The Nighthawk’s Trajectory

What the trajectory of Common Nighthawks tells us about the suburban landscape.

I’m an agnostic in all things but nighthawks, for with the bullbat I hold this belief: one cannot pursue the bird directly; rather, one can only seek a trajectory that may someday cross theirs. 

My faith in the bird was born amid their southward migration through Denver, Colorado, in September 2015. I’d gone looking for nighthawks in a place where and at a time when I thought it likely I might see one. Common Nighthawks are (mostly) crepuscular; they hunt for flying insects through dawn and dusk. Walking around central Denver’s Cheesman Park after sunset, eyes aimed upward, I found only brown bats. I sat a while, awaiting night, and watched these other things with wings. Then, I left.

In truth, I just readied to leave. I sat in my car and, though it was a Sunday and though it was evening, I compulsively checked my email. A (lengthy) message from my department chair at the University of Denver greeted me. Compulsively, I read it, though I believe one should neither mix time off with work nor birds with the same. Dusk gave way to night. The bats gave way to a still park.

At the end of the email, nighthawks. 

A trio, emerging from the nearby neighborhood, furiously pursued insects under the park’s streetlights. I left my car and followed them. Nighthawks, like swallows, feed on the wing, catching insects as they fly. They are strong, agile fliers. I have seen them cut upward, leaning backward as they do, in pursuit of prey. They make micro-adjustments that give them a “tipsy” appearance, as Pete Dunne puts it in his Field Guide Companion. To me, they appear confident in the air. Untouchable, even. Nighthawks always seem to be beyond their human-observer, even when approaching them—a twist of angles always cutting away. Unlike songbirds, which rarely fly directly at people, this trio chased their prey wherever it went, even if it meant flying directly at me. 

An arm’s length away, a nighthawk.  

Photo credit: "Nighthawk at Dusk (Centennial, Colorado)" by Jared Del Rosso
Nighthawk at Dusk (Jared Del Rosso)

One can only seek a trajectory that may someday cross the trajectory of a nighthawk. I spent this past summer seeking just that. I let my dogs lead me. I indulged every detour and delay. We turned home when they wanted to. We inspected dead ends. We doubled back on trails. We lingered when the dogs wanted to linger. We sat together in fields and on curbs. I suppressed my better judgement of where and when the birds would appear. By maintaining the appearance of not seeking nighthawks, I hoped I could fool serendipity into delivering them.

I did so to try to document the bird’s presence in Centennial, a southern suburb of Denver, during the bird’s nesting season. A mid-June sighting gave me hope. My dogs and I sought the birds above a buggy marsh at a local open space. The setting sun inspired the complex chorus of catbirds, blackbirds, and sparrows. But I missed a simpler sound: the buzz of the bird I sought, the distinct, nasal “peent” of a nighthawk. As dusk deepened, my dogs decided it was time to head back to our car. (One dog is afraid of the dark and what it means in Colorado: wild canids. The other is simply not much for walking.) I obliged, though I wanted to keep seeking. 

Nearer to the car, the dogs changed their minds, insisting I let them chase each other around me. Though leashed, the dogs sprinted circles. To keep myself from their tangle, I spun with them. Once, twice, then—and only because the dogs had chosen when to turn back and when to stop for play and when to turn me in the right direction—a nighthawk. 

I seek the nighthawk’s trajectory because I measure the world by this bird. They arrive in Colorado late in spring migration, just as that season tips toward summer. They leave before autumn begins whispering of winter. But the bird isn’t just a sign of the seasons. Their presence speaks of the complexity of our climate, the non-human world, and the human/non-human nexus. Obligate feeders on flying insects, the Common Nighthawk’s steep population decline over the past half-century may relate to broader declines in their prey, owing to pesticide use, the warming planet, and other factors. Nighthawks are losing habitat, too. Some of that habitat is their wild habitat of grasslands and forests. But they’re also losing built habitats in urban and suburban environments. Nighthawks use the flat, gravel-covered roofs of many urban buildings as nesting sites. Unfortunately for the birds, most new development forgoes gravel for other materials, such as rubber. (Patches of gravel, installed on flat roofs, are a potential compromise that may support nesting nighthawks. New Hampshire’s “Project Nighthawk” is experimenting with this.)  

The fate of Common Nighthawks is tethered to us, in ways that the fates of many non-human animals are. But it isn’t easy to observe our entangled destinies. Nighthawks are not like the chickadees that visit our feeders, the finches and phoebes that nest on nooks around our houses, the corvids that seem more at home around our homes than we do, or the hawks that hunt on our highways. Nighthawks nest on our skylines. They migrate at incredible heights, and the vast majority of these birds pass over our summer and fall activities without being noticed. By day, they disappear into trees, grasses, and rocks. Their cryptic feathering renders them invisible. If you’ve ever lucked into a sighting of a nighthawk on a tree, you know how easy it would be to overlook the bird. You also know that nighthawks don’t care that you’ve found them. Their faith in their camouflage, their use of difficult to access perches, and the fact that they have no need for daytime activity allows them to tolerate proximity to us. 

Photo credit: "Perched Common Nighthawk (St. Paul, Minnesota)" by Jared Del Rosso
Perched Nighthawk along the Mississippi River (Jared Del Rosso)

Ultimately, my trajectory and the Common Nighthawk’s did not intersect during their nesting season. Perhaps this is a sign of the species’ decline or of my neighborhood’s hostility, with our grassy lawns and dependence on pesticides, to the birds and their prey. Perhaps it is only that I have not yet found our shared trajectory. 

But I have learned something else from this effort. Pursue this uncommon bird, during the uncommon hours of dawn and dusk, and you will find the trajectory of other uncommon creatures. Those brown bats, one of which dropped me to my knees by hunting at the brim of my hat. A raccoon, ambling down a drainage ditch. A coyote, patrolling an undeveloped field. Fox kits, playfully hunting along a neighborhood path. Great Horned Owls, perched in suburban parking lots and cemeteries. A Mule Deer pair, cautiously watching the human animals who ride bikes, and toss baseballs, and walk dogs while seeking nighthawks in fields near riparian corridors.

This essay originally appeared on the Center for Humans & Nature’s blog.

Featured image by Kenneth Cole Schneider @

Bird-ing? Here’s to the joys of bird-watching

Spring migration is upon us. Here’s to the unique joys of slow birding.

Among the first lessons new birdwatchers learn has nothing to do with birds and everything to do with the people who watch them. Those who are serious about watching birds call themselves “birders,” eschewing the more generally familiar “bird-watcher” label.

I don’t remember when or how I learned this lesson. Certainly, it wasn’t from my field guide. Sibley uses the two words interchangeably, though he seems to prefer “birding.” Dictionaries, too, don’t much distinguish between the two words. Merriam-Webster defines one term by the other — to “bird-watch” is, simply, to bird.

I suspect I learned of the differences from other birders, whether from those I encountered in the field or those that write about birding online. Just google the distinction and you’ll find blogs, essays, and articles expounding on differences that are undetectable in the dictionary definitions of the two.

So what’s the difference? A New Yorker review of the film adaptation of Denver birder and writer Mark Obmascik’s The Big Year distinguished the two in this way: “Crudely put, bird-watchers look at birds; birders look for them.” Yes, but I think the differences are deeper. Writing last year for National Audubon, Freya McGregor described how she often hears birdwatching defined as a more relaxed, leisurely appreciation, while birding focuses on chasing and listing birds, often in a competitive way. Frequently, birdwatching is considered more amateur, while birding’s regarded as more serious and legitimate.

Many of us think of ourselves as birders, not bird-watchers. We do “watch” birds, but watching as a means to an end — identifying bird species, sometimes as many as possible, the “sport” of birding. 

I don’t want to make too much of this. Many birders are excellent bird-watchers, if we mean the simple act of observing birds to understand them better. Many serious birding outings — whether alone or in groups — have moments of long watching, to enjoy the beauty, behavior, or individuality of the birds we see.

Still, allow me to make the case for the particular joys and passions of bird-watching — watching a bird, the bird, closely. In a few moments, I’ll tell you about a bird that has done that for me this winter.

You’ve heard the saying, “Familiarity breeds contempt.” But between species, familiarity is a prerequisite for understanding. The longer we bird-watchers do our thing — watch a specific bird, species or individual — the more likely we’ll get to see birds do theirs. By watching, we may see, hear, and even feel their way of being in the world. “Feel”? Yes,  I’ve had a flock of Bushtits pass closely enough to feel the breeze of all those tiny wings.

Some watchers of birds attend so closely that they even know individual birds, naming specific ones and picking them out of flocks. I am reminded of author Leonard Dubkin and his daughter Pauline naming pigeons in The Natural History of a Yard — and of the great corvid observers Lyannda Lynn Haupt and Bernd Heinrich doing the same with crows and ravens, respectively. I can’t say I know which are the true resident Spotted Towhees in my yard — the Him and Her of that space — and which of the others this winter are their offspring or visitors. I don’t think I’d know the difference if another Northern Shrike suddenly replaced the one I’ve been watching, off and on this winter, at Willow Spring Open Space in Centennial.

Northern Shrike (Jared Del Rosso)

Even if we can’t yet tell a specific individual, we can still detect a lot. Take that shrike, for instance. I’ve noticed that the famously unafraid “butcherbird” can be as withdrawing as any other songbird. A male American Kestrel steals its perch, and the shrike retreats, calling in protest as it goes. (Birds of the World notes that shrikes on their breeding territory will chase off kestrels. But this young shrike is on winter grounds.) And like the American Tree Sparrows also at Willow Spring this winter, the shrike hid away when a male Northern Harrier, the “gray ghost,” coursed through and then above the shrike’s hunting ground.

Northern Harrier (Jared Del Rosso)

One more thing I’ve learned. This particular shrike seems to favor small rodents over small songbirds. Though my observations are admittedly limited, I’ve only seen it pluck rodents from the grasses and weeds. It seems to ignore numerous flocks of Red-winged Blackbirds that fly over. In one hunting attack in the grasses, the shrike landed next to a small flock of tree sparrows yet seemed to ignore them.

Birds of the World offers no clue to this shrike’s apparent preference for rodents. Maybe there are more voles this year. Maybe it’s the other predators. Or maybe it’s simply this: I haven’t yet watched the shrike enough to see its songbird pursuits.

Maybe that’s the point (it’s certainly one of the pleasures) of bird-watching. It forces us to slow down and notice more about where we’re watching birds and what else is there. Certainly, spending 30-45 minutes in one spot, and returning there frequently means less time in other spots, other habitats — and fewer species per outing. But remaining still, in one small patch, widens our view to other things, doesn’t it?

Things like the mammal tracks, the tufts of fur snagged on thorns of wild plum, scat, rodent trails, wasp and spider burrows — not to mention an uncommon or unexpected bird that may happen along as we watch. And also those fall and winter seedy weeds, wildflowers, shrubs and vines, all food sources to be surveyed to see how birds use them, and how that shapes our future bird-watching and birding visits.

Gradually, slowly, but never completely, the places where we bird-watch snap into sharper focus. I’ve known, in a general way, why I see the shrike, the kestrel, the sparrows, hawks, harriers and coyotes at Willow Spring — food, of course. But the gap between knowing that fact and experiencing it in the birds’ everyday actions is as wide and expansive as the open space itself.

One day, might we begin to list bird-watching experiences, observations, and learnings alongside our birding checklists of species and numbers? Stories may be harder to quantify, and eBird won’t be keeping state-level rankings of bird-watchers with the most of them. But bird-watching encounters are no less meaningful than birding ones.

This essay originally appeared in Denver Field Ornithologist’s newsletter, Lark Bunting.

Featured photo by Erik Mclean on Unsplash

“The Night Side of the Woods”: Thoreau’s Whip-poor-will

For Henry David Thoreau, a Whip-poor-will’s call conjured a world we were already losing.

Prior to the 1950s, Americans interpreted the spring arrival of Whip-poor-wills as a sign and not always a welcome one. The birds foretold life and love, yes, but also illness and death. Those more dependent on the earth found something else: a message about impending frosts, storms, and ripened fruits.

After World War II, the Whip-poor-wills had all but disappeared from American consciousness. Sure, we saw a dramatic increase in roads, farms, clubs, and camps named after the bird. But the real thing? It called from ever decreasing patches of woods, often out of earshot of an increasingly indoor and alienated human species.

That is one story of how Whip-poor-wills came to inhabit only the wild edges of America. Another begins earlier by a century or more.

Tuesday, June 10, 1851, was “a beautiful summer night, not too warm, moon not quite full, after two or three rainy days.” The writer of these words, Henry David Thoreau, used the evening to walk to Fairhaven, Massachusetts, by railroad.

As he walked, he found himself farther from towns and his worry that “there would be too much white light, like the pale remains of daylight” on his walk. But he walked deeper into the night and, he writes simply, “it was better.” He encountered Whip-poor-wills and fireflies in meadows, and Nighthawks booming late in the evening.

Deeper into the night, Thoreau encountered fireflies and Whip-poor-wills in a meadow.
Photo by Tony Phan on Unsplash

Thoreau recognized the latter is a rare occurrence, indeed, writing,

I hear the nighthawks uttering their squeaking notes high in the air now at nine o’clock p. m., and occasionally—what I do not remember to have heard so late—their booming note.

Nighthawks are active at twilight; crepuscular birds, these are. It is a truism of their species accounts that they are very rarely active at night and, when they are, it’s usually to hunt insects drawn to artificial light. Perhaps Thoreau misjudged the time? Or perhaps the Nighthawks had been forced down the previous “two or three days” of rain and were making up for lost time.

As for the Whip-poor-wills, Thoreau recognized a broader story in their song. Here was not just natural history, but human history and culture.

The whip-poor-will suggests how wide asunder [are] the woods and the town. Its note is very rarely heard by those who live on the street, and then it is thought to be of ill omen. Only the dwellers on the outskirts of the village hear it occasionally. It sometimes comes into their yards. But go into the woods in a warm night at this season, and it is the prevailing sound. I hear now five or six at once. It is no more of ill omen therefore here than the night and the moonlight are. It is a bird not only of the woods, but of the night side of the woods.

Off hand, Thoreau suggests a tantalizing hypothesis: that the folklore and superstition surrounding the birds matured as everyday encounters with the real birds decreased. Americans once had an intimacy and knowledge of Nightjars born from familiarity. Thoreau is suggesting that, absent this, an unease and anxiety with the night side of things crept in.

In the next passage of his journal, Thoreau further recognized that the aural life of America was rapidly changing: “New beings have usurped the air we breathe, rounding Nature, filling her crevices with sound.”

I’m struck by an irony, as I type this, that I have written this entry with headphones on, a decade-old album filling Nature’s crevices with sound. Outside, this winter, are finches and sparrows, the rustle of towhees in the chokecherry thicket that edges my yard, and somewhere the trill of waxwings.

So to Thoreau’s words, return: “To sleep where you may hear the whip-poor-will in your dreams!”

A Briefness of Bohemian Waxwings

Bohemian Waxwings are having a moment. These far north birds are venturing into Colorado. But what’s brought them here for the first time in a decade?

Bohemian Waxwings are having a moment. This winter, these far north breeders have ventured as far south as Santa Fe, New Mexico. Here in Colorado, Bohemian Waxwings have been relatively common in the Front Range this winter.

It’s been been a decade since Bohemians have been so numerous and conspicuous in Colorado. What’s brought them here? We’ve had deep snow and extreme cold in the Rocky Mountain west. While I don’t know if this has been the case farther north, where this species usually overwinters, one suspects that it is.

But perhaps it’s a fool’s errand explaining the Bohemian Waxwings southward movements. Cornell’s Birds of the World says this of the bird.

Notoriously irruptive, irregularly appearing in large numbers in regions south of normal wintering range. For example, only rarely reported from New Mexico, but in Apr 1959, huge numbers (about 10,000 individuals) arrived in Santa Fe and remained until early May (Ligon 1961). Late arrival at this southern locality suggests individuals moved into the area after depleting fruit supplies in more northern areas. 

At least what we can say what the birds are doing here: devouring the berry-like drupes of Common Buckthorn, an invasive, non-native plant.

Just south of Denver, along the High Line Canal, a single Bohemian Waxwing amid 50-100 Cedar Waxwings quickly became a flock of 30-50 Bohemians among 100-150 Cedar Waxwings.

Today, January 15, that flock tripled in number. For the first time, I had the good fortune of standing amid a large, active, and noisy flock of Bohemians. They filled a small Buckthorn on the Canal’s edge. Dozens occasionally jammed in to my camera’s field of view.

While the photos of these gatherings aren’t particularly impressive, I like how much movement and activity they convey. Waxwings and a robin or too point in every direction. Some are in flight. Others are swallowing Buckthorn. Others are about to collect it. The birds only seem to do one thing in unison: throw themselves into flight, as a single, impressive flock.

Waxwings Gathering in a Buckthorn

When not eating, the Bohemian Waxwings trilled from high perches in the Canal cottonwoods. By comparison to the Cedar Waxwing’s call, the Bohemian’s call is slow and low. Between the robins, Bohemian Waxwings, and a few magpies, the Canal filled with a complex mix of sounds.

Waxwings and the Suburban Landscape

This year, many of the best places to see Bohemian Waxwings near Denver have been south and slightly east of the city, along the High Line Canal Trail. eBird shows that birders have reported Bohemian Waxwings throughout a 4 mile, as a car drives, and 7.5 mile, as the Canal winds, stretch of the trail from southeast Denver through Cherry Hills Village.

eBird Species Map of Bohemian Waxwings sighted along the High Line Canal
eBird Map of Bohemian Waxwing Sightings

The Canal itself is a ditch dug by hand over a century ago. It used to carry water from S. Platte River, southwest of Denver, to the prairies north east of Aurora. Along it, a riparian corridor of cottonwoods, willows, chokecherry, Golden Currants and American plums developed.

These native plants provide important resources to the trail’s wildlife. Cottonwoods, willows, chokecherries, and plums are important host plants for moths and butterflies. These are themselves important food sources for birds during nesting season. Currants, chokecherries, and plums bloom early, providing insects and birds with nectar. The cottonwoods provide nesting habitat for native and introduced species, particularly Northern Flickers, Eastern Screech Owls, and European Starlings.

The chokecherries feed songbirds in autumn; they also serve as host plants for moths and some swallowtail butterflies. Meanwhile, the plums are both a critical host plant for moths and butterflies and an important late autumn food source for mammals, particularly coyotes.

The corridors has also proven a suitable home for weedy and invasive non-native trees and shrubs, particularly honeysuckles, Russian olives, Siberian Elms, and Buckthorn. These can spread voraciously. Tree of Heaven, European Spindle, Privets, the occasional lilac, and Golden Rain Trees, which are overused in landscape plantings, have also begun to move in.

So here in the southern suburbs of Denver and Aurora, our encounters with waxwings happen in a landscape altered by human activities. Meanwhile, waxwings and other birds continue to alter it, spreading seeds of Buckthorn across the canal and adjacent open spaces.

ISO Buckthorn

Birds ignore Common Buckthorn drupes until mid-to-late winter. It’s often the only fruit left standing at this time of year. So to find uncommon or rare birds, it often means being in search of the plant. In addition to the waxwings and robins, I’ve also seen White-throated Sparrows, Townsend’s Solitaires, Hermit Thrushes, White-crowned Sparrows, Song Sparrows, and Spotted Towhees feeding on or associating with Buckthorn.

White-throated Sparrow in Common Buckthorn
White-throated Sparrow in Common Buckthorn along High Line Canal Trail (2017)

All this leaves me with an ambivalence. Rarely do I seek out patches of invasive plants with any kind of joy or hope. But if I hope to find waxwings, I also implicitly hope to find these. And this stretch of the Canal is a wall of Buckthorn. Many of the adjacent yards also have patches of the plant, perhaps owing to the activities of robins and waxwings.

Not to be Ignored, Cedar Waxwings

While Bohemian Waxwing steal the show, Cedar Waxwings are also worth watching. They, too, acrobatically feed on Buckthorn, in Cirque du Soleil feats of balance and flexibility.

Cedar Waxwing on the High Line Canal, Cherry Hills Village, CO

Cedar Waxwing and Buckthorn

Meanwhile, I’ve watched waxwings mellow out the laxative properties of Buckthorn by voraciously drinking. They’ll do this at puddles on pavement, as well as high in cottonwoods, where they gobble up melting snow.

Cedar Waxwings Eating Snow in a Cottonwood
A Cedar Waxwing Munching on Snow

A Cedar Waxwing with Snow on Beak
Cedar Waxwings on the High Line Canal, Cherry Hills Village, CO

An apparent pair of Cedar Waxwing used the snow to maintain their bond, exchanging it as a sort of gift. (Another Colorado birder reported similar behavior between Cedar Waxwings on January 7, and I saw it again on 1/15.)

This “passing behavior” is common during nesting season, when birds affirm their bonds through exchanges of food and water. According to Birds of the World, this behavior is not especially well documented in the winter among Cedar Waxwings: “The extent to which mates associate in winter and migratory flocks is not known.”

However, Bohemian Waxwings display this behavior, according to this 1978 article in Blue Jay, the long-running journal of Nature Saskatchewan. And according to the Birds of the World account of Cedar Waxwings, some pairs do indeed remain bonded beyond the nesting season.

For now, the birds remain committed to the Canal. Eventually, they’ll exhaust it as a food source and look elsewhere. They’re remarkably nomadic birds, after all.

Until then…

waxwing ripen
the winter
Bohemian Waxwing

For more on the remarkable behavior of winter waxwings, see Mary Holland’s incredible post and photographs of a Bohemian Waxwing feeding on Bald-faced Hornet larvae.

In the Field #1: Common Nighthawks

On Friday night (August 12), a group of four or five Common Nighthawks (Chordeiles minor) joined a few swallows in feeding over my home and neighborhood. It’s always something when this happens — the birds flying relatively low, low enough to get good views (but not low enough for good photos).

The visit likely wasn’t a coincidence. Soon after the birds left, I spotted a few flying insects in my yard. They seem to be one of the nighthawks favored late-summer prey, flying ants, though I’m still working to confirm my tentative i.d.

According to the wonderful resource, Birds of the World (subscription required), a 1940 study of the stomach contents of 87 Nighthawks found that flying ants constituted about 25% of the mass of what the birds ate. Flying ants apparently emerge in late summer and, so, are a critical food source for migrating Nighthawks, not unlike late blooms (and feeders full of sugar water) are for migrating hummingbirds.

We’re in the early days of the Common Nighthawks’ southward migration. In past years, I’ve seen them in great numbers (for a suburban environment) in my neighborhood, encountering flocks of a dozen or two or three feeding over area parks. Here’s hoping this year brings the same.

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