Flight Paths E-Book

Rebecca Heisman

• Herausgeber: Swift Press
• Kategorie: Lebensstil
• Sprache: Englisch

Seitenzahl: 410

Veröffentlichungsjahr: 2023

Beschreibung

How and why birds navigate the skies, travelling from continent to continent — flying thousands of miles across the earth each autumn and spring — has continually fascinated the human imagination, but only recently have we been able to fully understand these amazing journeys. How did this revolution come about? Flight Paths is the never-before-told story of how an eccentric group of ornithologists, engineers and other pioneering scientists have harnessed nearly every technological development of the last hundred years to understand bird migration in detail - from where and when they take off, their flight paths and behaviours, their destinations and the challenges they face getting there. In this fascinating and compelling story Rebecca Heisman uncovers the secret history of an ornithological arms race that not only helped solve the mystery of bird migration using radar, radioactive isotopes, satellites and the humble aluminium band but has also given us much needed insight into how best to protect and conserve the bird life we cherish.

Leseprobe

SWIFT PRESS

First published in the United States of America by HarperCollins Publishers 2023

First published in Great Britain by Swift Press 2023

Copyright © Rebecca Heisman 2023

The right of Rebecca Heisman to be identified as the Author of this Work has been asserted in accordance with the Copyright, Designs and Patents Act 1988.

Designed by Kyle O’Brien

A CIP catalogue record for this book is available from the British Library

ISBN: 9781800752924 eISBN: 9781800752931

For #BirdTwitter, without whom this book wouldn’t exist;

and in memory of Bill Cochran, 1932–2022.

Contents

Introduction | Where Do the Birds Go?

One | A Bird in the Hand

Two | Looking and Listening

Three | Chasing Angels

Four | Follow That Beep

Five | Higher, Further, Faster

Six | Navigating by the Sun

Seven | You Are Where You Eat

Eight | The Feather Library

Nine | Vox Populi

Conclusion | Sky Full of Hope

Acknowledgments

Further Reading and Resources

Notes

Introduction

Where Do the Birds Go?

I used to think I knew a lot about bird migration.

After all, I’d studied zoology in college, collecting data on the behavior of robins and sparrows for class projects and volunteering to help survey bird populations and monitor nest boxes. After graduation I’d found work as a seasonal field assistant on ornithology research projects on the prairies of Saskatchewan and in the Australian outback. I’d even kept a “life list” for a time, documenting more than six hundred bird species that I’d observed on my travels. Eventually I ended up working for the American Ornithological Society (AOS), the world’s largest professional organization for scientists who study birds.

At AOS, a large chunk of my job was to publicize the research being published in its two venerable ornithological journals, which until recently were known as The Auk and The Condor (in 2021, these historic names were changed to Ornithology and Ornithological Applications). Instead of working in the field to help collect data, I spent my days at a desk reading cutting-edge migration research produced by others. I waded through scientific papers and exchanged emails with the researchers behind them as I translated their work into digestible blog posts, tweets, and press releases.

And for someone who thought I knew plenty about bird migration, I found myself being surprised an awful lot. Not just by what these scientists were learning—although that was fascinating, too—but by how they were learning it, the details in the sometimes-overlooked “methods” section of a scientific paper, where researchers spell out exactly how they produced their data. Despite my own background in ornithology, it was news to me that birds’ migration patterns could be studied with weather radar. Or by analyzing the hydrogen isotopes in their feathers. Or with tiny devices that used the movement of the sun to calculate location. How, I wondered, did we even figure out how to do any of this? Almost every branch of science, it seemed, had been co-opted in service of figuring out the answer to one question: just where it is that birds go when they disappear south over the horizon in autumn.

Humans’ curiosity about this goes back a very long time. Native American cultures seem to have figured out early that birds were flying away to distant locations when they vanished in the fall; Athabascan people in what is now Alaska, for example, have an old story about how Raven fell in love with a goose but had to part with her when fall arrived and she flew away over the ocean. European thinkers, however, took awhile to catch up.

Although some ancient Greek writers speculated that birds left for warmer locations, Aristotle threw things into confusion when he wrote his Historia Animalium in the fourth century BC. In it, he hypothesized that swallows hibernated in crevices in trees and that some winter and summer residents were in fact the same birds in different plumages—for example, that the common redstarts he saw in summer transmogrified into European robins when the seasons changed. Inspired by Aristotle, the Swedish priest Olaus Magnus suggested in the sixteenth century that perhaps swallows hibernated in the mud at the bottom of lakes and rivers, a misconception that persisted into the nineteenth century.

Perhaps the most outlandish idea, however, came from the English minister and educator Charles Morton. In the late seventeenth century, Morton, better remembered for writing a physics textbook that long remained in use at both Harvard and Yale, wrote a treatise in which he laid out his own fantastical theory of bird migration: they were simply flying to the moon. He estimated that if they could fly 125 miles per hour, it would take a flock of birds about two months to make the journey (although his approximation of Earth’s distance from the moon was short by about 25 percent). As ridiculous as this sounds today, Morton was writing at a time when it was popularly believed that other planets must be inhabited and no one realized that there was a crucial lack of oxygen in the space between them. Some of the things he intuited about the natural history of migration turned out to be more or less right. He speculated that birds may be spurred to move to new areas by changing weather and a lack of food, and he even noted that body fat might help sustain them on their journey.

Early naturalists could guess all they wanted, but the first truly concrete evidence of where birds disappeared to every year arrived in the form of an unfortunate stork shot outside a German village in 1822. When the hunter went to pick up his prize, he must have been astonished to see that it had a massive spear impaled clear through its neck, which it had apparently been carrying around with it for some time. A German newspaper eventually analyzed the wood in the spear and its iron tip and concluded that it must have originated somewhere in Africa. Dubbed the Pfeilstorch (German for “arrow stork”), the bird was taxidermized—spear and all—and is still on display in a natural history museum in Rostock, Germany.

Since it had last departed Germany, the Pfeilstorch had not hibernated, transformed into a different species, or gone to the moon. Instead, it had been to Africa. Birds, it seemed, were traveling between continents.

Before we go any further, I should probably talk about what exactly bird migration is and how it came to be. Migration is simply the seasonal movement of animals between regions. Birds can be “permanent residents” that opt out of migration entirely to spend their whole lives in one place, short- or medium-distance migrants that move anywhere from a few miles up or down a mountainside to a few hundred miles, or—like most of the birds in this book—long-distance migrants, whose journeys span entire continents. Birds make these treks to take advantage of shifting resources at different locations throughout the year, chasing booms in the availability of insects and other key foods and the right conditions to nest and raise babies. The urge to migrate when spring and fall arrive can have a range of complicated triggers including changes in weather and day length as well as genetic programming. However it happens, though, there’s a lovely German word that ornithologists use to describe this feeling that comes over birds: Zugunruhe, which literally means “movement restlessness.”

Scientists have come up with two competing theories to explain how long-distance migration might have originated. The “northern home” hypothesis supposes that migrants are descended from birds that evolved at northern latitudes and eventually started to push farther and farther southward in the winter in search of milder climates. The “southern home” hypothesis is, just as you’d expect, the opposite—the idea that migrants started out as tropical birds looking north for better breeding grounds.

Analyzing the evolutionary family tree of long-distance migrants in the Americas suggests that the northern-home scenario was probably more common, and that some birds that live in the tropics year-round today are in fact the descendants of northern-home migrants that eventually began sticking around on their wintering territories permanently. Either way, striking out in search of better habitats made the ancestors of today’s migrants more successful, they passed their wanderlust on to their offspring, and the evolution of long-distance migration was the result.

To make their epic voyages, birds rely on a range of navigation techniques. Genetic hard wiring seems to play a role, but migrating birds can also adjust on the fly (so to speak) by taking cues from the appearance of landmarks below and the orientation of the sun and stars above. Birds can even sense Earth’s magnetic fields, through an inscrutable mechanism that recent research suggests may have something to do with quantum physics (!).

In the spring of 2020, vast new numbers of people discovered the magic of migration for themselves. Bird-watching, it turned out, was the ideal hobby for pandemic lockdowns. Visits to websites listing local bird sanctuaries and downloads of bird ID apps soared during those months. Retailers couldn’t keep up with the increased demand for bird feeders and birdbaths, and people flocked (forgive the pun) to the Facebook groups of local bird-watching clubs.

The appeal was clear. You can watch birds almost anywhere, including, literally, your own backyard. The equipment needed to get started is minimal, and especially early on, when almost every species you learn to identify is new to you, it can provide a sense of novelty that’s otherwise sorely lacking when you’re stuck at home. And birds, after all, had never heard of coronavirus. Entering their world, if only for a little while, gave us a chance to forget what was going on in our own, and that first COVID wave in the United States happened to coincide with one of the most tantalizing phenomena in the natural world: spring migration. We might have been stuck at home, but birds of all shapes, sizes, and colors were traveling thousands of miles, returning from wintering grounds in Central and South America to their summer homes where they would find mates, build nests, and raise babies.

I was one of the many people paying closer-than-usual attention to the waves of migrants arriving that spring, enjoying seeing the cold and silent woods of my local birding patch filling anew with color and song. But like many, I was experiencing profound upheaval in both my personal and my professional life during those months. In need of a change, I decided it was time to turn some of what I’d learned at the American Ornithological Society into the proposal that became this book.

Many wonderful books have already been written on what migrating birds do and how they do it, but dig a little deeper, and you’ll find there’s another story here that’s equally fascinating. We live in an era when you can go online and track the latest movements of an albatross via satellite nearly in real time, or download data on exactly how likely a given migratory species is to be present at any point on the globe, during any week of the year. How did we get from the Pfeilstorch to here?

The answer involves a sprawling group of ornithologists, engineers, and other scientists who’ve harnessed nearly every major technological development of the last hundred years in service of their quest to document bird migration in ever-greater detail, along with the legions of everyday bird-watchers documenting their observations of the world around them. In this book, I’ll take you through techniques ranging from the origins of scientific bird banding to the latest breakthroughs in high-volume genetic sequencing. Along the way, I’ll introduce you to some of the colorful characters who’ve made the science work—and, of course, the amazing birds whose journeys they’ve helped reveal. Whether you’re a casual bird lover, a dedicated amateur ornithologist, or even a history of science buff looking for a fresh perspective, there is something in these pages for you.

If you’ve followed environmental news at all in recent years, you know that migratory birds are in trouble. But to save them, we need to know them. The people in these pages are the ones making that happen.

One

A Bird in the Hand

The summer I turned nineteen, I spent several weeks volunteering at Long Point Bird Observatory (LPBO), on the Canadian shore of Lake Erie. I’d just finished my sophomore year of college, where I was majoring in zoology, but this was my first hands-on experience with wildlife outside school. Officially, I was there to help with a decades-long research project on breeding tree swallows, which required monitoring hundreds of nest boxes and recording the birds’ progress as they built nests, laid eggs, and raised babies. But in the mornings, I also got to participate in the work LPBO was best known for: bird banding.

Seven days a week, weather permitting, a dozen or so dedicated volunteers would rise before dawn to open the mist nets, lengths of fine nylon mesh strung like volleyball nets between metal poles. They were hung along paths through a small woodlot behind the building that housed researchers and volunteers, where birds would blunder into them as they went about their own morning routines, searching the little patch of forest for seeds or insects to eat. Mist nets secure birds in place without injuring them, and every twenty minutes we would walk along the nets to check for captured birds and then go through the delicate process of extracting them, working the loops of mesh free from their feet and wings.

I was there in time for the tail end of spring migration season, and every walk to check the nets felt like Christmas morning as I peered ahead to see what species we’d snagged. Would we spot the flame-orange throat of a Blackburnian warbler glowing in the net like an ember? The dapper black-and-white stripes on the face of a red-breasted nuthatch? Would a local cardinal have blundered in, ready to latch painfully onto the web of skin between my index finger and thumb with its massive orange bill? Extracting the birds was tricky work, and I never became very proficient at it. Woodpeckers in particular were notorious for sticking out their long, sticky tongues, which help them rake tiny insects out of bark crevices and wrap around the back of the birds’ skulls when not in use, and getting them hopelessly entangled. But I loved patrolling the nets in the cool morning air, taking in the damp woodsy smell and the golden morning light filtering through the trees and the sound of birdsong.

Once they were out of the net, we would gently place the birds in cloth drawstring bags and carry them back to the banding lab. There, an experienced bander identified the species and used a special pair of pliers to close a numbered aluminum band around the bird’s leg, reading out the number on the band to whoever was taking notes. A few moments were all it took to record a range of data about each bird, including its age and sex, some size measurements, and the amount of fat stored under the translucent skin of its belly, crucial fuel for the remainder of migration.

Weighing was always the last step. We weighed the birds by putting them headfirst into a small tube and then placing bird and tube together on an electronic scale, the immobilized bird’s feet sticking comically out of the top. Finally, the bird was released directly from the tube via an open window in the lab. Watching a wren or sparrow or warbler wriggle out and shoot toward the trees, free again after its short interlude with us, was electrifying. Some of the birds we caught would be breeding nearby, but others still had a long journey ahead of them to reach nesting grounds in Canada’s boreal forests.

A few of the birds we banded—not many, but a few—would be captured again, here or somewhere else, and the numbered bands would identify them, letting scientists track where they’d been and what condition they’d been in. I didn’t fully appreciate it at the time, but the mornings I spent at the banding station that summer made me part of a scientific tradition stretching back more than a hundred years.

Why Band Birds?

Since its banding program began in 1961, the Carnegie Museum of Natural History’s Powdermill Nature Reserve in southwestern Pennsylvania has banded more than 700,000 birds. Here are the recorded fates of a few:

Winter 1969–1970 or 1970–1971: A Swainson’s thrush banded on September 24, 1966, is killed with a blowgun by an indigenous Peruvian roughly twenty-five miles south of the border with Ecuador.

October 8, 1971: A Traill’s flycatcher banded on September 12 of the same year is found alive inside a bank in Belize City, British Honduras (now Belize).

May 22, 2001: A scarlet tanager identified as a “second year” bird when it was banded on June 21, 1990, is found dead near Houston, Texas. Just shy of twelve years old when it died, this bird holds the current longevity record for its species.

October 10, 2014: A ruby-throated hummingbird banded on September 18 of the same year is recaptured at a banding station in Lake Jackson, Texas. The distance between Powdermill and the Lake Jackson banding station is 1,425 miles, meaning the bird traveled an average of 65 miles every day for three weeks.

Powdermill is the longest-running year-round banding operation in the United States, and I knew that if I wanted to find out more about bird banding (aside from my own personal experience as a nineteen-year-old), they would have the answers. Annie Lindsay, the current manager of the bird banding program, started volunteering at Powdermill in 1999 when she was in high school, fell in love with bird banding, and never left. On top of her duties at Powdermill, she’s also a PhD student, using banding data to look at how climate change is affecting the length of birds’ wings.

Needless to say, Lindsay is busy, but she was kind enough to let me call her up and ask her all my bird banding questions on her one day off a week during fall migration.

The first thing I wanted to know was what exactly being the manager of such a large banding program takes. Unsurprisingly, it’s no small job. Lindsay is in charge of making sure things are running smoothly at the banding station, coordinating with all of the volunteers and seasonal staff to confirm there are enough people there each day to be able to handle the volume of birds that they’re expecting to get. “I’m also the person who trains new volunteers and field techs,” Lindsay said, “and I process the birds,” meaning she bands and measures them after they’re removed from the nets.

Banding birds makes it possible for scientists to tell individuals apart; without a numbered band to go by, one robin or blue jay looks much like another. (Scientists who want to study the behavior of individual birds over a small area often add unique combinations of colored bands alongside the aluminum band so that, say, yellow-yellow-green can easily be distinguished from blue-yellow-yellow through binoculars.) In the United States, those bands are issued, and the resulting data archived, by the U.S. Geological Survey (USGS) Bird Banding Laboratory (BBL). As the Bird Banding Laboratory’s website explains, “When banded birds are captured, released alive, and reported from somewhere else, we can reconstruct the movements of the individual bird.”

Not just anyone can legally capture and band a bird. The Bird Banding Laboratory only issues permits to people who have a specific research project in mind and have had training on how to do it safely, without injuring the bird. Aspiring permit holders submit a résumé of their past (supervised) bird banding experience and training along with their research plan and other information.

Those strict requirements help ensure that banding is overall very safe for birds. Although there have been a few reports over the years of metal bands causing leg irritation, the vast majority of problems that do arise come from human error when extracting birds from nets and traps, and even that is very rare. “Bird banders operate under a set of ethics, and our very first priority is the safety and well-being of birds,” Lindsay said. Data from banding stations in the United States and Canada shows that for every thousand birds that are captured in mist nets, fewer than six suffer any sort of injury.

Mist nets, the primary tool banders use to capture birds, are usually about twelve meters long and two meters high, “made of really fine mesh that almost disappears if there’s some nice vegetation behind it,” Lindsay explained. Interspersed with the fine, loose mesh are heavier, tauter horizontal lines called shelves, which create pockets. “As the birds move through the habitat, they hit the net and drop into the pocket, and they’re held there gently until someone can come around and extract the bird from the net.”

Bands come in a range of sizes to perfectly fit every bird, snug enough to not slip over the bird’s “ankle” and fall off but loose enough to spin freely and not constrict the bird’s leg. There are tiny hummingbird bands that have an interior diameter about the width of a grain of rice and are stored on safety pins, and bands roomy enough to wear on your thumb for big birds like pelicans, swans, and eagles. A few birds, such as cardinals, receive special stainless-steel bands instead of aluminum; a cardinal’s massive orange bill is powerful enough to tear off an aluminum band. As I discovered that summer at Long Point, getting bitten by a cardinal hurts.

The percentage of banded birds that are ever heard from again—recaptured at another banding station, spotted by a bird-watcher able to make out the numbers on the band, found dead, or shot by hunters—is tiny. According to Bird Banding Laboratory staff, it ranges from around one in ten for ducks and geese to one in four hundred for songbirds. But the BBL distributes about a million bands every year, and those small percentages add up.

And banding is useful for studying much more than just migration. When I asked Lindsay what ornithologists can learn from bird banding, she almost didn’t know where to start. “There’s so, so much,” she said. Banding birds can help scientists figure out how long birds live, how large their populations are, how they behave when defending a territory and raising young, and much more. Banding also has a special role in the management of waterfowl populations, because it helps wildlife authorities set harvesting limits for ducks and geese; there are even special “reward bands” that hunters receive a small cash reward for reporting, to help calculate the chances that someone who shoots a banded bird will report it. But banding got its start with ornithologists looking to the sky and wondering where the birds were going, and it’s helped us answer that question, too.

Banding records, for example, helped scientists track how the migratory behavior of house finches changed after they were introduced into eastern North America in the 1940s. This familiar backyard bird, which resembles a sparrow that dipped its face in red paint, is native to the western United States, where only a tiny fraction of individuals move around between seasons. When a population became established in the East, however, their behavior changed quickly. Two birds banded north of New York City in 1959 turned up in the Philadelphia area and then, the following spring, back in the spot where they were originally captured, showing they’d made at least a short round-trip.

And they didn’t stop there. In 1998, the researcher Kenneth Able analyzed all the available bird banding data up to that point on house finches captured in the eastern United States and Canada and later reencountered. He showed that within twenty years of the birds’ introduction in the East, between a quarter and half of all house finches in the eastern population were migrating each year, despite being descended from birds that were almost all homebodies, and the number of birds that were migrating and the distance they were traveling was continuing to increase, with some flying all the way to Florida and the Gulf Coast in search of a mild winter climate. In fewer than sixty generations, Able suggested, the different pressures the birds were subjected to in their new habitat had led to the rapid evolution of migratory behavior.

Banding records also provided the first hints that something strange and wonderful was going on with the migratory route of a tiny bird called the blackpoll warbler. These birds (whose name comes from the black caps on the tops of their heads) nest as far northwest as Alaska, and to get there from their South American wintering grounds in the spring, they make a crossing to Florida and fan out from there. The obvious assumption would be that they do the reverse in the fall, but in 1970 the ornithologist Ian Nisbet pointed out that this didn’t line up with what bird banding stations were actually observing every autumn.

If the birds headed south via the same route they took north, banding records from the East Coast should have shown their progression south as the fall migration advanced. Instead, when Nisbet analyzed the records, he was surprised to find that blackpoll warblers were “progressively less numerous” at banding stations farther and farther down the coast in the fall. In Florida, capturing one in the fall was actually quite rare. Nisbet suggested that the birds were bypassing the region entirely in the autumn and doing something that seemed impossible for a bird that weighs about as much as a ballpoint pen: flying directly from New England to northern South America, crossing fifteen hundred miles of open ocean.

It would take another four decades and a tracking device based on navigation principles dating to the Renaissance to prove Nisbet right. But long before any of this research could occur, someone had to have the idea to put tiny bracelets on birds and see what happened.

Banding’s Origin Story

John James Audubon, namesake of the Audubon Society, is often credited as the father of bird banding. In his autobiography, he described tying silver threads to the legs of five eastern phoebe nestlings in Pennsylvania in the spring of 1804, when he was nineteen years old—the same age I was during my summer at Long Point.

“These they invariably removed,” he wrote, “either with their bills, or with the assistance of their parents. I renewed them, however, until I found the little fellows habituated to them; and at last, when they were about to leave the nest, I fixed a light silver thread to the leg of each, loose enough not to hurt the part, but so fastened that no exertions of theirs could remove it.”

The following year, as he told it, he spotted two phoebes bearing his silver threads on the same property, returned after their annual migration. Audubon had demonstrated for the first time that migratory birds return to the area where they were fledged. Or so he said.

It turns out that young Audubon was actually in France at the point in the spring of 1805 when he claimed he’d resighted his marked phoebes. And modern studies have found that only 1 to 2 percent of eastern phoebes return to the site where they were raised to breed, making his claim that two out of his five birds returned home extraordinary. Matthew Halley, the biologist and historian whose sleuthing uncovered these discrepancies, speculates that Audubon probably did attach the threads to the nestlings’ legs and just made up the bit about seeing them again the next year, part of an apparent habit on Audubon’s part to embellish the occasional fact in ways “favorable to his legacy.” America’s most famous ornithologist, apparently, liked to stretch the truth.

But even if Audubon was guilty of employing some alternative facts when he wrote his life story, the idea of marking individual birds to learn more about their movements eventually caught on. In the 1880s, a naturalist named Ernest Thompson Seton marked the breasts of snow buntings on his farm in Manitoba with printer’s ink to see whether the same birds stuck around all winter. (Apparently not, because he never saw his inked birds again. Seton would go on to greater fame as one of the founders of the Boy Scouts of America.)

The scientific use of metal bands originated in Europe in 1899 with a Danish ornithologist named Hans Christian Cornelius Mortensen, who worked first with starlings before moving on to ducks, storks, and birds of prey. Early bands like Mortensen’s often had the initials of the bander or location engraved on them for identification.

Banding (known as “ringing” in Great Britain) quickly took off both in Europe and elsewhere, and in the United States the story picks up with Leon J. Cole. Cole was born in 1877 and raised in Albany, New York. Although a “city boy” in his youth, “L.J.” nevertheless developed an early interest in plants and animals. He spent his summers working on farms before going off to college, and eventually he received a bachelor’s degree in biology from the University of Michigan and a PhD in zoology from Harvard.

While he was a student in Michigan, Cole was inspired by a U.S. Fish Commission project releasing live, tagged fish and asking fishermen to report them as a means of learning about their movements. At this point, Cole had never heard of either Audubon’s (questionable) experiment with phoebes or Mortensen’s efforts in Europe, but he wondered if something like the fish tagging program might be possible with birds. In 1901, at the age of twenty-four, he gave a talk to the Michigan Academy of Science titled “Suggestions for a Method of Studying the Migrations of Birds.”

“It is possible such a plan might be used in following the movements of individual birds,” he said, “if some way could be devised of numbering them which would not interfere with the bird in any way, and would still be conspicuous enough to attract the attention of any person who might chance to shoot or capture it.”

For six years, it remained just an idea. But in 1907, Cole became a zoology instructor at Yale University, where he conducted research on the genetics of pigeons. It was there, as a member of the New Haven Bird Club, that he finally got the chance to put his plan into action.

By now, Cole was aware that he wasn’t the first person to think up the concept of bird banding, having heard about Audubon’s and Mortensen’s work. He didn’t get to be the first person to actually try out bird banding in the United States, either; two others had beaten him to it since his original proposal in 1901. In 1902, a Smithsonian scientist named Paul Bartsch had experimented with banding young black-crowned night herons in the Washington, D.C., area, one of which turned up dead in Cuba two years later, the first long-distance banding “return” in North America. And in 1904, P. A. Taverner of Detroit distributed about two hundred aluminum bands to correspondents via a notice he placed in The Auk, the journal of the American Ornithologists’ Union (AOU). One of Taverner’s bands was used in Iowa to tag a northern flicker (a type of woodpecker) that was later recovered in Louisiana.

But Cole had grander ambitions for American bird banding. He realized that for the data collected to really be useful, some sort of centralized record keeping would be essential, rather than a hodgepodge of small individual efforts. (In one of his early papers on the subject, he noted the recovery of two ducks wearing bands inscribed with the initials TJOD; who or what TJOD was, no one ever figured out, making their recovery meaningless for science.) Toward that end, in the winter of 1907–1908 Cole and his New Haven comrades developed a system using numbered aluminum bands stamped with the club’s mailing address, along with standardized forms for recording information about each banded bird.

The number of birds tagged that first spring was “disappointingly small”; the plan was that club members would carry bands with them on their field trips and simply use them whenever the opportunity arose, primarily on baby birds still in the nest, but apparently “the chief interest of the field workers [was] along other lines.” Cole, however, was undeterred, and in 1908 the New Haven Bird Club scaled up its efforts under his direction. Now using bands stamped “Notify The Auk, New York,” it distributed around five thousand of them to ornithologists around the country.

About one thousand of those bands were used, and by the time Cole reported back to the American Ornithologists’ Union in December 1909, 3 percent of the banded birds had been “heard from since.” The most commonly banded bird, he reported, was the American robin, and their first “return” was of a robin banded in Rhode Island in 1908 and “taken” (presumably shot) the following spring in the same vicinity. None of the recovered birds showed any signs of harm from being banded.

Cole and his colleagues received some interesting letters from people who found their banded birds. Here’s one he reproduced in his 1922 account of this work, sent with a report of a banded night heron, with the original spelling, grammar, and capitalization preserved:

Gentlem dear sirs Your bird was shot here to day by me Albert Bailey for which I was more than Sorry when I found it had a ring on. I took it for a Hawk as It flew several times over my yard as I thought after chickens and Gentlemen all I can say that I am sorry If I did wrong In so doing and also beg Pardon.

Yours with Rees, Albert Bailey

Managing this expanded banding program while also teaching zoology at Yale proved a bit much for Cole to handle, though. Distributing bands far and wide “increased greatly the burden of correspondence, the difficulties of securing bands, and of obtaining funds to meet necessary expenses,” he wrote in 1922. The correspondence and record keeping “fell entirely to myself and had to be conducted without clerical assistance,” which, as he mildly put it, “grew to be a considerable burden.” Cole and his bird club buddies were even making most of the bands themselves, cutting up sheets and tubes of aluminum and stamping the bands with the numbers and contact information before sending them out.

Keeping up with the bird banding program on his own wasn’t going to be sustainable, and on December 8, 1909, Cole gave another presentation on his efforts so far to an American Ornithologists’ Union meeting in New York City in which he pleaded for the establishment of a formalized, permanent organization to oversee bird banding in the United States. At dinner that night, the American Bird Banding Association was formed, with Cole as its president.

As Cole’s career in the new field of genetics took off, however, his involvement in bird banding faded. In April 1910, Cole moved from Connecticut to Wisconsin to head up the University of Wisconsin’s newly formed Department of Experimental Breeding, the forerunner of its genetics program. He muddled along as best he could with the American Bird Banding Association for one more year until, about to leave for a summer in Europe, he had to face the fact that someone else would need to take over. He arranged for the Linnaean Society of New York City, an organization of professional and amateur naturalists founded in 1878, to take over for the AOU in overseeing the association, and Cole bowed out. This arrangement lasted until 1920, when bird banding became the responsibility of the federal government’s Bureau of Biological Survey, forerunner of the U.S. Fish and Wildlife Service (USFWS).

When the federal government took over the oversight of bird banding in 1920, the fledgling North American Bird Banding Program was headed up by the ornithologist Frederick C. Lincoln, who would hold the job for more than twenty years and become a legend in the field for his work with waterfowl banding records. Leon Cole, on the other hand, never really returned to his own initial interest in bird migration. Unfortunately—but perhaps unsurprisingly, for a scientist working in the early twentieth century and running a Department of Experimental Breeding—Cole later became involved in another field: eugenics.

This movement, which advocated for improving the human race through selective breeding, found broad support among American biologists, sociologists, politicians, and others in the first half of the twentieth century. Today, though, it’s impossible to view it as anything but the basest racism dressed up in pseudoscientific clothing. American eugenicists successfully lobbied to severely curtail immigration from nonwhite countries and pass antimiscegenation laws to prevent interracial marriage. Hitler drew inspiration from the American eugenics movement when hatching his plans for what became the Holocaust. Science, as history has shown time and again, can all too easily be misapplied by humans with prejudices. Cole gave speeches advocating for the “permanent segregation” of “defectives and cripples” to prevent them from breeding and passing on their inferior qualities and acted as a scientific consultant on the eugenic benefits of birth control.

Today Cole is mostly remembered neither for his involvement in bird banding nor for his support of eugenics, but for his work on the genetics of pigeons, work he began at Yale and continued in Wisconsin. Late in life, he mentioned to his friend Robert McCabe that he’d always wanted to be named a fellow of the American Ornithologists’ Union—a special honor conferred upon members for their “exceptional and sustained contributions to ornithology.” McCabe put together the nomination paperwork and sent it off.

But they never heard anything back. “What happened, I never knew, but the AOU turned him down—forgotten even by the enlightened and those who should have remembered,” wrote McCabe. “[His] disappointment was obvious, but never discussed between us.” It was 1946, the year of the Nuremberg trials, and the world was becoming aware of the full horrors of the concentration camps. I’d like to think that Cole’s more unsavory interests had caught up with him at last.

Sparrow Traps and Mist Nets

Cole and his contemporaries were mostly putting bands on baby birds that hadn’t left the nest, simply because they were the easiest to catch. Safely trapping adult birds to band them was a challenge that took some time to unravel.

One of the first to tackle it was a rakish Canadian named Jack Miner, or “Wild Goose Jack.” After establishing a waterfowl sanctuary on his property in Ontario in the opening years of the twentieth century, he became determined to figure out where the ducks and geese that passed through every year were headed. Eventually, he devised a trap for Canada geese that consisted of a canal connecting two ponds with a trapdoor at either end and caught his first goose in the spring of 1915.*

All that was known at that point about the migration of Canada geese, his son Manly (who carried on his work) later wrote, “was that they went north, and the settler in the most northern point in Canada always reported that they went still farther north.” But that October, Miner received a letter from a representative of the Hudson Bay Company, informing him that his banded goose had been killed by “an Indian” in August in the vicinity of Hudson Bay, where it had been nesting. Miner would go on to band thousands of geese and ducks, vastly improving ornithologists’ understanding of their routes to and from their Arctic breeding grounds.

Catching smaller birds, like songbirds, required a different approach. The first person in the United States to attempt it on a large scale was a lawyer from Ohio. “Never of very rugged constitution even from early youth,” according to later accounts, Samuel Prentiss Baldwin had retired from practicing law due to poor health in 1902, when he was only thirty-four. He pursued other businesses, but he also took an interest in the birds on his farm outside Cleveland.

Around 1913, he became determined to eradicate house sparrows from the property. Introduced from Europe about sixty years before, this species had quickly spread across North America, competing with native birds for food and nest sites. To get rid of them, Baldwin used a contraption called a “Government Sparrow Trap,” promoted by the U.S. Biological Survey for getting rid of the pesky invasive sparrows. Consisting of a wire mesh cage into which birds were lured with a bait of grain, the trap apparently did its job. “The Sparrows were destroyed in large numbers, and the farm pretty well cleared of them, greatly to the comfort, evidently, of the native birds,” wrote Baldwin, “for it was very noticeable that, as the Sparrows decreased in number, the native birds greatly increased.”

The traps captured the birds alive; the “destroying” had to be carried out separately. And when Baldwin heard about the recently formed American Bird Banding Association, he began to view them in a new light. As the number of house sparrows on his farm decreased, more and more native birds had been showing up in his traps, and in 1914 he began banding them.

The photos included with his treatise on his trapping and banding efforts, published by the Linnaean Society of New York in 1919, show Baldwin operating traps and handling birds while wearing a bow tie and a dapper boater hat. By that time, he had banded nearly sixteen hundred birds and had received outside reports about the fates of three, including a robin that turned up in South Carolina. He’d also devised some additional trapping methods of his own, such as using trapdoors to capture birds in nest boxes.

Some birds returned to his baited traps again and again in search of grain. “One learns to know the characters of certain individuals, as I came to know a certain White-throated Sparrow, who always identified himself by fighting and biting my fingers,” he wrote, “and another White-throat, who distinguished himself as a squealer.”

Baldwin died in 1938 at the age of seventy. Variations on his trapping methods continued to be the standard for bird banders in the United States until the introduction in the 1950s of the piece of gear I helped use during my summer at Long Point: the mist net.

Fine nets made of black silk, strung between bamboo poles, had been used by the Japanese since the seventeenth century to catch small birds as they made their way from breeding grounds in Siberia and northeastern Asia to wintering grounds in southern Japan. These original mist nets weren’t part of any scientific research, however; the birds caught in them were eaten. Similar nets were used for the same purpose in parts of southern and eastern Europe, and American ornithologists had stumbled across immigrants using them in California as early as the 1920s. But mist netting didn’t really start to take off with scientists in the United States until 1947, when Oliver Austin, a Harvard-educated ornithologist who headed up wildlife management in Japan under the Allied occupation following World War II, described them in one of his reports from the island nation.

Mist nets soon caught on in the United States with bat researchers as well as ornithologists, although figuring out exactly how best to use them took some trial and error. In 1950, the Louisiana State University zoologist George Lowery (remember that name—Lowery and his students pop up repeatedly in the history of migration research) gave the mammalogist Walter Dalquest three Japanese silk mist nets to try out in his work inventorying bat species in the Mexican state of San Luis Potosí. In his account of the attempts that followed, Dalquest never gives the name of the Mexican field assistant whose suggestions about net placement led to their catching their first bats. In addition to all the awkward crashing around in the brush at night necessary to net the night-flying animals, however, Dalquest described an incident in which a “wandering cow” blundered into one of the nets and entangled its horns. “The net had slipped from its supporting poles and the cow, with my men after it, had crashed off through the brush,” wrote Dalquest. After they finally recovered the net, “the departing cow was warned with a load of dust shot never to return.”

Once scientists got the hang of them, the advantages of mist nets over baited wire traps became obvious. For one thing, the only birds attracted to traps baited with grain were birds that ate grain; mist nets could ensnare a much richer variety of species, including the many that preferred insects. For another, as long as the person carrying out the netting knew what they were doing, they seemed to be safer for the birds themselves. Birds in hard-sided traps were prone to injure themselves by flapping ceaselessly against their restraints, and because traps were typically checked less frequently, birds captured in them were often vulnerable to passing predators.

Mist nets aren’t the only method used today to capture birds for banding; cannon nets and rocket nets fire large nets out to ensnare groups of shorebirds on beaches, for example, and descendants of Baldwin’s baited traps and nest box trapdoors are still used in some situations. But modern mist nets, which are made of nylon or polyester and come in a range of mesh sizes for use with different bird species, have become inseparable from the practice of bird banding.

No matter how a bird is caught, however, the real magic begins when someone gets the chance to take an intimate look at it and see what they can learn.

The Bird Banding Laboratory

“Having a bird in your hand—it just changes everything.” Tony Celis-Murillo’s voice turns warm and soft as he talks about what it’s like to band a bird. “Learning the details of identification and things like that—it’s great with binoculars, but still it’s far away. When you have it in your hand, and you can look at the details, it just engages you right away.”

When we spoke in the fall of 2020, Celis-Murillo was the acting chief of the USGS Bird Banding Laboratory, filling in for the permanent chief, who retired in 2019. A native of Mexico, Celis-Murillo volunteered with fish and mammal biologists as an undergrad at the Universidad Autónoma del Estado de Morelos, but it was when he got his first taste of bird banding that he fell in love. Much of his research on birds’ song and behavior has relied on marking birds with colored bands to make individuals easily identifiable as they go about their lives.

“It was so cool doing those observations, spending hours in the field and seeing, oh, red-green-yellow-aluminum is fighting with green-green-yellow-aluminum. You start to get to know everyone, and you talk about the color combinations like names,” he says. “Oh, remember green-green-yellow? Yeah, he’s always a mess!”

The Bird Banding Laboratory has been shuffled among various federal agencies over its hundred-year history, becoming part of the USGS after a reorganization in 1996. (It jointly oversees the North American Bird Banding Program with its Canadian counterpart, the Canadian Bird Banding Office.) While the actual process of putting a band on a bird has changed little in the last century, the technology used to collect and archive the resulting data has gone through a series of monumental shifts.

For most of the BBL’s history, bands were inscribed with a mailing address, just as Cole’s were when he began his first centralized distribution of bands. People who found a banded bird (usually members of the public stumbling across a dead bird, or hunters shooting a banded duck or goose) would write to the lab to report their observation. In the 1990s, the BBL switched to bands stamped with a toll-free phone number and started staffing a call center to receive reports. Either way, anyone who submitted a report would receive a certificate of appreciation with details about their bird, including where and when it was banded and its approximate age at the time.

“We have stories of people who have walked in the forest of Central America for a week to find the closest post office, because they wanted to know where this bird came from and what the band meant,” says Celis-Murillo. The certificates of appreciation distributed by the BBL engaged the imaginations of thousands of people. Imagine learning that the tiny gray-and-yellow warbler that turned up dead in your driveway in Texas had been captured and tagged by scientists two years before in Ontario, Canada, and had likely been on its way to South America when felled by bad weather and exhaustion: no matter how sad you felt for the bird, your discovery made you part of a network of researchers studying one of the most amazing natural phenomena on the planet.

In 2006, the BBL launched the website reportband.gov, and bands issued today bear a URL instead of an address or phone number. About 100,000 “encounter reports” are submitted each year, and the number is growing. In addition to people finding and reporting dead banded birds, there are more people taking up bird-watching as a hobby than ever before, and many of them carry powerful spotting scopes and cameras into the field that let them make out band numbers without the need to recapture birds. “It seems like we’re going to achieve this countrywide support of eyes and hands out there who are contributing to learning more about birds,” says Celis-Murillo.

Because bird banding also serves as the basis for many other, higher-tech bird research techniques, BBL staff also have to keep abreast of the latest cutting-edge methods for tracking birds—even as they remain the caretakers of the oldest method of all.