Today at Reader's Corner, Scott Weidensaul, author of A World on the Wing, The Global Odyssey of Migratory Birds.I'm Bob Kustra.Welcome to Reader's Corner.
In the past two decades, our understanding of the navigational and physiological feats that enable birds to cross immense oceans, fly above the highest mountains, or remain in unbroken flight for months at a stretch has exploded.
What we've learned of these key migrations, that is, how billions of birds circumnavigate the globe, flying tens of thousands of miles between hemispheres on an annual basis, is nothing short of extraordinary.
In his latest book, A World on the Wing, Scott Widensall unveils the miracle of nature taking place above our heads.He introduces readers to those scientists, researchers, and bird lovers trying to preserve global migratory patterns
in the face of climate change and other environmental challenges.Scott Wiedensahl is a writer and researcher specializing in birds and bird migration.He's the author of nearly 30 books, including the Pulitzer Prize finalist, Living on the Wind.
Scott Wiedensahl, welcome to Reader's Corner.
Well, thank you, Bob.It's a real pleasure to be here.
You know, Scott, people are always asking me, how do you pick your books?Well, I have all kinds of answers for that.Like, you know, I go to bookstores and I look around and I go on to Amazon and I attend a lot of
sessions where authors are speaking and all of that but on this one I'm a longtime bird feeder and bird observer.I can't call myself a bird, a birder who goes out on trips to follow birds but this book just caught my eye.
There's many books like this out there but I really was fascinated by what you were trying to get across in this book, these global migratory patterns and just how astounding they are.
Maybe we could begin, though, with having you tell us, as I said before we went on the air, you've got quite a gig.You travel the world.
That's good and bad, away from family, but nonetheless, it's a great opportunity to see what's going on around the globe.This all started for you, I guess, in Pennsylvania as a kid, is that right?
It did, yeah.I grew up in the mountains of eastern Pennsylvania, and not all that far from a place called Hawk Mountain Sanctuary, which was the world's first sanctuary for birds of prey established back in the 1930s.
And it sits along the Kittatinny Ridge, which is the front range of the Appalachian Ridge and Valley system. And every fall from late August until almost Thanksgiving, about 20,000 migrant hawks, eagles, and falcons come pouring down that ridge.
And I got hooked on, well, basically I got hooked on three of the most important things in my life on the same day in the autumn of my 12th year.
My first trip to Hawk Mountain, where just by dumb luck, we arrived on one of the best migration days of the fall.It had been a cold front the night before.
The wind was blowing out of the northwest, which is the conditions you need for a good Hawk flight in the east.I'm a little kid sitting on a rock with a pair of cheap binoculars.
golden field guide to the birds that i have been studying you know you know intensely nothing in the sky look like anything in the book twelve twelve it doesn't stop you just yelling out you know bad identifications as these birds are going by i was just on fire and then there was a there was a an older woman sitting on the rocks in front of us in the
North look out of hawk mountains is big boulder field about a thousand feet above the valley and she kept turning around and kind of glaring at me every time i bellow out some some wrong identification she finally had a side and sit down next to me she said son sit down you don't know what you're talking about and then started to pay to patiently.
teach me hawk identification.Her name was Jean Litzenberger, and she became one of my mentors.But that day, Bob, three things happened to me.
I got hooked on the Appalachian Mountains, along which these birds were flying, and among which I had grown up, without realizing that it was this 2,000-mile mountain range from Newfoundland to Alabama, along which all of these raptors were traveling.
I got hooked on birds of prey that day because, let's face it, birds of prey are cool. But most of all, I got hooked on migration.
The notion that there were birds that had been born in, you know, the Arctic of Greenland on their way to, you know, Southern South America that were flying, like, literally over my house, that just opened up a world of magic for me.
That was 50 years ago last fall, and I haven't lost my passion for any of those three subjects, especially migration, ever since.
Well, it's clear from your book, A World on the Wing, that you haven't lost that passion.It's a great way for people to get introduced to what's going on out there.
In the introduction, I mentioned that the knowledge of bird life has exploded thanks to technology, really.
I wonder if you could share with us the banding of birds, how it was done for years and the newly miniaturized technology that really allows scientists to get so much more information.
Oh, sure.People have been marking birds for, in some cases, hundreds or more than a thousand years.We've got records of falcons, royal falcons that escaped from their owners in Europe in the Middle Ages that were found hundreds of miles
a way that began to tell people that these birds move great distances.
But it's really only been about the last 120 years that scientists have been using sort of a formalized system of putting leg bands with unique serial numbers on the legs of birds, bird banding.
to find out, I mean, almost everything concrete that we know about the lives of wild birds, you know, comes from marking them as individuals.Look, one robin looks the same to us as any other robin.Robins can tell each other apart, but we can't.
But once you put a leg band on that bird or mark it in some way as an individual,
Then you can start to unravel where it goes, how long it lives, whether it comes back to the same place in the summer, whether it goes back to the same place in the winter, whether it has the same mate from year to year or even within the same year.
You can start to tease apart all of these things.I've been banding birds now for more than 40 years.
I got my start helping the research team at Hawk Mountain in the 1980s banding hawks and eagles and falcons and then moved into owls and hummingbirds and songbirds and all sorts of other species.
Banding is still of fundamental importance, but it's really labor-intensive, and you're playing the odds, and the odds are not good.Only a fraction of a percent of all the songbirds that are banded are ever encountered or recovered again.
So it takes a long time to build up the information you need to start to stitch together migration routes and other questions.
You hinted, though, that technology has really opened up a new world here, because with the miniaturization of electronics, and especially the miniaturization of batteries, we've been able to put a variety of tracking devices, not all of them transmitters, some of them are data loggers that just record information.
For example, I've been working for about the last seven or eight years with colleagues at Denali National Park in Alaska, studying the migration of songbirds that breed in the wilderness of central Alaska.
And we've used what are known as light-sensitive geolocators, which are little data loggers that simply record light levels 24 hours a day for about a year or so.And also there's a little clock in there and a microprocessor.
And when the bird comes back again the next year, it comes back to the same breeding ground and you recapture it, if you recapture it.
you can download the data and see roughly where that bird has been for the last year, or what are known as pinpoint GPS tags that communicate periodically with the GPS satellites overhead and store a very precise location at preset intervals, maybe, you know, 50 times over the course of the next year.
You can start to figure out with a remarkable degree of accuracy where these birds have been.And it is,
a very cool experience to recapture a Swainson's thrush that you tagged in the spruce forest of Alaska and watch the data unspool on your computer screen and realize that that bird flew 8,000 miles to the montane forests on the eastern slope of the Andes between Bolivia and Argentina and then came all the way back again.
And you have this thing in your hand that weighs not much more than air. that is making this, you know, incredible transhemispheric journey every year.
And for our listeners who might be thinking, boy, would I like to do that?
The answer is if you live in Idaho, especially Boise, Idaho, you can do it because Boise State University has the Intermountain Bird Observatory and they put up these huge nets and they collect these songbirds and they band them and they send them back in.
And I've participated in it, and I've held these little guys in my hand while they were banded and measured and weighed.And we also capture raptors.That's something to see.I won't go into the details on that one.
But, Scott, it's good to know that we've got something right here in Boise that really helps our readers understand and connect to how this is done.
Well, and you raise a good point, which is that a lot of this work, a lot of this migration research is done by paid professionals.But a lot of it is done by really talented, really dedicated, highly skilled amateurs.
And I don't like using the word amateur because it makes it sound like they don't know what they're doing.Advocational banners make it sound like it's a hobby.
But ornithology is a branch of science that has always been very welcoming of sort of non-academic specialists.I'm a really good example of that. I am a college dropout.
I do not have an academic degree in science, and yet I'm also a fellow of the American Ornithological Society because of the fact that I have been doing this work for 25 years, working with a whole host of colleagues, doing good science.
This is one way that ornithology, I think, differs from a lot of branches of science.
You're listening to Scott Weidensaul.He's the author of A World on the Wing, The Global Odyssey of Migratory Birds.
Well, our listeners should know that if you go to the website of the Intermountain Bird Observatory, you'll see all kinds of opportunities to volunteer.That's exactly what I was when I did these things and I know they're always looking for people.
So let's talk about the migration itself.Why don't you just give us a thought on the longest migratory route? that a bird travels, in your experience, what would that be?
Well, at this point, I think the record holder, and this is always subject to revision because we're constantly learning new things, the new record holder is the old record holder.
Back when I wrote my first book about bird migration, Living on the Wind in the 1990s, we assumed that the longest distance migrant was the Arctic tern because they breed in the highest latitudes in the northern hemisphere, they winter in the southern ocean,
around Antarctica, so we figured 22,000 to 25,000 miles, just drawing some lines on the map.Once we got tracking devices like geolocators small enough to put on Arctic turns, These suckers are going all over the place.
Arctic terns that breed on the coast of Maine, some of them winter in the Indian Ocean.They're traveling up to 61,000 miles a year.This is a bird that's the size of a morning dove, for God's sake.I mean, it just is astonishing.
In terms of the longest nonstop flight by a land bird, I mean, Arctic terns can live for months or years at sea without a problem.But for a bird crossing completely inhospitable habitat,
probably the bar-tailed godwit, which breeds in Western Alaska and winters in New Zealand and the coast of Australia.And it gets there by flying across the middle of the Pacific Ocean.
It's an up to 11 day non-stop flight during which they are in continuous powered flight.They don't soar, they don't glide, they are beating their wings continuously for 11 days.
burning up these enormous fat stores that they put on before they departed Alaska.They take off late August and early September and they make this incredible flight.
And the only way that they're able to do this is after more than doubling their weight, they're 55% fat by the time they leave. they get rid of their digestive system.
So having spent several weeks in frantic feeding in Alaska, they've gained as much weight as they can.Now their stomach and intestines, and to a lesser extent their liver and kidneys, dramatically shrink.
They atrophy in a matter of mere days, while at the same time their pectoral muscles, their chest muscles that power their flight increase by 50% in mass, and their heart mass increases by 30 to 50%.And they do this without exercise.
I would like to learn how to get ripped and buff like a bar-tailed god without exercise.Sign me up for that pill.
So at one point, you compare a Tour de France cyclist to a shorebird when it comes to sustained exercise.Share that with our listeners.I think that's a fascinating study.
Well, my colleague Tunis Piersma from the Netherlands, who's one of the world's great shorebird experts, has made the point that probably the human athlete at the peak of condition is a Tour de France cyclist.
And a Tour de France cyclist is operating at about four or five times his base metabolic rate.And he's only able to do that for a relatively limited period of time, certainly less than a day, and only with regular food and regular hydration.
On the other hand, a little semi-palmated sandpiper, one of the most common sandpipers we have in North America, like six inches long and weigh about an ounce, the population that breeds in the eastern and central Canadian Arctic will take off from the northeastern coast of North America, like the Canadian Maritimes, fly 3,300 miles nonstop across the western Atlantic all the way down to the northeastern coast of South America.
That's a four or five day flight.Again, no food or water or rest. and they're operating at nine or ten times their base metabolic rate, which itself is already higher than a person.
Their normal resting body temperature is about 140 degrees Fahrenheit.Spare me, please, the comparisons of birds to human athletes.The birds just leave the people in the dust, but there is one
similarity between these semi-palmated sandpipers coming out of the Canadian Maritimes and at least some Tour de France cyclists.Not naming names here.
The semi-palm sandpipers, when they're feeding in the mudflats of the Bay of Fundy, they preferentially seek out and feed on a tiny little crustacean called Corophyum.
And the reason they do that, we think, is because the corrophium are really high in omega-3 fatty acids, which supercharge the aerobic capacity of the bird's flight muscles.
They are basically juicing on performance-enhancing drugs, but doing it legally.
You know, Scott, there's many challenges these birds face as they're flying overhead and you devote quite a bit of your book to some of those challenges and just what man can do to improve the flight of these birds.
I wonder if you could address forest fragmentation because these birds do have what you call stopover sites and that's when things get difficult.
Right.Some of these birds like Bart-tailed Godwitch are able to make extraordinary long-distance migrations in one fell swoop.Most birds will stop along the way.
And in fact, even the bar-tailed godwit, coming back north in the spring, it veers way off to the west from New Zealand and goes to the Yellow Sea between China and the Korean Peninsula, where it stops, regrows its guts, eats dramatically, feeds up, and then takes and makes another 4,000 mile, 5,000 mile flight back to Alaska.
Without that stopover site where it can rest and refuel, it can't make that migration.And birds, You know, smaller birds have a tendency to make more stopovers on their migration north.
And the problem is there are just fewer and fewer places where they can find rest and relaxation and resources.In fact, scientists have actually categorized the places where birds stop. as fire escapes, convenience stores, or five-star hotels.
A fire escape is emergency habitat, where if the bird runs into a storm and is exhausted and wet, it's got a place.It doesn't matter how much food it has, it just needs a place where it can rest.
A convenience store, you can get something to eat there, but it's probably not going to be the best for you.You know, it's going to be Twinkies and junk food.
A five-star hotel is, for example, like some of these big bottomland swamp forests that we have along the Gulf of Mexico and Texas and Louisiana and Mississippi, which have lots of room and lots of food and lots of security for a migrating bird.
And just fewer and fewer of those places.
And of course, you mentioned forest fragmentation, but migratory birds come in all shapes and sizes and they use all kinds of habitat from mangrove swamps to open prairies and grasslands to coastal beaches, to hardwood forests, to conifer forests, on and on and on.
And so preserving enough of all of those different kinds of landscapes for all of these billions of birds that are moving back and forth from one hemisphere to the next is a real challenge.
And then you start to add in all of the other human-related pressures that these birds are facing.Climate change, obviously, is a huge one, changing weather patterns, changing the timing of the seasons.
Spring is coming earlier and earlier every year, and the birds are having a hard time keeping up with that because the timing of their migration is genetically encoded in their DNA.
Cats, I mean, we lose 4 billion birds in the United States every year to free-running house cats, both feral cats and free-running pets.It's the single biggest human-related cause of bird death.We lose another 2 billion to windows.
About a third of a billion fly into lighted skyscrapers in urban areas.Who knows how many are hit by cars?All of these forces together, they're all additive, they're all cumulative.
And, you know, you look at that, maybe it's not surprising that we've lost about a third of North America's birds in the last 50 years.
Almost 3 billion fewer birds today than when I was a wide-eyed 12-year-old sitting up on top of Hawk Mountain 50 years ago.
How do urban lights affect migration patterns?
Well, interestingly, I mean, and maybe not surprisingly, given that we know that birds evolved to navigate by starlight, not surprisingly,
urban light pollution has kind of a moth to the flame effect for migrating birds, and especially in the fall when most of the birds that are migrating are young birds on their first migration, these naive young birds, and they just get drawn into urban areas and
And that's a problem because, as I said, they fly into windows, they fly in particularly into lighted skyscrapers.
If you want an example of this, the tribute in lights every 9-11 at the southern tip of Manhattan, when they beam those two enormous beams of light into the night sky, that coincides most years with the peak of the songbird migration.
And in fact, they have to turn those lights off every 20 minutes, an hour or so in order to let the birds that are sort of disoriented and trapped in those beams of light disperse.So there's been a real push in recent years to get
particularly urban skyscraper owners, municipal leaders, but even folks in the suburbs of the country, just to turn off their lights during the migration season.We waste so much light in this society that's unnecessary.
It blanks out the night sky for us as well as birds.So turning out the lights makes a huge difference.The other thing we're realizing, I think, Bob, is that we can save a lot of birds that are going to get drawn into urban areas anyway.
by increasing and enhancing bird habitat in urban parks and green spaces.And this is not a difficult thing to do.And it's not something that even has to take away from human recreation in those parks.
But we know that big parks like Central Park in New York or Fairmont Park in Philadelphia, but even little pocket parks that are only a couple of acres can serve as a life raft, you know, continent wide for tens of millions, maybe even hundreds of millions of migratory birds.
I'm Bob Kustra, host of Reader's Corner.Today I'm speaking with Scott Weidensaul, author of A World on the Wing, The Global Odyssey of Migratory Birds.
You touched on it, but I just want to make sure our listeners hear this because in the book I think it's absolutely fascinating.I never gave it a lot of thought.
These birds, the map these birds are using, needless to say, doesn't look anything like the maps we use.They're using the map of the stars.Is that correct?
That's right.That's one of the things that they're using.Birds have a whole host of orientation and navigational cues that they're able to tap into, including a lot of senses that we're blind, deaf, and dumb to.So yes, most birds migrate at night.
That's why light pollution is such a problem.Even birds that are normally active in the daytime, like songbirds. And so, yes, on a clear night, they're using not the pattern of the night sky.
They're not looking up and saying, okay, the giant W is Cassiopeia, so that means I make a left.They're looking at the fact that part of the night sky does not appear to move.And of course, that's the part of the night sky around Polaris.
Everything else seems to rotate.All the other stars seem to rotate around Polaris.So that gives them their compass points, their cardinal directions. But they can also use extremely low frequency sound waves, infrasound.
Many birds can navigate using their sense of smell, especially seabirds.
Birds can use, you know, like daytime migrants like raptors and swallows use the position and movement of the sun and also a band of polarized light that moves across the sky and kind of in lockstep with the sun.They use that as an orientation cue.
But the most remarkable aspect of a bird's navigation is its magnetic sense.We've known for at least the last 150 years that birds can sense the Earth's magnetic field. You can disorient a bird by taking a little magnet to the top of its head.
But exactly how they sense the Earth's magnetic field has been a mystery.When I was in college in the 1970s, I did take an ornithology course before I dropped out.
We were taught that birds had little deposits of magnetic iron crystals called magnetite in their beaks or in their brain.And that the assumption was this function kind of like a little compass.
Well, it turns out those little deposits are not actually magnetite.They're not actually part of the bird's navigational system.They're probably connected to its immune system.
And the explanation for how a bird detects the Earth's magnetic field is just too weird for words. All the evidence now suggests a form of quantum mechanics called quantum entanglement.
This is the form of quantum mechanics that is supposedly going to provide us with unhackable quantum computers and faster than light communication.
But what it allows the bird to do, and we don't know what it looks like to the bird, but clearly they are able to visualize the bands of electromagnetic radiation that are radiating out from the Earth's core.
And this gives them essentially orientation along a north-south axis because the angle at which those magnetic fields are emerging from the Earth's surface, the angle changes the closer you get to the equator or the closer you get to the pole.
So that gives them their latitude, their North and South.What it doesn't give them is longitude.And we still don't understand the magnetic sense that allows a bird on an East-West access to determine longitude.
It seems like it is probably connected with what's known as the trigeminal nerve, which runs through the upper beak of the bird.Because if you experimentally sever that trigeminal nerve,
The bird can still orient north and south, but if you capture a bird, sever the trigeminal nerve, move it a thousand miles to the west and release it, it's not going to compensate for that longitudinal change.
It'll just say, oh, I just need to go north and off it goes in the wrong direction.But there's still a lot we don't know about all the ways in which a bird is able to sense the world and figure out how to find its way across.
Well, the lay reaction to this, when you look at the size of this bird, and my wife and I, by the way, help a hummingbird raise her two youngsters every year underneath the eave of our front porch.And we're watching now.
When you look at the size of them and you figure they've got to grow
and they'll leave at the end of august and then they're going to fly two or three thousand miles i mean it's just boggles the mind to think how could they stash all of what you just described into that little bitty brain that little bitty body unit it's a little bit if you look at a bird with a brain the size of a tic tac yeah
And then learn, I mean, different routes.I mean, they'll make the first flight on instinct.I mean, almost every bird, when it's migrating, it's not following mom and dad.It's not learning from an older bird.You know, it's entirely on instinct.
It's just baked into the DNA.But they make that trip the first time, and then they will learn. to take shortcuts, or they'll learn that such and such a backyard in New Mexico has a lot of feeders, and they'll hit that on the way south.
It's like, you know, you make the trip back and forth from Idaho to California a couple of times, you figure out where the good rest stops are, and what greasy spoons to avoid.
Birds do exactly the same thing, and they store it all in that tiny, tiny bird.
So I'd like you to tell us about eBird and how that has improved our ability to learn more about the challenges that these birds face.But before you answer that, I do want to give our listeners another tip.
If you're interested in birds at all, I use Merlin as an app on my phone. And what's frustrated me for years is that I would hear all this beautiful bird song on my hikes and I'd look up and I could never find the bird.
Every now and then they come down at my feeder, of course, but most of the songbirds don't feed at the feeder and they're way up in the top of the overstory to the tree and Merlin, you turn this free app on that comes out of Cornell University.
I think you can verify that, Scott.And I get the list of the birds that are at that moment singing near my phone.I've done it in the desert.I've done it in the western forest.I've done it in the midwestern forest.
It works every time and is seldom, seldom wrong.
Well, I'm here to tell you it works just as well in the forests of New England.There you go.Yes, it's the Cornell Lab of Ornithology, which is kind of your one-stop shop for anything having to do with birds or ornithology.
And I'm probably unseemingly proud, maybe is the way to put this, that the fellow that runs the whole Merlin operation, Drew Weber, is one of my former research technicians.He worked for me years ago on our CRL research. Brilliant guy.
But yeah, I mean, so what we have here, eBird, which of course is the world's largest observational, wildlife observational database, about 100 million sightings sent in by birders every year all around the world.
It's allowing us to visualize the distribution and movement and density of birds primarily in the Western Hemisphere at the moment, but increasingly around the world. at a level that would have been incomprehensible five years ago.
And it's a really good example of how big data with a capital B and a capital D are impacting our understanding of bird migration.
Because you layer that, you layer eBird data on top of Doppler weather radar data, which shows us exactly how many birds are migrating overhead, like how many birds per cubic meter of airspace are up there.
Again, the Cornell Lab of Ornithology, BirdCast.info is the website.BirdCast takes all of that real-time weather radar data from 140 weather radar stations across the U.S.and will show you exactly how many
birds are migrating over the lower 48 on any given night in spring and fall migration.They also have forecasts for where the migration is going to be good and what different parts of the country.
You can see these visualized maps based on weather and radar.We start layering all of these things together along with the tracking data that we're talking about.
And it gives us an almost second-by-second window into where and what numbers these birds are, what habitats they're using.
For example, the Doppler weather radar, if you look at just the very lowest beam of the radar that catches the birds just as they're emerging on their nighttime flights, well,
And where you get more birds emerging from the ground, those are places that are likely to be the most important for migratory birds.Those are really good stopover points.
And in fact, Dr. Jeff Buehler at the University of Delaware did a study for the Fish and Wildlife Service a couple years ago in the Northeast, looking at the most important areas based on weather radar data for migratory birds from Virginia up to Maine.
And a whole bunch of places popped out. the Green Mountains, the Adirondacks, the Pocono Plateau in Pennsylvania, Southern New Jersey, the western shore of the Chesapeake.
Those are places where we ought to be putting most of our scarce conservation dollars in terms of land protection and habitat restoration, because the birds are telling us that those are the most important places for them.
So all of these things together, not just giving us a better academic understanding of migration, but also showing us how and where we can take action to protect and restore migratory birds.
Now there is so much we can do and the place to start is with the book that helps us understand the challenges these birds are facing.
And frankly, what you learn about that, Scott, you've done a brilliant job of also showing us what we can do to improve the land and water that humans enjoy as well as the birds.
The book is, A World on the Wing, The Global Odyssey of Migratory Birds.Scott Wiedenthal is the author.He's joined us today here at Reader's Corner.Scott, thanks for the book.Thanks for this great interview.Really appreciate it.
Oh, Bob, it's been a real pleasure.Thank you so much.Great questions.You're welcome.Take care.
Reader's Corner is presented by Boise State Public Radio News.The engineer for today's show is Eric Friderici, with production by Joel Wayne.I'm Bob Kustra.
Please join me next week as we talk to today's leading writers about the ideas and issues that help shape our world at Reader's Corner.
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