A Common Nighthawk, a dark brown bird with long wings with white patches and a small, flat head, soars through a dusky sky. — Common Nighthawk. Westchester, IL, August 28, 2022. Photo by Matt Zuro.

words by David Hoyt

Birds that Swallow the Wind

I assume for at least a few dozen birds, 2023 fall migration began on the balmy evening of September 6, a Wednesday, at 6:30 p.m. It was the exact moment when, after parking the car, I opened the door, got out, and looked up.

Two dozen Common Nighthawks swirled in a gyre above the backyard. In the dimming light, a few spun off on centrifugal arcs, while a few others seamlessly returned to the core of the spinning flock, as if pulled in by gravity. Perhaps the insect hunting was good above this patch, and that is what brought them here. A few of us on the block had certainly worked to make it so, thickening our backyards and fence lines with plants that were food for legions of crawling and flying bugs.

Or perhaps the birds were indifferent to changes in the land beneath, and we, the most recent occupants, take too much credit for their presence. Perhaps they formed their gyre that Wednesday night, not far from the Des Plaines River, as they had done for millennia, long before the land had been arrogated from the prairie and its peoples. A display of what scientists call “site fidelity.”

This was the summer when I paid attention to nighthawks. In no small part, this was because of an enthusiasm sparked by and shared with the recently launched nighthawk survey orchestrated by Chicago Ornithological Society. All summer I listened for them. Or, I should say, I listened for one of them, the one that flew most every night at around 8 or 8:30. Walking the dog down to the park, I almost always heard the meep, meep that sounded like a loud cicada high above my head. Sometimes there were two of them, but I never saw more than two at once. I was impressed by the consistency of their routine. They seemed local. Like me, they had their patch and their habits. We were neighbors.

In late August, they began to fly lower, and with more bravado. Maybe the bugs were flying lower, too, and this is why the nighthawks dropped in altitude. They curved up and over the rooftops as if surfing invisible waves, swooping down into the canyons formed by driveways running between houses. No longer were they high above and hard to spot. On several occasions, a nighthawk shot out of our driveway and into the pseudo-savanna of the front yard, an opening between the houses and the row of parkways trees, half a dozen Green Ash and a towering Elm. It was exactly the same flight path as that of the neighborhood bats.

Bats and moths exist in an evolutionary state of war. By flying at night, moths—by far and away the greater number of the order Lepidoptera, which includes butterflies—evade predation by birds. But nocturnal flight exposes them to some of the most sophisticated of aerial predators, incredibly agile flying mammals deploying a form of biological radar. To counter this, many moths have evolved opulent, bearded wings and antennae, which diurnal butterflies lack. This lends many moths an appearance of furry, almost mammalian cuteness, like a toy animal. It also helps foil bat echolocation.

Nighthawks, in contrast to bats, are decidedly low-tech in their hunting adaptation. I think of them as flying whales. Like whales, they move large distances through their supporting medium and use their gaping maw to filter small organisms into their gut. It is a volume proposition, the opposite of the bat’s (or the diurnal bird’s) targeted hunting of individual insects. It also makes them ridiculous-looking and non-bird like, at least when feeding. I can’t be sure of it, because none of my views of nighthawks are anything but blurred, gray-scale impressions, but I think I saw one flying low with mouth agape over the backyard. I’m not sure how such a freakish image would have lodged in my brain if I hadn’t really seen it.

Like fellow members of the family Caprimuldigae, which includes nocturnal feeders such as European Nightjar and the Eastern Whip-poor-will, the nighthawk eats moths. Not nearly as many, apparently, as our woodland whip-poor-will, who primarily eats moths, but still a significant number. (Beetles, flying ants, and mosquitoes comprise the larger part of a nighthawk’s meals.) As anyone old enough to remember the late twentieth century “moth snowstorms” surrounding nighttime street lamps, porch lights, or car headlights may intuitively sense, the palpable decline in moth numbers, as with most insects, almost certainly makes things difficult for aerial foragers such as nighthawks, and even more so for whip-poor-wills.

A Common Nighthawk, a dark brown bird rests on a bare tree limb. — Common Nighthawk. Whistler Woods, May 6, 1989. Photo by Walter Marcisz.

Once you develop an interest in Caprimuldigae, it is hard not to develop an interest in the nocturnal Lepidopterae. They are both masters of camouflage. If it is your way to sleep during broad daylight, then you must make yourself very difficult to spot. How effective they are becomes clear when you reflect upon the fact that, much less conspicuous than butterflies, moths vastly outnumber their diurnal brethren. The nighthawk at rest—and I know this only from pictures I have seen, and not from firsthand observation—oddly resembles a moth, especially a moth of the Geometridae family, the typical little gray things that beat against a summer window. So confident is the nighthawk in their power of dissimulation that they nest on the ground and roost on a horizontal branch, leaving cavities or high nests to more timid birds. Both nighthawks and moths have the ability to magically blend in with the bark of a tree or the litter of the forest floor. Not all moths are like this, of course (Think only of the legendary Io or Polyphemous moths.), but many of the species fed upon by nighthawks are. Adopting common defenses by day, they become enemies by night.

I once heard it said, by someone who has been birding far longer than I have, that the birds you can see in your backyard are the birds you can see anywhere. After some time spent birding in my backyard, I would offer the following qualification: If you spend enough time sitting still, you will see the universe.

Before the great gathering of the evening of September 6, I noticed an uptick in evening nighthawk numbers. For a few weeks they flew in threes or fours. I put a lawn chair out back at dusk and made myself dizzy trying to anticipate from which horizon one would appear. I strained my eyesight attempting in vain to photograph them. I had much better luck capturing the lustrous, brightly painted fuselage of passenger jets taking off in the warm light of the setting sun. I now know that this period was the foregathering, the build-up to the Great Gyre.

Nighthawks gather in a few meeting places before heading south along the Mississippi Flyway. Where did these two dozen nighthawks come from? How did they know to meet, and where? Did they know each other? Had they flown together before? After the evening of September 6, they were gone from suburban Chicago, embarked upon one of the longest flights of any North American migratory bird. Bound for the lee side of the Andes, in far South America.

There is a single page in my ancient, hand-me-down Peterson’s Guide to Birds East of the Rockies (1980) that is a veritable portal into a world fantasy, myth, and bawdiness: the page devoted to alien-looking Goatsuckers. Common bird names are generally not the most interesting, at least not in English, but here we have a ringing exception. (For the delight to be had in common names of other fauna, please consult any number of moth names, such as Tarache delecta—Delightful Bird Dropping Moth.) What on earth is a goatsucker? It has all the flavor of something from a Renaissance bestiary.

A Renaissance bestiary, in fact, is exactly where the English word goatsucker first came to print.

A 16th century illustration in a book features large birds with small mammals and snakes in their mouths, as well as a goat being suckled by a small bird. — “Nocturnal Birds and Their Food.” A bird, presumably a nightjar, can be seen in the lower left-hand corner of the image, sucking the teat of a goat.

Merriam-Webster will tell you that the first use of the name occurred in the early seventeenth century, or 1611, to be precise—the age of Shakespeare, Sir Walter Raleigh, and the King James Bible. A dubious website calling itself “The Content Authority” apparently found it hard not to claim that Shakespeare himself put the word into the mouth of his character Puck, in A Midsummer Night’s Dream: “foul and hateful birds” that “suck the blood of goats.”

A search of the entirety of Shakespeare’s works in MIT’s online compendium reveals that The Content Authority is on this point no authority at all, as there is nowhere in Shakespeare mention of a goatsucker. But, as is often the case, truth is stranger than fiction. It turns out that the first printed use of the English word or its approximation may be in the bestiary of a forgotten English cleric, Edward Topsell, whose History of Four-footed Beasts, first compiled in 1607, was published in 1658: “There are certain birds (called Capri-mulgi) because of their sucking of the Goats, and when these or any of them have sucked the goat, she presently fall blind.”

Topsell’s 1607 bestiary was published by William Jaggard, whose publishing house in 1623 brought out the First Folio of William Shakespeare. So, in the end, there is a link between Goatsuckers and Shakespeare.

Topsell died before he could complete his last great zoological work, The Fowles of Heaven (1613-1614), an unfinished alphabetical encyclopedia of birds going no further than the letter C. A list of 43 birds to be included in Topsell’s project included a never-written entry for “Goate sucker.”

Of all the many names given to this bird and its close kin over the centuries and around the world, my favorite is the one by which it is known in France: l’Engouelevent. “The bird who swallows the wind.”

In 1884, a young teacher named Wells Woodbridge Cooke published a list of bird names in the first volume of The Auk, what would become the official journal of the American Ornithological Union. He had learned these names from residents of the Indian Boarding School at the White Earth Indian Reservation, east of Itasca, Minnesota. The Indian school at White Earth, like others across Minnesota and across the United States, was intended to eradicate the cultural identity of indigenous peoples and assimilate them to American norms. It was Minnesota’s first such school (founded in 1871). The teaching job was Cooke’s first out of college, in 1880.

In 1881, while recording bird migration data at White Earth, he began taking down names in his own transcription of Ojibwe, using French phonetics. Entry #48 is: “Nighthawk. Chordiles Popetue. Besh-qué, imitation of the peculiar noise it makes as it swoops down when flying.”

This entry is preceded by that for the whip-poor-will, or “Gwen-go-wi-a’ imitation of cry.”

Cooke later went on to be a migration expert in the employ of the US Biological Survey, an active Audubon member, and a strong advocate of the Federal Migratory Bird Treaty.

The mid-century ornithologist Alfred Otto Gross, noting these distinct Ojibwe names for two distinct species, wrote, “That the Chippewa Indians differentiated these two species is all the more remarkable when we recall that this distinction was confused by Catesby and the American ornithologists of the next 50 years who followed him.”

Put differently, the Ojibwe knew all along what it took a century or more of shooting and collecting by Euro-American ornithologists to figure out. Some knowledge is just as well arrived at through slow acquaintance than in the rush to accumulate and classify.

A Common Nighthawk, a dark brown bird with white patches on the wings, looks small as it soars in high up in a blue sky. — Common Nighthawk. Momence Wetlands, May 26, 2017. Photo by Geoff Williamson.

The evolutionary past of nighthawks and their relations is characterized by both mystery and controversy, quite apart from the ancient European myths tying them to the teats of goats. In the pre-genomic era of avian taxonomy, when anatomy was the primary grounds for assembling organisms into relationships of kinship and descent, nighthawks were grouped together with a cosmopolitan number of similar, large-mouthed, nocturnal birds: potoos from South and Central America, which roost in vertical position, rather than on the horizontal, as do Nighthawks; frogmouths, Australasian species with even more freakishly, frog-like gapes, flat heads, and facial (“rictal” and “nasal”) bristles; owlet-nightjars of New Guinea, tiny birds that appear, as their name suggests, to be miniature owls, but are probably a startling case of convergent evolution, with only distant relation to owls (Order Strigiforme); and the South American Oilbird, the world’s only cave-dwelling, nocturnal, fuctivorous bird (Steatornithiforme). Even the hummingbirds, by way of their descent from swifts, have at one time been included in this grouping.

Recent genomic research has led to most of this menagerie, including hummingbirds, being released from confinement within the Order Caprimulgiformes, which is then reserved for nightjars alone, or the Common Nighthawk and its close Eurasian allies.

The last monographic study of the order, Holyoak’s Nightjars and Their Allies (2001), presented the older, cosmopolitan cast of characters, including Oilbirds, potoos, frogmouths, and owlet-nightjars, together with the familiar nighthawks and nightjars. It was published two years before the completion of the human genome project, and four years before rapid and high-volume gene sequencing technology became commercially available in 2005. By 2010, a paper in the journal Molecular Physics and Evolution concluded, based on a genetic phylogeny built on DNA “from more than 60% of caprimulgid species and 14 of 16 currently recognized genera” that the taxonomic family Caprimuldigae is a grab bag of birds that more or less resemble the Common Nighthawk, but which probably each evolved independently from different ancestors under similar pressures of natural selection. What we see as a nighthawk may, in fact, be but one version of a common and very successful design to which aerial feeding birds of different ancestries have evolved time and again.

It can take me years to identify some birds. They form a set of cold cases in my memory, unsolved mysteries, like vague diseases described in an ancient text, or strange flying objects seen by Navy pilots. Only with time and a certain base of observational experience has it become clear in retrospect what probably I saw. Such was the case with my first nighthawks, seen five years ago.

The two birds flew low and over my head, out of my driveway-canyon at dusk, then followed the edge of the open yards along the parkway and off down the block. The same route the bats follow. They made a call, which I wasn’t quite sure of. I noted the long wings curved to a point, and the aerial maneuverability. I had no idea what they were, although I was enthralled. Gulls? Merlins? Hawks? Falcons?

Five years later, it is about half an hour before dawn in June, and I am trudging through a field in some nearby woods, about to survey for breeding birds. There is a lot going on: a pair of coyotes crosses the road, one of which carries some prey, perhaps a rabbit. Other mammals rustle in the brush as I pass. Deer watch me carefully. A bluebird approaches me, perches near my head, and gives a most unearthly, haunted song. Before I can fully appreciate the blueness of this bluebird’s song, I hear the meep that I have grown to know so well over the last few summers. It is my neighborhood nighthawk, feeding at dawn. But this bird wasn’t high above, nor alone. Two of them swoop down from the edge of the forest canopy, the way they had five years ago, as if following or chasing one another, a yard or two over my head. In passing, I hear it: meep. Mystery solved: diagnostic certainty achieved. These are nighthawks, coming in from their morning hunt. And they were probably nighthawks that I saw five years ago.

Birding Through the Year: Fall 2023