Immigrant Birds

(Birds of Passage – History, Science, Politics)

Where do birds go in the winter? The answer seems obvious now: They migrate to warmer climates. But how did people learn that birds undertake these regular journeys in the first place? Migration, after all, is one of nature’s most stunning phenomena. It defies credulity to realize that a tiny swallow flies 6000 miles in its annual pilgrimage, or that a common redstart flies nearly 4000 miles from Europe to the Sahel. The Arctic tern holds the record, flying nearly 44,000 miles every year.

The history of bird migration studies is a history of curious theories, ingenious inventions, and international cooperation. Tracing this history yields fascinating glimpses into the beginnings of science and environmentalism, the cultural importance of birds, and the surprising political valences of animal migration.

*** Competing Theories ***

The ancients noticed that swallows, redstarts, cuckoos, and other common birds disappeared each winter and returned in the spring, but it was not obvious to them what was going on. In his History of Animals, Aristotle offered migration theory as one of several explanations for the seasonal disappearance of birds. He also discussed alternative theories, including hibernation. Some birds, like swallows, he wrote, “go into hiding” each winter, “quite denuded of their feathers.” Pliny the Elder, writing many centuries later, explained birds’ winter disappearance in similar terms. Some species, he says in the Natural History “lose their feathers and conceal themselves” during the winter. Pliny declared it “a well-ascertained fact” that the turtle dove does just that.

By today’s standards, the strangest theory that Aristotle entertained as an explanation for birds’ winter vanishings was that some birds transmute into different forms each season. “The cuckoo is said by some to be a hawk transformed,” he reported, “because at the time of the cuckoo’s coming, the hawk, which it resembles, is never seen.” Aristotle expressed skepticism about this particular claim of transmutation, but he did believe in transmutation. For example, he thought that the robin and the redstart were actually the same bird: one was the bird’s winter and the other was its summer form.

During the Enlightenment, the period credited with the invention of modern science, naturalists scarcely understood bird migration any better than in Aristotle’s time. Transmutation theory seems to have died out, but hibernation theory persisted. Linnaeus, the father of biological taxonomy, believed that swallows spend their winters buried in swamps or frozen lakes. (One of his correspondents challenged him to demonstrate what anatomical feature could possibly allow swallows to do this.) Cuvier, the famous early nineteenth-century zoologist and paleontologist, also accepted hibernation theory. Even Gilbert White, the celebrated English naturalist and bird-watcher, was puzzled by the hibernation-migration debate. He wrote to a friend that, while he saw ample reason to believe that many birds migrate long distances, he also thought it likely that “many of the swallow kind do not leave us in the winter, but lay themselves up like insects and bats in a torpid state, and slumber away the more uncomfortable months till the return of the sun and fine weather awakens them.”

The seventeenth-century Englishman Charles Morton had a more fantastic theory than hibernation. He wrote a pamphlet hypothesizing that birds spent their winters on the moon. The theory seems ridiculous now, but Morton thought that the theory that birds hibernated in river bottoms was even more ridiculous than a theory that they hibernated on the moon. River bottoms, he pointed out, were cold and airless. Besides, he had seen birds departing in the sky each fall and returning from the sky each spring. “Now, whither should these creatures go, unless it were to the moon?” he asked. We remember Morton’s theory today as a bit of early modern bizarrerie, but it’s important to recognize that from his perspective, he was being scientific: identifying an open question, taking into account observations and known facts, and arriving at a theory that seemed, to him at least, logical and parsimonious.

It’s hard to determine when exactly the hibernation theory fell out of favor, but by the 1880s, Oscar Wilde could assume that most readers understood that swallows migrated every year. His fairy tale “The Happy Prince” narrates the unlikely friendship between a statue (the Happy Prince) and a Swallow (Wilde’s capitalization), whose “friends had gone away to Egypt six weeks before” to spend their winter there. The Swallow delays his migration, first because he has fallen in love with a Reed, and then to help the Happy Prince spread his wealth among the people of the city. One wouldn’t expect accurate ethological knowledge in a fairy tale, but in Wilde’s story the Swallow’s experiences in distant lands are a key part of the narrative. They make the Swallow’s choice to forgo migration and stay with the Happy Prince ethically meaningful.

*** The Invention of the Bird Band ***

Even as naturalists were arguing about hibernation and migration theories, a new technology was in the works that would one day lead to answers. The bird band was a lightweight metal ring that could be attached to birds’ legs to identify them without weighing them down too much. The earliest-recorded case of a banded bird seems to be from the late sixteenth century. A peregrine falcon belonging to the king of France, the story goes, got lost and turned up a day later in Malta, well over a thousand miles away. The bird was recognized by the ring on its leg. In this context, the band signified ownership—I belong to the king—a claim that was necessary only because the bird’s extraordinary powers of flight outstripped its “owner’s” territorial reach.

Bird rings came into use as a systematic way of studying migration in the late nineteenth century. In Europe, the Danish teacher Hans Mortensen started banding birds in the 1890s, putting his name and address on the rings so that people who found his tagged birds would report back to him. In North America, Paul Bartsch and Jack Miner created banding programs for herons, ducks, and geese. European ornithologists undertook similar projects, and the first atlas of bird migration was published in 1931.

People also began to recognize, in the nineteenth and early twentieth centuries, that many bird species were becoming endangered. They knew that human activities like sport hunting and the feather trade were to blame. Accordingly, new laws to protect these endangered species were passed. In Britain, the 1869 Sea Birds Preservation Act was the first bill of this kind. In North America, the 1916 Migratory Bird Treaty between the US and Canada (then still part of Great Britain) recognized the need for international agreements to protect migratory birds. Both countries established banding offices, which today work together as the North American Bird Banding Program.

By the 1940s, bird banders were at work across the world, using a card cataloguing system to keep track of band sightings. These systems held millions of hand-written, snail-mailed records. Today, bird banding remains one of the most popular forms of citizen science. The US Geological Survey’s Bird Banding Laboratory invites people to report banded birds they have found, maintaining a database that includes more than 64 million records. Similar programs exist in Australia, Africa, and Europe. Europe’s bird ringing organization EURING describes its data collection as an explicitly internationalist project: “Birds freely cross political boundaries, so international cooperation is essential if they are to be studied.” This statement reveals an important facet of post-1900 bird migration studies: their global, border-crossing ethos.

*** Cosmopolitan Birds ***

The internationalism of bird migration studies took on strong political overtones during World War II. Documentary filmmaker Irving Jacoby used migratory birds to promote “Pan-Americanism”—international cooperation between the countries of the Americas—in his 1942 High Over the Borders. The film, which was sponsored by the Office of Inter-American Affairs, the New York Zoological Society, and the National Film Board of Canada, followed the travels of barn swallows, Canada geese, and hummingbirds in an effort to show the world that the Americas were united. High Over the Borders begins with a story of barn swallows, whose migratory route connects the distant homes of “Richie,” a boy in North America, and “Ricardo,” his South American counterpart. Each boy regards the barn swallows as “his,” but in reality they share them. As the narrator earnestly declares, “The wild birds belong to all of us.”

Jacoby’s film is explicitly didactic, making bird migration an allegory for cosmopolitanism. As the narrator rhapsodizes, “A thousand miles are nothing, borders do not exist, for the birds have in their wings a passport to the world.” The 2001 documentary Winged Migration, directed by French filmmaker Jacques Perrin, makes the same point a bit more subtly. This film, which takes a minimalist approach to narration, is notable for its innovative uses of camera and aviation technologies to capture close-up views of birds in flight. The effect of the filmmakers’ elaborately rigged filming devices, as one reviewer put it, is to “[make] us feel that we are gliding along with” the birds.

The film scholar Jennifer Fay points out that the original French title for Perrin’s film—Le Peuple migrateur—literally translates to “The Migrating People,” and its German title translates to Nomads of the Air. These titles evoke a more direct parallel with refugees than the English-language one. Fay also observes that Winged Migration displays a bird’s-eye view of, among other recognizable edifices, the Great Wall of China, which from this perspective appears “an instinctive landmark rather than a monument to containment.” The film offers viewers a glimpse of what it would be like to move freely, without the walls and border checkpoints that constrain the human migrants below.

*** Year of the Bird ***

2018 has been designated the Year of the Bird by the Audubon Society, National Geographic, BirdLife International, and the Cornell Lab of Ornithology, because it is the 100thanniversary of the Migratory Bird Treaty Act. One of the earliest pieces of environmental legislation in the US, the MBTA “makes it illegal for anyone to take, possess, import, export, transport, sell, purchase, barter, or offer for sale, purchase, or barter, any migratory bird” except under permit. The law implemented the 1916 treaty between the US and Canada, which recognized that the two countries shared many bird species and thus shared responsibility for protecting them.

However, the Trump administration marked the centenary of the MBTA by rolling back its protections. In late December of last year, the Department of the Interior issued a new, looser interpretation of the law, which would stop holding energy companies liable for bird deaths due to their operations. The defanging of the MBTA is a setback for environmentalists; the fear is that energy companies will no longer have any incentive to take measures that would reduce harm to birds. But in the historical context of migration studies, it also seems like a renunciation of international cooperation. Migratory birds challenge nationalist and isolationist ideologies like Trump’s because they reveal the artificiality of national borders. No single nation “owns” birds, and no nation can protect them without international teamwork. Like refugees, birds demand an ethical and political framework that looks beyond the nation.

It’s a frustrating time for both environmentalists and migrant rights’ advocates. But it’s not all hopeless. As High Over the Borders and Winged Migration show, birds can inspire a vision of a future different from the present. Migratory birds can symbolize the hope for a world of fewer walls, more cooperation, and freer movement. As the poet Emily Dickinson once wrote: “Hope is the thing with feathers.”

Caroline Hovanec teaches English at the University of Tampa. She is the author of Animal Subjects: Literature, Zoology, and British Modernism. Her favorite migratory bird is the ruby-throated hummingbird.

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