Mysteries of Migration

A parade of elephants in the Ngorongoro Crater

A parade of elephants in the Ngorongoro Crater. Steve Paulson (TTBOOK)

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Original Air Date: 
July 25, 2020

If you had to travel 500 miles across country, on foot, with no map, no GPS, without talking to anyone — to a destination you've never seen, could you do it? It sounds impossible, but millions of creatures spend their lives on the move, migrating from one part of the Earth to another with navigation skills we can only dream of. How do they do it — and what can we learn from them?

We came over one hill and saw hundreds of zebras.
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Imagine driving over a hill and seeing hundreds of zebras or a thousand wildebeest. Anne and Steve were lucky enough to witness this spectacle in the Serengeti. Their expert guide, Moses Augustino Kumburu, describes the Great Migration.

 A herd of topi.

The fact that so many animals migrate — sometimes thousands of miles — has puzzled people over the ages. Why do they take such risky journeys? Conservation biologist David Wilcove studies migration, and he says the scale of migration is staggering.

Greg Dixon (Photo copyright
Photo Gallery

Thousands of sandhill cranes gather each fall on the banks of the Wisconsin River before they head south for the winter. Anne and Steve visited the Aldo Leopold Foundation in Baraboo, Wisconsin to witness this migration firsthand, along with their guide: wildlife ecologist Stan Temple.

Photos courtesy of the Aldo Leopold Foundation

David Barrie is fascinated by how animals find their way. How do they travel thousands of miles across oceans or continents, to a place they've never been, without any other creature to show them the way?

The Maasai have lived alongside the Serengeti wildlife for generations.

Science journalist Sonia Shah, herself the child of Indian immigrants, has long been fascinated with the way animals, people and even microbes move. She says migration is both a crisis and an opportunity.

Show Details 📻
July 25, 2020
February 20, 2021
October 16, 2021
June 11, 2022
April 15, 2023
February 24, 2024
Conservation biologist
Conservation Biologist
Journalist and Author
Full Transcript 📄

Anne Strainchamps (00:15):

It's To The Best Of Our Knowledge, I'm Anne Strainchamps.

Anne Strainchamps (00:29):

In a normal year, there would be millions of people all over the planet in transit right now, packed into planes and cars, taking trips, commuting to work, going on vacation, a constant hum of human migration. And thanks to the pandemic, a lot of that has come to a halt. But in our stillness, there's an opportunity to notice how other migration is still going on, has always been going, on all around us. Billions of animals, birds, reptiles, fish, and insects travel vast distances every year. Moving with the seasons guided by the stars, the geographic cycle of life. Maybe it's time we paid more attention.

Moses Augustino Kumburu (01:25):


Anne Strainchamps (01:25):


Moses Augustino Kumburu (01:26):

Can we move on?

Steve Paulson (01:26):


Anne Strainchamps (01:26):


Anne Strainchamps (01:32):

Last year, when we could still travel, Steve and I went on a short safari in the Serengeti wilderness.

Moses Augustino Kumburu (01:39):

You know Safari's a Swahili word for journey. We wish good journey, [Swahili 00:01:45].

Anne Strainchamps (01:47):

Our guide is naturalist Moses Augustino Kumburu. He's the founder of Moak Safaris in Tanzania. And he knows the Serengeti the way we know our backyard. Even in the rain.

Anne Strainchamps (02:00):

Had cause to comment on your superior driving skills.

Steve Paulson (02:02):

Yeah. I would be so nervous driving here.

Moses Augustino Kumburu (02:06):

It's slippery.

Anne Strainchamps (02:06):

The road is totally mud.

Moses Augustino Kumburu (02:09):

Yeah. And this kind of soil, the black cotton soil, is very slippery when it gets wet like now.

Steve Paulson (02:15):

What happens if you get stuck?

Anne Strainchamps (02:17):

You push.

Moses Augustino Kumburu (02:20):

Push, push, push, push.

Steve Paulson (02:22):


Steve Paulson (02:22):

Oh, are you okay, Anne?

Anne Strainchamps (02:28):

Yeah, I'm fine.

Moses Augustino Kumburu (02:32):

[inaudible 00:02:32].

Anne Strainchamps (02:32):

That's fine.

Steve Paulson (02:35):

That was traumatic.

Anne Strainchamps (02:37):

The Serengeti is the home of the largest animal migration in the world, two to three million wildebeest, zebras and gazelles travel every year between here and the Maasai Mara in Kenya. And on the way, they pass through the Ngorongoro Crater, which is this enormous grassland inside the caldera of an extinct volcano.

Moses Augustino Kumburu (03:10):

So now we are on the floor of the crater which is 19 kilometers wide. So this is like the story in the Bible, the Noah's Ark. So this is really like the Noah's Ark because all kind of animals are here. It's really, really amazing to see.

Anne Strainchamps (03:27):

It is un-utterly beautiful.

Moses Augustino Kumburu (03:29):


Anne Strainchamps (03:31):

The sun is just rising.

Moses Augustino Kumburu (03:33):


Anne Strainchamps (03:34):

The grasses are all still covered with dew as far as you can see, they're just dotted with animals.

Moses Augustino Kumburu (03:41):

Yeah, you'll see here the Thomson's Gazelles. See the wildebeests, the Grant gazelles, I see the jackals over there. Thousands of animals here in the crater. This is a magical place.

Anne Strainchamps (03:55):

It's like seeing the dawn of creation.

Moses Augustino Kumburu (03:57):

Exactly. But you never know, in the grasses here, there are a lot of danger and stuff here like lions, leopards, we just don't see them but for sure they see us. So that's why it's not advisable to just to wander in Serengeti, walking in the tall bushes, you know?

Anne Strainchamps (04:15):

I know. I keep asking if we can stop and walk and you keep saying know.

Moses Augustino Kumburu (04:19):

I know. Yeah, you never know.

Moses Augustino Kumburu (04:27):

So the name of these ones here are called the white beard wildebeests or sometimes the other the name of these, they're called Gnu because of their sound. Gnu, gnu. That's why they're also called Gnu.

Anne Strainchamps (04:42):

This is part of the great migration.

Moses Augustino Kumburu (04:43):

Yeah, this is part of the great migration so now they're heading the east side of the Serengeti to join the bigger herd there. That is where they give birth. Once they start, they'll all drop the babies like crazy.

Anne Strainchamps (05:01):

Why do they migrate?

Moses Augustino Kumburu (05:03):

Because the ground in that area, it has a lot of calcium. Calcium is very good for the animals, it strengthen the bones.

Anne Strainchamps (05:11):

Yeah, calcium and it must be good for the mothers who are then going to nurse the baby.

Moses Augustino Kumburu (05:16):

Exactly, so the milk will be very nutritious for the babies. And also in that area where they're heading, it's short grass so it's very safe for the babies because they can see any predator coming.

Steve Paulson (05:26):

If you look way in the distance there, another huge long line.

Anne Strainchamps (05:33):

Wow. How do they know? From generation to generation, how do they know which route to follow?

Moses Augustino Kumburu (05:42):

Yeah, it instinctive, instinct.

Anne Strainchamps (05:47):

Are they always in some part of the migration?

Moses Augustino Kumburu (05:51):

Yeah, they're always in the move. Almost 2.5 million animals moving according to the time of the year.

Anne Strainchamps (06:01):

It's just incredible to see them just walking. They're and not going fast, they're not going slow, it's just, they're just pacing steadily mile after mile.

Moses Augustino Kumburu (06:11):

It's really one of wonders of nature.

Moses Augustino Kumburu (06:21):

They say they see a leopard in the grass here.

Anne Strainchamps (06:24):

A leopard?

Steve Paulson (06:25):

A leopard?

Anne Strainchamps (06:25):

Moving on. No leopard.

Moses Augustino Kumburu (06:25):

Very elusive.

Anne Strainchamps (06:25):


Steve Paulson (06:28):

Zebras are over there. Zebras.

Anne Strainchamps (06:33):

Oh yeah.

Anne Strainchamps (06:40):

There's a bigger question to ask here. Why do animals migrate? Serengeti's great migration is just one of many. Conservation biologist David Wilcove says the scale is staggering. But climate change is putting some of these journeys at risk.

David Wilcove (07:11):

The mind boggling thing about migration is that it happens everywhere on the planet there are animals, it involves all types of animals from bumblebees to elephants, and it's a critically important phenomenon, both for the environment, and also I think for human welfare and human enjoyment of the world.

Steve Paulson (07:37):

And it's worth pointing out that, as you say, all these different kinds of animal species do this. Some do it over land, some do it, birds and bumble bees, monarch butterflies fly many miles through the air, whales and sea turtles do it through the ocean, salmon swim up rivers, it's kind of extraordinary just how it cuts across the animal world.

David Wilcove (07:57):

Very much so. It's hard to think of any major group of animals where there aren't migratory species. The migrations themselves may differ dramatically, it may be a relatively short migration of moving down a mountain for the winter or it may be a migration that crosses continents.

Steve Paulson (08:17):

So why? Because there are obvious risks involved. I mean physically, it's taxing to travel all this distance, there are a lot of dangers. What are the benefits?

David Wilcove (08:26):

They're definitely risks, and if the benefits didn't exceed the risks, then migration wouldn't persist as a phenomenon. My belief is that most animal migrations are really an example of opportunism, it's taking advantage of a food resource that's available for a part of the year that then disappears later on in the year. So the classic example is the North Woods, they are filled with insects during the spring and summer. If you're insect eating birds it's a great place to raise a family, but you've got to be out of there by the time the cold weather comes in.

Steve Paulson (09:08):

So basically, in most cases, it's chasing after the food, where the food's available. So if there is a Hall of Fame of migratory species, certain extraordinary animals, what would be a few of those animals that you would point to?

David Wilcove (09:24):

Well the oft cited champion for long distance migration is the Arctic Tern, which literally travels from the Arctic Circle, down to the Antarctic and back up again. So it spends most of its life traveling, it's a remarkable journey. There's another tern, the Sooty Tern, where the young hatch and then they go to sea for about four or five years perhaps before they return as breeding birds. And you never see Sooty Terns perched on driftwood or other debris in the ocean, and scientists think they may actually stay on the wing continuously for several years before they come back to breed.

Steve Paulson (10:21):

I'm just trying to imagine how do they get the energy to do that? Obviously they're sleeping as they fly.

David Wilcove (10:27):

That's a great question. Now one of the things we have learned about bird migration is that the energetics of it are complicated, but perhaps it's not as costly an activity as we might have thought. There's a German scientist, Martin Wikelski, who studied migrating thrushes in the Midwestern United States and he found that they actually expend about the same amount of energy migrating in a given night as they would expand if they were just huddled down in the woodlot for the evening and not migrating, because it was getting cold and it was taking a fair amount of energy to stay warm. And we do know that birds will take advantage of thermals and other things to sort of make the journey a little bit easier.

Steve Paulson (11:18):

Yeah. We've been talking about the glory of animal migrations, truly one of the great spectacles in the world. You have also written at that a number of these migrations are in decline, especially some of the mass migrations and some of the habitats are disappearing. How serious a problem is this?

David Wilcove (11:35):

Well, I think almost all the great animal migrations are in trouble and a lot of the great ones have disappeared completely. We don't have the great herds of bison that we had 200 years ago, the flocks of passenger pigeons that darkened the skies in the colonial era. gone completely.

Steve Paulson (11:57):

And we should put this in perspective. So everyone has heard that the passenger pigeon has gone extinct. What we may not realize is how common these birds once were.

David Wilcove (12:06):

They were so common that their migrations lasted over a period of several days, and put the land over which they were migrating in this sort of eerie unnatural Twilight because they were so common that they darken the skies and somewhat obscured the sun. That's how abundant they were.

Steve Paulson (12:28):

You're talking about hundreds of thousands, maybe millions of birds.

David Wilcove (12:32):

Hundreds of millions.

Steve Paulson (12:33):

Hundreds of millions at one time?

David Wilcove (12:34):

Yes. It was at one time probably the most abundant bird in the world.

Steve Paulson (12:38):

It's astonishing to think that that bird could then disappear, could go extinct.

David Wilcove (12:42):

September 1, 1914, the very last one died in captivity.

Steve Paulson (12:47):

Just because people shot them?

David Wilcove (12:49):

Largely due to that. It was a combination of this sort of ruthless over exploitation for the market, combined with the wholesale clearing of forests, compounded by the fact that even though this was an incredibly abundant bird, this huge population only nested in a few places, these were enormous nesting colonies. But they were discreet, and so the hunters could disrupt each and every one of them and that's more or less what happened. And in a surprisingly short period of time, the birds were snuffed out.

Steve Paulson (13:26):

And that's, I suppose, the species that are especially at risk, the migratory species are those that go to a particular place. The Monarch Butterflies who are flying down from North America in the winter and go to this one part of Central Mexico this mountainous forest.

David Wilcove (13:43):

That's right. When the species aggregates in a few discreet spots, it's frighteningly easy to destroy the populations by destroying those spots. Of course the paradox is it's also relatively straightforward to conserve them because you know precisely the places to protect them. But the unfortunate thing is, around the world, the great animal migrations are disappearing, the populations of songbirds in Eastern North America are down anywhere from 50 to 75% over the past half century.

Steve Paulson (14:23):

Why's that?

David Wilcove (14:24):

Largely due to a combination of habitat loss in North America, as well as in the Caribbean and Central America where many of the spirits winter. We've seen salmon runs decline in the Pacific Northwest over the past century largely due to the great dam projects which certainly brought huge benefits to people in the Pacific Northwest, there's no doubt about it, but it also snuffed out these extraordinary salmon run.

Steve Paulson (14:56):

So you can understand that as human development just keeps increasing around the world, there are fewer wild places, certain habitats are destroyed, forests are cleared. It sounds kind of just like this unrelenting horror story but isn't quite that bad?

David Wilcove (15:13):

It's a bad situation but it's by no means a hopeless situation, and you do see increasing efforts to protect some of the great animal migration. So just within the United States for example, the discovery of some long distance pronghorn antelope migrations within the past 10, 15 years, prompted state officials to work together to protect the migratory routes.

Steve Paulson (15:41):

How do you do that?

David Wilcove (15:42):

You ensure that people don't block the key pinch points of migration with fences or with development that would be hostile to the animals moving across, you basically give them a safe passage way. That's the real challenge is that migratory animals pay no attention to the sorts of administrative boundaries that are so important to us.

Stan Temple (16:09):

Right, we might be obsessed with borders, trying to keep certain people out of another country, but that doesn't work in the animal world.

David Wilcove (16:17):

Exactly. And so it requires a level of coordination across boundaries, whether it's one state working with another state or one country working with another country, and we're slowly learning how to do that. So we can and we do take actions to protect these species. My argument would be that we have to do more.

Anne Strainchamps (16:48):

That's David Wilcove, a conservation biologist at Princeton University, talking with Steve Paulson.

Anne Strainchamps (17:03):

I said earlier that we're looking for lessons from super navigators today. One is that life on the move is a lot more common than we tend to think, and another is that migration is a collective experience. In the Serengeti, the wildebeest lead the great migration but they have fellow travelers, including Steve's favorite, Zebras.

Steve Paulson (17:25):

Look, the zebra, look you just can't, look down there. My God, they just keep going. They're hundreds long.

Anne Strainchamps (17:38):

It's like the great gathering of the clan. It's as far as the eye can see.

Steve Paulson (17:43):

How [inaudible 00:17:44].

Anne Strainchamps (17:52):

The white and black against the bright green grass. Oh God, they're gorgeous.

Moses Augustino Kumburu (17:59):

Yeah, this is part two of the migration. You remember saw those...

Anne Strainchamps (18:02):


Moses Augustino Kumburu (18:04):

... Wildebeest marching here? So they are all coming to join these [inaudible 00:18:07] here.

Anne Strainchamps (18:08):

This is hundreds and hundreds of zebras.

Moses Augustino Kumburu (18:11):

Hundreds and hundreds, yeah, endless, you can see everywhere, the stripes everywhere, black and white. If you compare one to another on this patterns you can see the differences, they're all different like a fingerprint.

Anne Strainchamps (18:21):

And why do the zebras migrate with the wildebeests?

Moses Augustino Kumburu (18:25):

They defend each other because zebras have a very good eyesight and these wildebeests, they have a very, very good sense of smell. So together they can be safe.

Anne Strainchamps (18:34):

So the zebra might see a predator and the wildebeest might smell...

Moses Augustino Kumburu (18:37):

Might smell.

Anne Strainchamps (18:39):

.. the predator so together that keeps them safe.

Moses Augustino Kumburu (18:41):


Anne Strainchamps (18:42):

Do they eat the same food?

Moses Augustino Kumburu (18:44):

Zebras prefer tall grass, and the wildebeest short grass.

Anne Strainchamps (18:48):

Oh, so even there, they're not competing exactly for food.

Moses Augustino Kumburu (18:51):

Exactly. Even there there's no competition of food, that's why they are kind of no problem for them moving together.

Anne Strainchamps (18:57):

That's lovely, kind of this ancient kinship.

Moses Augustino Kumburu (19:01):

Oh yeah, that's true.

Steve Paulson (19:05):

Oh look, they're starting to cross the river.

Anne Strainchamps (19:09):

What is that?

Moses Augustino Kumburu (19:10):

The sound of zebra. The vultures there.

Anne Strainchamps (19:19):

Oh my gosh yes. What are they...

Moses Augustino Kumburu (19:20):

The vultures, they're also migrating with the herds.

Anne Strainchamps (19:25):

Why? Are hey waiting for somebody to drop dead?

Moses Augustino Kumburu (19:27):

Oh yeah, they're waiting for somebody to die or to be eaten so they can finish everything. They are like housekeepers because they're cleaning everything. After the lion or leopard or cheetah eating something then they come and finish everything so that's why you don't see any dead animal. So they help to stop disease outbreak. That's why I call them housekeepers.

Anne Strainchamps (19:54):

Because most people just scorn them.

Moses Augustino Kumburu (19:57):

Oh yeah, exactly. They're playing a very, very important role here in the ecosystem. They're very, very important.

Anne Strainchamps (20:06):

Zebra crossing.

Moses Augustino Kumburu (20:07):


Anne Strainchamps (20:09):

He's trying to decide. Can I cross?

Steve Paulson (20:11):

Can I get across?

Moses Augustino Kumburu (20:11):

Okay, [inaudible 00:20:11].

Steve Paulson (20:11):

Yeah, okay. [inaudible 00:20:18].

Anne Strainchamps (20:25):

Coming up, you don't have to go to Africa to witness a great migration, just look around. I'm Anne Strainchamps, it's To The Best Of Our Knowledge from Wisconsin Public Radio and PRX.

Anne Strainchamps (20:51):

If you live in the Upper Midwest, you know that winter's on the way when you hear Sandhill Cranes flying overhead. If you've ever seen one, a Sandhill Crane is a tall bird with a scary sharp beak and bright red top knot, and they're one of the great conservation success stories. They were one so endangered, the population was nearly wiped out. Wildlife ecologist Stan Temple is one of the people who helped bring them back by figuring out their migration pattern. So on a cold day last fall, we went with him to watch the cranes gather on a small island in the Wisconsin River before they headed south. As always with cranes, you hear them way before you see them.

Stan Temple (21:35):

The maximum number that we've had has been 14,000 and we normally have 10,000 to 12,000 birds in here by this time of year. And on this particular island in front of us, we've had 6,000 or 7000 birds. It's pretty packed out there, the late arriving birds actually kind of like a plane having to go around on a runway they have to circle a couple of times to find a bare piece of ground to land on.

Anne Strainchamps (22:15):

Sound is amazing. Do they have different calls that they make?

Stan Temple (22:19):

This time of year, it's just like people in a large crowd, there's a den of chatter among them. Cranes produce a very loud sound. They have a very long, convoluted trachea, kind of the same effect that you have with a French horn or something with a long passageway for the sound that it kind of amplifies it and it comes out very loud. I've always loved the Aldo Leopold's description is the trumpet in the orchestra of evolution, just perfect.

Stan Temple (23:00):

We really knew virtually nothing about Sandhill Crane migration prior to our work. And it's true of most bird migrations, okay, they're here today, gone tomorrow, but you don't know where they came from, you don't know where they're going, unless you can follow them, which is what my students and I did, it's how we sort of wrote the book on Sandhill Crane migration is because we have radio birds that we were able to follow and know all of the little tricks of Sandhill Crane migration, when they stopped, where they stopped, why they stopped there.

Anne Strainchamps (23:33):

Were you following them in a plane?

Stan Temple (23:35):

We had both a plane, and people on the ground and vehicles tracking them. It's not easy because the cranes are moving pretty fast. You'd get lost on the ground, the road system just didn't go in the direction the cranes were going and you had to make some wide detours. But the plane often bailed us out.

Speaker 7 (23:55):

I think maybe what we're gonna do we're gonna keep the windows closed until some birds hopefully start to come into our hideout here, otherwise it's gonna get pretty breezy and wet in here. We'll open it up when we think we've got something really to look at. I'm just afraid that this brisk wind is going to discourage the birds landing where they normally land on this island.

David Berry (24:23):

They know where to go.

Stan Temple (24:25):

It's pretty easy for animals to do direction, to know north from south and all. I mean, we can do that, we're not very sophisticated in migration by looking at the sun and the stars we can figure out where north is. But if I give you a compass, essentially something that will tell you direction and I asked you to find your way to Florida, you can't do it, just knowing the direction isn't good enough you have to have a map. And that is something that they either have inherited genetically in the case of birds, for example, they don't migrate with their parents, they make that first migration all by themselves, may have inherited a genetic map. Birds like Sandhill cranes and waterfowl they migrate, on that first migration with their parents have basically been taught.

Anne Strainchamps (25:18):

What are they even noticing? What are they picking up that [inaudible 00:25:23]?

Stan Temple (25:23):

Well, it's really important. This is a life or death matter. So for birds that migrate at night, which is most of our small songbirds, they're navigating using the stars. But what happens when they migrate under a cloudy night? They can't see the stars. It's kind of like an airplane or NASA sending up the spacecraft, you have to have some kind of backup navigation system. And for birds, if their best, most accurate navigation system is unavailable, they will shift to the next best of their redundant systems, and the next best for some birds might be geomagnetism. They can detect it, it's not as accurate as having the stars or the sun, but you can detect it and they can at least keep you roughly on course. Others use prevailing winds and if they're migrating along the coast, they can hear the waves crashing on the shore and know that I've got to always keep that sound to my left, and it means I'll be going in the right direction.

Speaker 7 (26:30):

[inaudible 00:26:30] from about that tree you can see out this window to hear...

Stan Temple (26:34):

A good amount have already landed.

Anne Strainchamps (26:38):

Oh where?

Stan Temple (26:38):

On this left side, on the far side of the island. I'm guessing we're going to get some nice flybys.

Anne Strainchamps (26:51):

I know you're a scientist but is there something you find beautiful about migrations.

Stan Temple (26:56):

Oh, it's fascinating, of course, it's beautiful to watch the birds doing it. Seeing them rising up in the air, hundreds or thousands of cranes circling and a thermal is quite an impressive visual sight. And of course, as usual, they're noisy. So for most people, they know they're around because they hear the noise and the look up and hear these little tiny specks thousands of feet in the air.

Anne Strainchamps (27:31):

Stan Temple is a Wildlife Ecologist at the University of Wisconsin, and a senior fellow at the Aldo Leopold Foundation.

Anne Strainchamps (27:45):

We're in a golden age of animal tracking, but somehow, the more we discover, the more mysterious animal migration seems. David Berry has traveled around the world, from the Australian desert to the South African bush, studying the superstars of animal migration. A species he calls super navigators. You'd be surprised how many tiny creatures have navigational skills we can only dream up.

David Berry (28:15):

The monarch butterfly, like a lot of other insects, and indeed other animals besides insects has what's called a time compensated sun compass, which sounds complicated but it's quite simple. The insect can detect the position of the sun in the sky and can use that to maintain a steady course. Now, because the sun is constantly moving across the sky, it needs to compensate for that movement. So it actually also has an internal clock that enables it to make an allowance to compensate for the changing azimuth of sun and keep flying straight in a broadly southwesterly direction.

Anne Strainchamps (29:00):

So it's really got a tool almost, a tool inside its brain that we don't have which computes both time and light.

David Berry (29:09):

And angle.

Anne Strainchamps (29:11):


David Berry (29:12):

A remarkable thing for a creature so small with a brain the size of, well, not even a grain of rice. It's a tiny, tiny brain with only a few hundred thousand neurons in it.

Anne Strainchamps (29:26):

But reading your book, that's what comes up over and over again, some of the tiniest creatures on the planet have some of the most remarkable navigational abilities. The dung beetle was discovered fairly recently, they navigate by the light of the Milky Way?

David Berry (29:42):

That's right and they're not the only ones. The nocturnal dung beetle is a truly fascinating insect and, well I should explain that what dung beetles do is they find a pile of dung and they go to the dung and they collect a piece of it and they turn it into a beautiful little sphere, and then using their real legs, they roll this sphere, away from the pile of dung to their nest where they can feed on it and lay eggs in it and what have you. And it's very important that they get away from the pile of dung as quickly as possible because other dung beetles otherwise will mug them and take the ball of dung off them. And to go as quickly as possible, you need to go in a straight line, you don't wanna go curving around and coming back to where you started. So they have to go straight, and the way they do that is they tend to use the light of the moon.

Anne Strainchamps (30:36):

What if there's no moon?

David Berry (30:39):

Ah well, exactly. There's Eric Warrant, whom I interviewed for the book, told me a funny story. He said that they published the results about polarized moonlight navigation, and then a while later, they were out in the desert in South Africa doing some more research and they were sitting around their kind of campfire having a beer, and the moon hadn't yet risen. So they thought they couldn't really do anything and they'd laid out some dung. And then they noticed that the dung beetles were beginning to fly in, they were drawn by the smell of the dung and they were landing. And the moon hadn't risen, but they were rolling balls of dung away. And Eric and his colleague Marie were really quite alarmed because they suddenly thought, "Maybe we got it all wrong."

Anne Strainchamps (31:29):

Oh my God, we got it wrong.

David Berry (31:29):

Maybe we don't need the moon. So then they basically looked up at the brilliantly dark night sky out on the edge of the Kalahari Desert, no light pollution, just this amazing brilliant starlit sky and they noticed, of course, the band of the Milky Way, hidden from most of our city dwellers of course. They looked at each other, they said, "God, maybe, is it possible? Could they maybe actually be using the Milky Way." And they then proceeded to perform some absolutely delightful experiments. First of all, they put some little cardboard hats on the beetles which prevented the Beatles actually seeing the night sky. And sure enough, they couldn't steer straight. And then they thought, "Well, we better make another experiment to see whether it's just having a hat on that upsets them." So they made transparent hats. And when the hats were transparent they could navigate again.

Anne Strainchamps (32:30):

There were things I didn't understand. One of the things that always seems most mysterious to me is how many animals migrate with incredible precision to a very particular destination without ever having been there or been shown where or how to go. Like sea turtles. They'll hatch from eggs, they're no parents anywhere around, nobody is going to lead them and they swim off to the exact right island.

David Berry (32:58):

Yes, it is absolutely astonishing. And what we do know is that loggerhead turtles that hatch on the coast of Florida, they are definitely the most impressive magnetic navigators because the tiny little hatchlings, they perform an extraordinary journey, they get caught up in the north flowing Gulf Stream and then they're taken right the way around the entire North Atlantic Ocean using ocean currents. But in order to do that, they need to know which way they're facing. And Ken Lohmann, at the University of North Carolina in Chapel Hill, has done wonderful experiments which are now really part of the bedrock of animal navigation science in which he took little hatchling turtles and altered the magnetic field around them and he could make these little hatchlings head in different directions. And the directions in which they head seem to be, as it were designed to enable the hatchlings to stay safely inside the current which will bring them back to their home beaches.

Anne Strainchamps (34:06):

It strikes me that there are a couple of reactions. I have one is to marvel at humans ability to figure all of this out, that's extraordinary science. But the other is to really see all of this as a story about perhaps the beginning of the decline of the myth of human exceptionalism. It seems like the story that's emerging is that paradigm of animals as being not only not inferior to us but in some ways superior.

David Berry (34:42):

Yeah, I totally agree. I think it's a really important lesson that one can learn. And animal navigation studies are certainly a wonderful window onto the amazing abilities of other species. Because to be honest, although human beings are obviously brilliant in some ways that we've developed tools that enable us to navigate with amazing precision, notably of course GPS, our natural navigational abilities, unless specially cultivated, are really nothing compared to the sorts of things that we've been discussing. Indigenous peoples, however, are capable of some truly astonishing feats. So if you look at the Inuit hunters of Northern Canada or the aboriginal tribes people of the desert regions of Australia, or of course Polynesian Islanders, all of these indigenous peoples have truly astonishing navigational abilities and they don't make use of maps, compasses or any tools of any kind, it's all based on their senses and their natural wits.

Anne Strainchamps (35:55):

What's an example of the way the Inuits or Pacific Islanders, what can they do that we GPS addled brains can't?

David Berry (36:04):

Well, let me talk a little bit about the Pacific Islanders, the navigational specialists, because they're specially trained and selected. Start at a very early age and they are taught the precise positions on the horizon at which 32 named stars rise and set every night. And they can use those stars to maintain a steady course in any direction they choose. So that's the star compass.

David Berry (36:35):

On top of that, however, out on the open ocean, they can also use patterns of swell. So swell is a waveform that is not produced by local winds but it's generated by storms, often hundreds or thousands of miles away. These swells follow very, very regular courses across the ocean. So these navigators use the patterns of swell also as a kind of compass. They can detect the swells, and they can steer by them. More remarkable though, still, when they get close to an island target, which may be completely invisible because it's low lying, they can also pick up the reflections of the waves from that island and they can work out from those the direction in which to sail to get to the island.

Anne Strainchamps (37:31):

Wow. So to make clear this is imagine if they would be standing on the beach of one particular island just looking out at what to us would be just an empty flat horizon of ocean, but that's not what they see.

David Berry (37:49):

No. And indeed they see the ocean as being their home. But let me give this a bit of context because I'm not talking about little journeys of 10,20 or even 100 miles, I'm talking about journeys of, in some cases, thousands of miles.

Anne Strainchamps (38:03):


David Berry (38:03):

And indeed the Polynesian Voyaging Society which was set up in the 1970s to develop these skills and sustain them, has conducted some extraordinary voyages using these traditional techniques, not just around the Pacific, but around the world. So it's a happy thing that in Polynesia at least, these traditional indigenous skills, truly remarkable cultural artifacts that date back for thousands of years have been not only recovered but preserved. I'm afraid though that the same is not necessarily true elsewhere and I think there are real concerns about what will happen to the equally impressive expertise of the Inuit that I mentioned and indeed Australian aboriginal tribes too and many others. These are precious heirlooms of our human ancestry and for them to be lost, just because it's more convenient to press a button on a gadget, would be tragic.

Anne Strainchamps (39:13):

That's David Berry. His book is called Super Navigators: Exploring the Wonders of How Animals Find Their Way. We've been talking about animal migration as this amazing natural phenomenon. But have you ever noticed that when it comes to humans, we almost always frame migration as unnatural. Journalist Sonia Shah has been wondering about that for a very long time.

Sonia Shah (39:42):

I think I've always been interested in inequality.

Sonia Shah (40:08):

My parents used to take me to India, which is where they had grown up. I used to spend my summers at my grandmother's tenement building in Mumbai, watching over the banisters at the alley below where there were people who lived on the street down there.

Sonia Shah (40:27):

And I would watch the little kids, who look just like me, they'd be having their bath on the street, where everyone could see them next to the cows and the people walking around in the buses and the taxis, and then I would have my bath and like a nice child bathroom with running water.

Sonia Shah (41:00):

This difference always really struck me. Why do they have to live like that and why do I live the way I do? Growing up, I never really got a good answer to that question. My parents would say, "Well, it's because they don't have good jobs." And then I'd say, "Well, why don't they have good jobs?" And they said, "Well, because they don't have good education." And I'd say, "Well, why don't they have good education?" And they would say, "Well, because they're poor."

Anne Strainchamps (41:31):

We'll hear more from Sonia Shah next. I'm Anne Strainchamps. It's To The Best of Our Knowledge from Wisconsin Public Radio, and PRX. Science journalist Sonia Shah has a knack for uncovering trends before they become headlines. A few years ago, she wrote a book called Pandemic, and today, we're living in one. She has a new book out called The Next Great Migration, in which she makes the case that we humans are like many animals, a migratory species, and that challenges some of our deepest beliefs about what it means to call a place home.

Shannon Henry Kleiber (42:10):

Migration is inherently dangerous and difficult. So why do we do it if we aren't forced to do it? Or does it take being forced to do it to happen?

Sonia Shah (42:20):

I don't think we know the answers to that question but what I tried to expose in the book is that there must be huge benefits because we know the costs, as you mentioned, are huge. I mean we're living through some of the costs of movement right now with this pandemic. And yet, what we're discovering is that there's so much movement going on right now in the present among wild species and humans, but also in the past. If you look at specific migrations, this idea that it's only propelled by a catastrophe doesn't really hold up. People moved, migrated into the remote islands of the Pacific in prehistoric times, just set off from Asia in canoes not knowing where those specks of land might be that they would land on.

Sonia Shah (43:09):

For a long time there was this idea that, oh, that must have happened by mistake because surely no one would purposely do that. But it turns out that, yes, we did it purposely we didn't do it purposely just once, we did it multiple times over and over and over again. People migrated into the Tibetan plateau in the highest reaches of the Himalayan Mountains where there's not even enough oxygen to breathe. So these are all clues I think that point is towards the answer to the question you're asking.

Shannon Henry Kleiber (43:38):

Your last book was called pandemic and I wanted to talk about that for a little bit. How are pandemics and migration related?

Sonia Shah (43:47):

Well, roughly speaking, contagions generally are a function of animals, peoples and microbes moving around in different ways and colliding in different ways. If you look at Ebola, for example, as a virus of bats, it spills over into humans, that happens in some forest area in West Africa and then people carry that into cities and so we have the movement of the bats relating to the movement of the microbes and then the people moving around and contagion is one of the effects of our mobile health planet.

Shannon Henry Kleiber (44:25):

What about the idea that we belong in a place? A place is our home. Is that concept changing or is it changed forever?

Sonia Shah (44:34):

I think there's a tension there because I think we want to belong to certain places, but at the same time, we also need to reckon with the fact that we are very mobile and we've moved a lot over the course of our history. What we now know is that people moved out of Africa, of course, but then didn't stay put once they got to certain places, so there's this idea of dispersal out of Africa into an uninhabited planet and then people got to Europe and the Americas and Asia and then they just kind of stay there for a millennia until the modern moment of migration through fast ships and planes and all that.

Sonia Shah (45:14):

But what scientists are piecing together from genetics of ancient DNA is that people moved into the Americas and then moved back into Europe and back to Africa. People went into Asia and then went to Europe and then back to Asia and then back to Africa and it was this complicated movements were happening, just like they are today, but they were happening in the deep past. And so this idea of "where do you belong?" is really kind of a, it's an artifact of a time when we didn't think of ourselves, we didn't understand ourselves as a migratory species, a species that moves a lot.

Shannon Henry Kleiber (45:56):

And some of that too strikes me as the can be racist and xenophobic the idea of we belong to one place, you don't belong to that place to us and then?

Sonia Shah (46:07):

I trace it back to Carl Linnaeus, who was sort of the father of modern taxonomy, and he decided where everything belonged, he named the living world and thousands and thousands of species, he came up with a system for naming them, and he decided that, okay, people in Africa belong in Africa, people in Europe belong in Europe, people in Asia and in Asia, and people in the Americas belonging in Americas to such an extent that he said they were biologically isolated from each other and biologically alien to each other. T

Sonia Shah (46:41):

That people who live in different continents were different subspecies of humans and in fact, people from Africa, he said, were almost subhuman, that they were not fully homosapiens, but the hybrid product of homosapiens and this other species of humanoids called troglodytes, and we see that idea of people of African descent as subhuman to this day with the killing of George Floyd, I mean that was the first thing I thought of you look at the man's face as he has his knee on this, this other person's neck, and he has this nonchalant expression and his hands are in his pockets and it's very much like he doesn't think that person under his knee is fully human. And that is a very old idea and we see it, it's still so alive in our politics to this day.

Shannon Henry Kleiber (47:40):

How can we move on from that, what can we do?

Sonia Shah (47:45):

I think part of the understanding of ourselves as having a shared humanity, means that we're going to have to recover our lost history of migration and the ways we are all connected. So the white nationalists, for example, they have this thing where they chug milk. That's like a big sort of white supremacy thing and they get together and they chug milk and it's supposed to indicate that they're Europeans and only Europeans are able to digest milk because they have a special gene that allows them to do that. But what they forget is that same gene exists in nomadic people from parts of Africa, from parts of Middle East, to camel herders, there's a number of different peoples who also have that gene.

Sonia Shah (48:32):

The fact is, those differences are fuzzy, they're nebulous. We do all have this shared ancestry because we have moved around. So those connections that migrants create, I think that's what we need to recover, it's part of overcoming this old idea that we are naturally split into continental races that are color coded by each continent, the black people in Africa, the white people in Europe, the yellow people in Asia, the red people in the Americas. This is what Linnaeus said, and it still is so deeply ingrained in how we think today. But science has moved on since Linnaeus, and we know that we have more in common across those boundaries of race than within them, because we've all moved around so much. Whenever people move into a new place, they mix with the people who are there. We meld very easily so the genes in migrants bodies spread into the host population so they enter and that's a process that works and that is ubiquitous.

Anne Strainchamps (49:42):

Sonia Shah is a science journalist and author of The Next Great Migration: The Beauty and Terror of Life On The Move. She spoke with Shannon Henry Kleiber. We began this hour talking about migration as a natural wonder, something that's going on all the time, right under our noses. And we talked about wayfinding as an ability, a skill that can be learned and passed down from one generation to the next. We're all navigating unfamiliar territory these days, and so we can choose to focus on what's scary or we can try to think of this as what humans and animals have been doing for a very long time, moving, adapting, finding our way.

Anne Strainchamps (50:39):

To The Best Of Our Knowledge is produced in Madison, Wisconsin at Wisconsin Public Radio by Shannon Henry Kleiber, Charles Monroe-Kane, Angelo Bautista and Mark Riechers. Our technical director is Joe Hardtke. Our executive producer Steve Paulson, and I'm Anne Strainchamps. Thanks for joining our journey today.

Speaker 11 (50:58):


Last modified: 
February 23, 2024