Birding Through the Year: May 2023
words by David Hoyt
A Little Night Music
On a recent night in May, I lay awake in bed. What to do? It is 1:45 in the morning, and the worries I thought I had put in order at bedtime now erupt from their crowded roosts like a torrent of Chimney Swifts at dusk. I could read a book. I could make myself a glass of hot chocolate, or maybe finish off the bottle of red wine on the table downstairs. Maybe I could walk the dog.
Had it been mid-January, I might have done one or all of these things in the attempt to coax my mind back to dormancy, to entice my flocks of insistent worries back to their hideaways. But it was May. I sensed how quiet things were outside. Minutes went by between the sounds of passing cars. The sky was recovering from its daily burden of air traffic. It was obvious what I needed to do. Tranquility beckoned me outward, not inward. I needed to get outside and listen for birds.
If you’re like me, you can often pinpoint the origin of some obsession or quixotic pursuit to the day and minute when something incredible was revealed to you. As I took a seat on the front steps at about two o’clock in the morning, a glass of wine in one hand and a smartphone loaded with Merlin’s Sound ID app in another, I thought back to the day when I first learned of Orin Libby. It was during the first, cold spring of the pandemic. The world had shut down. Curled up on the sofa and waiting for the rain to end, I came across Libby’s curious story while reading Kenn Kaufman’s newly-published book on spring migration. [1] Young Doctor Libby, though a doctor of American history and not of ornithology, has nonetheless gone down in the annals of migration research as the first person to make a methodical count of birds passing overhead at night. He did this both by attentively listening to calls, and then, with the cooperation of a faculty astronomer, by observing through a six-inch telescope the silhouettes of birds as they passed across the disk of a full moon.
In the eyes of his boss, Frederick Jackson Turner, then the illustrious dean of American history and chair of the department at the University of Wisconsin, Madison, this most literal case of moonlighting was a contributing cause for the denial of an assistant professorship to Libby in 1902. Libby’s offense was that he was publishing scholarly articles in ornithology, though in doing so he made history. One of his articles relates the experience of that night in mid-September of 1896, when he undertook to count birds migrating overhead.
Nothing but an actual experience of a similar kind can at all adequately convey the impression produced by such observations. The air seemed at times fairly alive with invisible birds as the calls rang out, now sharply and near at hand, and now faintly and far away…. All varieties of bird calls came sounding out of the darkness that evening. The harsh squawk of a water bird would be followed by the musical ‘chink’ of the Bobolink. Almost human many of them seemed, too, and it was not difficult to imagine that they expressed a whole range of emotions from anxiety and fear up to good-fellowship and joy… The great space of air above swarmed with life. Singly or in groups, large and small, or more seldom in a great throng the hurrying myriads pressed southward. It was a marvel and a mystery enacted under the cover of night, and of which only fugitive tidings reached the listeners below. [2]
If this sounds almost mythical, it probably is, the way many of the encounters with large-scale nature now seem to us over a hundred years later. Yet, even as Libby described this majestic natural event, it came at the end of a closing era of wild abundance. Libby’s boss, Frederick Jackson Turner, made his mark declaiming the end of a different, though closely related, era. Only three years before this ornithological experiment, in 1893, Turner gained fame by reiterating an 1890 determination of the Census Bureau that a proper line frontier settlement no longer existed, and declaring that this marked the end of a formative era in American history.
Read with an environmental sensibility, the thesis captured something more than a story of national character formation. It implicitly announced the doom awaiting a significant proportion of North America’s bird populations among other organisms. The closing of the frontier was a message to the wild things of America that the great open spaces which they had relied upon for their reproduction and flourishing were now subject to fences, plows, and pavement as much as from commercial hunting. By the time Jackson announced his thesis, in the Art Institute of Chicago during the Chicago’ Columbian Exposition of 1893, the enormous population of passenger pigeons, Ectopistes migratorius, the subject of so many awe-struck nineteenth century accounts, was crashing. Estimated in the early 1870s to have a breeding population of 136 million in its home base of central Wisconsin, by the 1890s the passenger pigeon was found in flocks of no more than a dozen individuals. The last bird taken in the wild was shot seven years after Turner’s speech, in 1900, in Ohio. [3] When Potawatomi leader Simon Pokagon spoke at the same Columbian Exposition of the rapacious exploitation of nature he had witnessed during the second half of the nineteenth century, as the frontier raced westward, he visualized his condemnation of those responsible with a searing image of injured birds rendered unable to fly. [4]
These were Libby’s times: great extinctions were happening, but it was still possible in places to climb a hill and listen to inconceivable abundance. I, like the rest of us, am more accustomed to inhabiting a depauperate age, and so necessarily take joy in the beauty that remains. And so I sat in the relative quiet of West Suburban Cook County one night in May, on a hill of two concrete steps, enjoying the aural equivalent of a New Moon, and began to listen, over a century after Orin Liddy sat on his hilltop and began to count.
There are noises, without question. Not dogs or children or chipmunks. Gentle chirps from all around. But who are their authors, and are they aloft, or landed? “Most bird lovers know distinctly the call of the migrating birds can be heard during the nights,” Libby related, speaking of mid-September but surely to some degree of the spring months as well. I keep the light from my smart phone shielded under a hand towel, and activate Merlin’s Sound ID function. It is two o’clock in the morning.
In short order, Merlin returns IDs for a Veery, a Swainson’s, and Gray-Cheeked Thrush, a trio of woodland flautists. The Swainson’s is convincing, as I had heard them in my yard for a week or so up to then, and indeed again just that afternoon.
Twenty minutes or so go by, and I begin a fresh recording. No more than a second or two elapse before a Scarlet Tanager is identified. I am astounded. This most conspicuous of birds, in no way camouflaged for the forests of temperate latitudes, nor particularly adapted to the darkness, this bird that steals through the forest canopy like the red tail-light of some receding ghost train, this is the animal now flying overhead?
The sonogram is distinct, a U-shaped whistle, descending and then rising quickly in pitch. It shows up twice on the graph and conforms to the flight call of Piranga Olivacea, the Scarlet Tanager. Five days later, I come across a pair red and frolicking in the tall timber several blocks away. It could have been one of them.
Libby spent the night on his hill west of Madison and counted 3,800 calls in total, “an average of twelve per minute,” noting that the peak occurred between two and three o’clock in the morning, the very hour I of my doorstep auditory. In that hour, he heard 936 calls with his unaided ear. I couldn’t imagine such traffic, even were my ears powerful enough to hear it. The sensation of such a rush of life in darkness much have been unforgettable. But Libby had no way, for the most part, of knowing what was flying overhead. I have in my hands the fruit of over a century of recording and sound analysis technology. Libby could count chips and whistles. I can—or even not hear—vocalizations and have some degree of confidence as to what species just passed by. Such are the tradeoffs of modern civilization.
In less time than it has taken you to read this last few paragraphs, even more interesting results came back: two shorebirds, a Solitary and Spotted Sandpiper. This was as exciting to me as first spotting a colorful warbler in a spring hedge. Could these strange birds that seemed decidedly earth-bound, made for waddling and probing in the mud with their straw-like bills, really be cruising above, probing bills and all? The IDs were not entirely unconvincing: I spot a Solidary Sandpiper in my patch once or twice every spring if it rains enough or the river floods. They have to get here somehow, and here it was, tracking in the airspace between the Jewel-Osco down the street and Johnny’s Italian Beef a few blocks north.
The call of the Solitary Sandpiper is relatively high in pitch, enough to be difficult for me to perceive. But the graph is there—three rising whistles, symmetrical, indicating consistent change in pitch and constant duration. The pattern occurs several times, and matches sample graphs of the same bird. Pilots steer enormous aircraft through the night between continents on information of equivalent abstraction, entirely derived from instruments and divorced from human perception. Why should I dispute the product of an aural prosthetic such as Sound ID, a sensory assistant not too different from a pair of binoculars?
In the community of local breeding bird monitors, there is a healthy skepticism regarding Merlin’s sound identification feature. For summer bird monitors, birding by ear is the name of the game. An ear-witness trumps everything else. And it is true that sometimes, Merlin is wrong. It once told me that a friend with a pronounced Adam’s apple and a guttural way of saying “uh huh” was a Least Bittern. But very often, it hears birds before I hear them, and just as often hears birds before they fly in front of me. The apprehension of some is that, when the recordings are taken from the field and listened to at home, they are often faint or inaudible and so worthless as identification. This is often true.
But it overlooks the fact that Sound ID generates an inscription—a sono-graph—that can be very precise even when it accompanies a recording that is less meaningful to human hearing. And these inscriptions are often unique, or at least quite distinctive. There is nothing else in nature, for example, which will leave a sonographic inscription like the song of the Eastern Wood-Pewee. It is indisputable what species you have detected when you see that elegant, cursive signature line roll out along the time axis. (Although a mockingbird or Blue Jay may mimic the pewee, the curve is the pewee’s sole invention). To know what you may or may not have heard, therefore, you need to trust your eyes.
In the time it has taken to read a few more of these paragraphs, still more thrushes flew by, and a Rose-Breasted Grosbeak—not improbably, again, considering that one had been singing in the back yard for the last week. But the Savannah Sparrow brought me up against the limit of my trust in technology. The Savannah Sparrow is among those birds I’ve seen only once, maybe twice. I’d be hard pressed to tell you what it looks or sounds like without referring to a field guide. It vocalizes at a high pitch in song (Merlin, unfortunately, does not scale its sonograms in kilohertz.) and very high when calling. On my fifteen-minute sonogram, only one inscription is tagged as belonging to a Savannah Sparrow. A single, faint, elevated, chirp. Merlin is confident. I am not.
I want to believe that this tiny bird that is a rarity for me has charted a course directly above our neighborhood, and that I was a witness to its brave journey north. But I don’t have the confidence, I have no circumstantial support. I hadn’t seen one around, there were not repeated calls to establish a pattern, and the inscription itself was weak. It was like an interstellar object, Oumuamua, passing obliquely across Earth’s orbit, flashing and spinning and mysterious.
Merlin may have been right. It is very smart. But, to me, there just wasn’t enough there. This bird, I let fly on into the night.
[1] Kenn Kaufman, A Season on the Wind: Inside the World of Spring Migration, (Boston: Houghton Mifflin Harcourt, 2019).
[2] O. G. Libby, “The Nocturnal Flight of Migrating Birds,” Auk Vol. XVI, (April 1899): 141.
[3] Barry Yeoman, “Why the Passenger Pigeon Went Extinct,” Audubon. From the Magazine (May-June 2014).
[4] Simon Pokegon, The Red Man’s Greeting, 1492-1892. (Hartford, Michigan: C. H. Engle, 1893), p. 14. “The drum will be sounded, and that innumerable multitude will appear as some vast sea of wounded birds struggling to rise.”