (and hear!) what it was like to be there. Links to all that in the description. Check them all out, you won't be sorry 🤓

  2. The butterflies are so wonderful, but it makes me kind of sad. As a kid there were butterflies everywhere where I live in South Texas, I could find eggs on milkweed ever year and watch them hatch. The last 5-7 years even though we have milkweed still and I see the occasional single monarch I've yet to find eggs. It feels like there are fewer every year 🙁

  3. Butterflies carry memories from their caterpillar weeks. The migration is tied to a dreaded parasite “Oe” that will otherwise cripple them.

  4. When I was a young boy in 1973, the monarchs changed their usual migratory course and flew through Salt Lake City, Utah. It was a spectacular sight, especially for a boy who was at the right age to be fascinated with all things bugs. The adults all talked about how it had never happened before. It has certainly not happened since. Yet I keep hoping that it might. If you could answer the question of why it happened then, I would be grateful.

  5. Hey there, this kinda relates to something I was thinking of today. I was playing badminton and realize that we have this innate skill of calculating how and when the ball is going to fall and at the same time calculating how we should hit it without even realizing that we are thinking about it. It must be something that has been passed down through genetics right. Like even as a species, we have this weird skill that we use for sports. Can you maybe explain that?

  6. #Life not Lawns let pollinators and the creatures live rather than the toxic, desolate green wastelands we call lawns! If more people d this more pollinators will be able to survive and it only requires we stop wasting so much water and pouring toxic chemicals to grow unproductive nutrient poor unnaturally green grass native to nowhere.

  7. What people of today need to understand is that it is not about the "brain". We "think" it is……but it's not. After Studying Mary Neal and Eben Alexander and all the rest…. we learn there is another life form involved WITH ALL LIFE FORMS HERE ON EARTH. All life forms on Earth are essential "containers". Our brain is an INTERFACE to an additional life form of energy we do not currently understand. Having a sesame seed size brain is not important. What is important is the interface capability of the life form. The brain is important…… but import as an interface. One learning this new information……many many questions we have had in life become reasonable clearer.

  8. They come through San Antonio in October, I believe and… I didnt see any last year. The only butterflies I saw were the snout nosed butterflies that were here because we had a week where it did nothing but rain and it made the food they eat grow more.

    I'm afraid for them.. and the bees. :c The world.

  9. Oh no you taught us something very interesting, but now I’m somewhat disappointed! I want to know whyyyy aaaahhhhhhhrghhhghaahh

  10. Muchas gracias! Thank you for a great video. Beautiful and so well put together with fascinating science facts! I recently visited that very same reserve. Amazing sight to see and quite surreal. I’d love to see more trees planted on route to the site. Again thanks for your video!

  11. Wow! I had no idea about the generations and super generation! Incredible. Thank you for making this video.

  12. You mention preserving the Monarch's at the end of this vid… You must've squashed untold eggs walking on those milk weeds!. Very interesting vid. ✌

  13. I love this video, although you start talking about protecting them? Protecting them from human destruction I presume you are talking about, how can you save anything when your own kind are the ones doing the destruction, then pray for saving the species in one breath, dog save your soul

  14. This encouraged me to start my online monarch conservation community, if anyone would love to join to learn how to restore their population! https://www.facebook.com/tampabaymonarchproject/

  15. you should visit Mr. Lund on youtube… get together… you guys would be great on making future videos for the monarchs

  16. Am I the only one thinking when the butterflies are on the trees they look like the leaves in Fall

  17. 😇WHO'S JOB IS IT TO COUNT THEM? 🐛
    🙏Wouldn't all animals that migrate to different areas have
    a compass?💖much love😊

  18. My favorite example of natural selection how they reproduce and travel such far distances is truely amazing.

  19. I love monarch butterflies! They're so beautiful. I learned about butterflies. Very interesting.🙂

  20. I live in northern Minnesota and you can move without stepping on a 40” milkweed plant. “Not gonna lie”

  21. Wristwatches! Well I do but many people don't. It blew my mind when I realized that we've gone back to using pocket watches to tell the time, except that our "pocket watches" are actually miniature computers we call 'smartphones'.

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