by David Greer
I used to visit our airport on Vancouver Island not to catch a flight but to hear the skylarks. I stood in the parking lot and looked up. The stares from passengers arriving and departing seemed a small price to pay for the reward of listening to the endless birdsong spilling from the sky above the terminal.
The Eurasian skylarks were all but invisible, hovering two or three hundred feet above me, but I was familiar with their routine. Male skylarks begin their song flight with a rapid ascendance to hovering altitude, where they deliver their unbroken melodious stream, lasting up to 20 minutes. The longer and more complicated the song, the greater the likelihood of impressing a potential mate. The grassy fields around the runways provided ideal nesting sites for one of the last remaining skylark populations in North America. Fortunately, whenever I visited, the airport sky seemed always to overflow with skylark song, albeit to an intermittent accompaniment of airplane engines.
Eurasian skylarks were introduced to several American states in the nineteenth century by European immigrants nostalgic for the birds of home. A further introduction to Vancouver Island in 1903 was sufficiently successful that the local skylark population had grown to more than a thousand by the early 1960s.
Although only the male skylarks engage in the aerial opera, the long-standing belief that courtship songs are primarily the province of male birds has been well and truly shattered. That theory likely arose from the fact that early naturalists primarily made their observations in temperate zones where male birds play a larger role in birdsong. But the majority of songbird species are tropical (unsurprising, given that birds evolved in the general vicinity of Australia), and a 2014 study of almost all songbird families demonstrated that female song not only occurs in more than two-thirds of those species but also may be just as long and complex as male song.
Many early ornithologists are remembered in the names of bird species such as Cooper’s hawk, Townsend’s warbler, Audubon’s oriole, Wilson’s storm petrel. But these naturalists now find themselves on the wrong side of history. In 2023 the American Ornithological Society announced plans to drop the names of people and replace them with descriptive language. “There is power in a name,” said the statement, “and some English bird names have associations with the past that continue to be exclusionary and harmful today”. Be that as it may, it’s a necessarily controversial rationale among members of the scientific community, given that all plants and animals have internationally recognized genus and species names and that common names vary widely by region, in addition to which many species names are Latinized versions of a usually male first describer of the species, a circumstance unlikely to change.
But I digress. The seemingly endless symphony of skylark song inspired European works of poetry and music as varied as Shelley’s “Ode to a Skylark” (“Better than all measures / Of delightful sound”), John McRae’s “In Flanders Fields” (“and in the sky / The larks, still bravely singing, fly / Scarce heard amid the guns below”), and Ralph Vaughan Williams’s “The Lark Ascending”, in which a violin brilliantly evokes the rising and tumbling notes of the little brown bird, so entrancing listeners that it has repeatedly been voted Britain’s favorite piece of classical music.
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The Thrush and the Syrinx
While a violin may do justice to the beauty of skylark music, a flute seems a better fit for the ethereal notes of the hermit thrush or the upward-spiraling song of the Swainson’s thrush. Writing teachers talk about the power of the five senses to evoke strong memories in readers, and for me one of the most powerful avenues to the past is birdsong.
The Swainson’s thrush in particular takes me back to a specific time and place, coasting down a highway through a pass in the Canadian Rockies, the breeze rushing through my hair while Swainson’s thrush melodies echo from the forest one after another as I pass from one bird’s territory to the next. In another memory, I stand entranced in a tall Carolinian forest in Ontario, the silence broken only by the sweet notes of a lone hermit thrush. I remember thinking of the forest as a leafy cathedral, dust motes drifting along slabs of sunlight breaking through the spring-green canopy while the exquisite solo continues, punctuated by brief silences between different phrases.
In retrospect, it seems more accurate to describe the performance as a duet rather than a solo, as it sounded for all the world like two voices singing in glorious harmony, though I was certain I had only seen a single hermit thrush. As I learned later, it wasn’t just in my imagination that one tiny bird was producing two different notes simultaneously. Birds produce sounds differently than reptiles, amphibians and mammals, whose larynx at the top of the throat protects the airway while also acting as a voicebox. Birds have a larynx too, but the organ they use to produce sound sits lower in the throat, where the windpipe forks into two tubes that connect to the lungs.
This organ is the syrinx, named after the Greek nymph who was transformed into panpipes. Unlike panpipes, the syrinx doesn’t have multiple pipes, but what it does have are membranes on either side that vibrate as exhaled air rushes past them, producing sound. By contracting and relaxing the muscles to manipulate the sound, a bird can change the pitch and amplitude of its song. This ability is particularly refined in songbirds, some of which can produce two vocal sounds simultaneously by controlling the two sides of their syrinx independently, thus producing, in the case of thrushes, an avian version of two-part harmony.
And that’s not all. Whereas the efficiency of a human larynx in producing sound is around 3 per cent, almost 100 per cent of the energy forced under pressure past the membrane of syrinx is translated into sound. As Colin Tudge puts it, “If Pavarotti had had a syrinx, no opera lover would have been safe. Covent Garden, La Scala, and the Metropolitan Opera House would surely have been shaken to their foundations” (Consider the Birds, p. 33). A promising candidate for the bird equivalent of Pavarotti might be the winter wren, which tips the scales at all of nine grams when fully mature, has a complex song and, taking into account the size difference, has up to ten times the vocal power of a rooster.
The complexity of many bird songs must be attributed at least in part to several million years of practice. The syrinx first evolved around the time bird groups became established, some 67 million years ago, shortly (in geological time) before a stray asteroid wiped out all of the other dinosaurs inhabiting the planet. One theory has it that the evolution of the syrinx came about as a response to the lengthening of the necks of some birds to facilitate underwater feeding. The longer the neck, the greater the resonance produced by the operation of the syrinx, the most obvious example today being the vocalizations produced by such long-necked birds as swans and geese, which rely on loud calls for communication during their long-distance migration.
Every spring I keep my ears tuned for the calls of birds so high up I have to strain to see their outlines–the snow geese and tundra swans and greater white-fronted geese that migrate above my part of the continent on their annual journey to nesting grounds hard by the Arctic Ocean. I may not even be able to see their tidy Vs or garbled widespread Ws, but the volume of their calls declares their presence. I’m aware that greater white-fronted geese are known as “laughing geese” because of their calls but given the height at which they cross my part of the country, calling to one another constantly and loudly, I’m at a loss to determine whether the calls are laughter or honks or the querulous bleats associated with other long-range flyers in the Anatidae family of waterfowl.
Incidentally, the ability of some songbirds to independently control the separate cavities of the syrinx also enables them to breathe while singing, which is why the skylark seems able to sing without cessation almost indefinitely. No pauses for sharp intakes of breath for these avian virtuosos.
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The Dawn Chorus
But back to thrushes for a moment. One of their clan is the ubiquitous American robin–ubiquitous in North America, that is, the European robin redbreast being of the flycatcher clan and therefore not even a kissing cousin. Most North Americans are familiar with the American robin, including those who in early spring might publicly love the creature while privately harboring the inclination to throttle it, syrinx and all, most especially in the predawn hours if their bedroom window happens to be open at this time of year when a male robin’s fancy turns to love.
Sunrise on the day I write these words was at 6:28 a.m. here in the Pacific Northwest. Promptly at 5:30, the courtship song of a robin came barging in my bedroom window. It was loud. The American robin may not have as refined a song as the hermit thrush, but it knows how to use its pipes. This particular robin took the lead in today’s dawn chorus. Why a robin rather than the chickadee or the junco or the mewing towhee scuffling in the dirt? Most likely because birds with larger eyes and greater ability to see in low light sing earlier than others, according to a study in the UK.
The dawn chorus is a big deal in birdland. This is when birds of all shapes and colors hold forth to woo a mate or stake out their territory or try out a new tune while it’s still a little too dark to see a worm or whatever appeals to one’s breakfast fancy. But what drives birds to sing before sunrise? Jennifer Ackerman suggests it may have something to do with improved acoustic transmission during those early hours. Or maybe because predators are less of a threat. Or maybe because low light makes foraging difficult. Or maybe because this is a convenient time for practicing daytime tunes. Or maybe they’re just celebrating the fact that they survived another night (The Bird Way, p. 29). In short, though we’ve learned a lot about the behavior of birds in recent years, they’re still pretty much a mystery.
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Songs, Calls, and Dialects
One thing we do know is that birds sing songs and, separately, issue calls. Since we’re talking about American robins, this bird in the hand is as good an example as any. At the crack of dawn, the robin is feeling good and chortles away, loudly and continuously. Its chortles contain a bunch of syllables and rise up and down, indicating that all is right with the world and that worms will soon be gotten by this early bird. Donald Kroodsma, who has paid closer attention to the details of bird songs than most, describes the robin’s song as “several low caroled phrases, cheerily, cheer-up, cheerio, followed when excited by a high, screeching hissely (or eek!), a brief pause, and then continuing” (Birdsong for the Curious Naturalist, p. 10).
A little later in the day, post-worm, robins continue to chortle, a little less vigorously, but if a cat or an eagle or a human enters the stage, the song abruptly ends and is replaced by an alarm call–for the robin, it’s a high-pitched cluck! cluck! cluck! Loosely speaking, the difference between a song and a call is that a song is a relatively long, often melodious series of notes usually related to courtship, while a call is a brief sound with a simple acoustic structure like a peep, cheep, or squawk.
The typical purpose of birdsong is to attract a mate or defend territory, and the more impressive the song, the more likely the singer is to achieve its purpose. That is why many songbirds constantly improvise new variations to their songs, and it’s also why they start to learn songs from adults of the same species at a very early age, even while in the shell, in some cases.
Some songs are so elaborate and so varied among individuals that others of the same species can identify an individual simply by the sound of the song. Regional differences abound as well, with different songbird populations developing different dialects, just as humans do. And, as in humans, innovations in the structure and syntax of songs are common and can spread quickly from population to population. The signature libretto of the white-throated sparrow was O sweet Canada Canada Canada until an enterprising individual was inspired to change the refrain to O sweet Cana Cana Cana. To say that got noticed among the avian tribe is an understatement. In two brief decades the new dialect spread all the way from British Columbia to Ontario. By contrast, some other species such as the black-capped chickadee have no regional or local dialects and sing the same tune no matter where they are in the continent. That includes the olive-sided flycatcher, which calls “Quick! Three beers!” no matter what brand is locally available.
“The littlest birds sing the prettiest songs,” sang the Be Good Tanyas, and the skylark and the hermit thrush seem proof enough of that. It would logically make sense as well that songbirds sing songs and other birds don’t, but it’s not as simple as that.
Songbirds are defined not by their inclination to sing but rather by their identity as oscine passerines, a subset of the order Passeriformes, perching birds with three toes pointing forward and one back. Oscine passerines, or songbirds, include roughly 5,000 species, about half the planetary total. While they do include the littlest birds with the prettiest songs, they also include the common raven which, while it may sound like a creative percussionist in its whimsical moments, is no skylark. Another Passeriforme suborder is the suboscine passerines, which include species that sing, less musically than most songbirds but certainly more melodiously than a raven.
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Late Night Singers: The Lonesome Whip-Poor Will
Not all bird species join the morning racket otherwise known as the dawn chorus. One of my favorite bird memories takes me back to an evening on the bank of the French River, close to its mouth on Lake Huron’s Georgian Bay, pleasantly exhausted after our long day’s paddle downriver. We’re lazily watching the campfire coals glowing in the deepening dusk beside the burbling water of a river that’s more like a long, narrow lake when into the still air floats the haunting call of a whip-poor-will, softly repeating every few seconds. I had never heard a whip-poor-will before and have never heard one since, but there’s no mistaking the identity of a bird calling its own name, just as other species such as the killdeer do. While the whip-poor-will is not a songbird by definition, its evening call functions as a song in performing a similar purpose–to announce its territory or court a mate–and arguably has a more pleasing sound than the song of a starling (a songbird), not to mention the crazy-making cacophony of a murmuration of starlings.
I’ll never hear a whip-poor-will call here on the Pacific coast, but its close cousin the common nighthawk (both are nightjars) makes nightly appearances overhead, relieving the summer sky of mosquitoes. While the nighthawk’s raucous peent may be less melodious than the call of the eastern whip-poor-will, that’s not its only sound. Typically, a series of peents is followed by an otherworldly vroom, a reliable source of confusion to those who hear it for the first time. That vroom is produced not by the bird’s beak but by the air rushing through its wingtips at the end of a sudden dive which, like most noises produced by male birds, is intended to signal its suitability as an ideal mate. The Anna’s hummingbird in my own backyard favors the same stunt, except that the sound it produces is an identical copy of an excruciatingly loud marmot’s alarm whistle. (The hummer’s song is nothing to write home about, unless you have a fondness for the sound of a thumb running down the teeth of a comb.)
The dives of the common nighthawk and the Anna’s hummingbird (I have never heard or heard of other birds performing a similar behavior) are simply one example of non-verbal communication practiced by birds who may lack a compelling song. Every spring I am accustomed to being awakened at irregular intervals at the crack of dawn, when the robin is distracted or otherwise unavailable, by an ear-deafening hammering on the metal flashing that secures my woodstove chimney to the roof. As alarming as this was the first time I heard it–has the magnitude nine earthquake finally come to pay a call?–I now recognize it as merely my old friend the northern flicker, who has somehow got it into his drilling-addled noggin that the dismantling of my chimney is surely the shortest route to a lady flicker’s heart.
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A Farewell to Skylarks
Soaring skylarks and landing jets do not make a happy mix. Meadows need to be mown and new landing strips paved as traffic increases. Initially the airport authority did its best to accommodate the skylarks. Then it tried relocating the skylarks to fields far removed from planes. That experiment did not end well.
Over the years, the skylark concert above the airport gradually softened from a joyous symphony to a muted sonata. And then came the time when I no longer heard skylarks from the airport parking lot. After that I relocated to access roads around the airport perimeter, with diminishing success until the sorry day I heard only the sighing breeze and engine noise.
Today, dedicated birders occasionally report hearing a skylark singing in the vicinity of the airport, but those reports are few and far between. Based on those reports, the current population of skylarks is estimated to include five males at most (males being the ones that are heard singing) and quite possibly fewer than that. That handful of birds is almost inevitably doomed to disappear in the near future, lacking sufficient numbers and the secure habitat needed to sustain even a small population.
When that day arrives, it will mark the final extirpation of skylarks from North America, Victoria international airport being their last remaining refuge. Skylarks may continue to sing over Flanders Fields, but they will have been forever banished from the skies of this continent.
At that point skylarks will join a legion of other disappearing species. In British Columbia, these include the northern spotted owl, in all likelihood extirpated from Canada following relentless logging of the old-growth forests where it nests–the one remaining spotted owl in the country, released to the wild from a breeding program, appears to have gone missing at least a year ago. Similarly, the burrowing owl has recently been extirpated from British Columbia, unable to withstand the conversion of its habitat to agricultural uses.
A 2019 analysis of population trends for 529 bird species, led by the Cornell Lab of Ornithology, concluded that wild bird populations throughout the United States and Canada have declined by almost 30 per cent since 1970. That’s a lot less birdsong. Shades of Silent Spring?
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Sources for this article include Jennifer Ackerman, The Genius of Birds (New York: Penguin, 2016) and The Bird Way (New York: Penguin, 2020), Donald Kroodsma, Birdsong for the Curious Naturalist (New York: Houghton Mifflin, 2020), and Colin Tudge, Consider the Birds: Who They Are and What They Do (London: Allen Lane, 2008). Thanks to Ann Nightingale of the Victoria Natural History Society and to Jared Hobbs of J. Hobbs Ecological Consulting Ltd. for updates on the status of skylark and owl populations, respectively. And thanks also to Myles Clarke for his generous permission to complement my writing with his outstanding photographs of singing birds.