In arid southern Colorado, a vast valley floor is walled in by the formerly volcanic San Juan Mountains, and violently uplifted Sangre de Christo Mountains. Once a mighty lake, the valley floor is now arid sagebrush, cut in two by a lush strip of marsh and cottonwood arroyo along the meandering Rio Grande River. Over thousands of years, prevailing southwest winds drove volcanic sediments from the San Juans, and flung sandy sediments—left behind from the lake—across the valley. Wind carried the sediments until it could bear the burden no longer, dropping them in a crook of the Sangre de Christos. With southwest winds seeking to cover its foothills, the Sangre de Christos fought back with lesser storm winds. This pushing from both sides lifted piles into small mountains, resulting in the highest sand dunes on the continent: the Great Sand Dunes, covering 72 km2 (~30 mi2). The sand deposits in entirety cover a much larger area, about 553 km2 (210 mi2; National Park Service 2020).
High above the dunes, it’s from moody mountain passes and dismal dark canyons the winds came to form the structures so tall they can be seen from far across the valley plains. A day spent on the hot dunes is what inspired the seeking of repose in the cool canyons; where sunlight is scarce. An afternoon visit served its purpose: feet numbed by a frigid stream below a thundering falls. A sunrise visit the next day served its purpose too. In sight of the great dunes, not yet kissed by the morning sun, a rock-strewn road wandered through sagebrush. Where the day before there had been far too many vehicles that did nothing but struggle across the rock, there was then loneliness in the sacred, thought-provoking sense. The three-mile climb took half an hour if you were going as fast as possible, but this day I had to stop and bask in the serenity. Though the sun had not yet crested the Sangre de Christos upon which I climbed—and it wouldn’t for some time—the wildlife was very much awake. A pronghorn darted across the road, chased by some unseen creature; either phantom or alive. In its wake, a small flock of bouncy Mountain Chickadees came to life among the junipers.
Sun still quite behind the jagged peaks, I began to climb further, this time on foot. A trail cut through stunted pinyon-juniper forest was rich. Rich with the smell of evergreen and rocks crunching underfoot. Rich with avian life. Not long after leaving the car, I heard innumerable pit, pit, pits and tsip, tsip, tsips ahead. They were the contact calls of Bushtits, talking to each other as they foraged. Among them, more Mountain Chickadees called in a dialect just different enough from the Carolina Chickadees back home. I found myself in a whirlwind. Bushtits buzzed around me, constantly in motion. I made a soft, but alarming sound through my teeth; something us birders do to keep birds interested. Chickadees scolded, while Bushtits came so near I could have plucked one off the tree. I had a close study in the small, gray birds. Don’t be fooled by their grayness. What seems monochromatic from afar, is in fact offset by a subtly masked brown face; even pale eyes in females.
I spent much of the morning among this flock, relocating it several times. Bushtit and chickadee alike cared nothing of my presence, foraging in juniper amongst powder-blue berries.
The observant naturalist never gets anywhere fast. As I backed away from the Bushtits, I caught the catlike mewing of a Green-tailed Towhee. Not a nemesis per se, as I’ve seen them before, but they have too often provided only fleeting glimpses. Their lifestyle is not one of the obvious, but of the obscure. You might think it hard to hide this cardinal-sized member of the sparrow family, but I’ve often heard them at close range and never managed to locate the perpetrator. A neat gray breast and clean white throat draw the eyes in and up to a surprisingly chestnut head, and green-yellow feathers covering not only the tail, but wings and back too. I must have entered the territory of a family group, as there were at least three circulating about a juniper and nearby pinyon pine. One, a true friend, perched for what must have been a full minute, allowing the best view I may ever have.
Looking over my shoulder, the sun was now shining on the dunes below. Glowing orange on the sun side, dramatically shadowed on the other. Where I was perched, though, the sun had yet to reach.
While savoring the view, I must have startled a local resident. Another catlike mewing, this one harsh and questioning, alerted me to the presence of a Spotted Towhee. Among the sage-green vegetation, I spotted this bird easily. Its white underside, rusty flanks, and black upperparts prevented it from being well camouflaged. It isn’t hard to see why this species—and their close eastern cousins—were once collectively known as Rufous-sided Towhee. Like Eastern Towhees back home, the western Spotteds drop my jaw at every meeting. Cousins separated by the Great Plains for most of the year, a select handful of Spotteds creep further east, occasionally wandering into western Arkansas where I and the Eastern Towhees call home. They’re set apart from the locals by sound and white speckling on the shoulders and upperside. Back on the mountain slope, I thought I’d scared this skulker into the brush, but was pleasantly surprised when it perched for just a moment, foraging among juniper boughs.
The brief, but birdy hike brought me to the canyon’s mouth, where the talking stream began to drown out other sound. The narrow slot was the reason I had come. Its walls, steep and damp, were used by Black Swift for nesting and roosting. Now late in the season, all that remained were disused nests and a few lingering handfuls of the swifts. At least, so I had heard. I had also heard that the canyon’s mouth was the place to be. Early in the morning, the swifts leave the roost to spend the day wheeling acrobatically, foraging at a much higher altitude than other birds; often completely out of sight and miles from roosts (Lowther et al. 2020). Before sunset the previous evening, I spotted a trio twirling low above the foot of some dunes in the valley. Without binoculars or camera, I was only partially satisfied. Now on a full-blown swift pilgrimage, I waited patiently in the cold morning shade near the even colder stream, its headwaters somewhere high above treeline to my east. Seven o’ clock came and went. So too did seven-thirty. As the sun began to pass the peaks above, creeping unceasingly towards my position high on the slopes, I worried I had not woken up early enough. Impatient, I edged carefully along the cold stream and entered the canyon. The only trace of daylight was a narrow strip of blue sky above me, otherwise dark walls closed in. Nervous that something unsavory could be just around the corner taking a morning sip from the water, I nevertheless continued; first to the left, then to the right, teetering on rocks to avoid the cold depths. I scrutinized each bump along the walls and every shadow I thought I saw out of the corner of my eye. One final and sharp turn to the right and the canyon ended at a thirty-foot falls. Its cool mist was welcome after the heat of the hunt.
Retracing my steps, I again scoured the walls. Near the mouth, a shadow that was more than my imagination brushed past and came to a stop atop a boulder in the stream. I knelt instinctively behind another boulder. Though I knew it wasn’t a swift landing near the water, I was curious as to what denizen of the shadowy canyon this was. Shades of gray, long tail, a high mountain thrush. This was a Townsend’s Solitaire. Its scaled, rather than uniform, breast rendered it a young of the year. Several times I watched it drop down to the water. Behind its boulder and out of sight, I was left to imagine what it might be doing: drinking? bathing? foraging for invertebrates?
One last look along the walls and I exited. The tight-lipped canyon had kept its primary secret, but divulged others. My watch told it was now nearly eight. At a loss, I walked back to the streamside opening where I had previously waited. Looking into the sky, back at the canyon, onto the valley below, I saw no birds resembling a swift. One final, incredulous look back at the canyon and I spotted a dark object moving fast through the trees. My eyes could barely keep up. The bird slingshotted within feet of my face, leaving me spinning towards the valley view. For a blessed few seconds my binoculars were filled with a single Black Swift. Hooked wings and cylindrical body, uniformly dark, whirled tauntingly ahead before dropping out of sight. It was gone. I was in awe. What a creature. I waited for others, up to fifteen of which had been present just a few days before, but the canyon was still and silent.
Black Swifts are one of the last frontiers in North American ornithology. Their entire lifestyle is a void. From Honduras to British Columbia, their breeding range extends patchily along the American Cordillera. Populations also exist in the mountainous Caribbean, maybe breeding, maybe year round. They nest in high mountain fortresses, protected by steep canyon walls and shrouds of lacy, crashing water. Often the swifts nest and roost in the damp spray, young growing up cold and wet. Some populations are completely inaccessible. The location I had visited was one of the easier ones. Once breeders leave for winter, their destinations are unknown. A single, groundbreaking study identified wintering areas for three individuals captured in Colorado and released with geolocators, a tiny device that logs location data. The tagged swifts ended up in western Brazil; not in high in the Andes, but in lowland rainforest (Beason et al. 2012). Fast flocks of migrants and occasional specimens are the only other clues suggesting Black Swifts migrate through Central America to winter in South America. That is the extent of current knowledge (Lowther et al. 2020).
At the canyon’s mouth, dumbstruck from the swift encounter, I began to perceive the pronghorn’s phantom. The hairs on my arms stood up as I imagined something watching me from the mats of juniper, still in morning shadow. While it was probably nothing, the rocky Sangre de Christos do hold mountain lions as one of their many secrets; prowling for me, prowling for antelope that stray too far from the plains below. I can’t say I wasn’t happy for the timely arrival of a human family, out for an early morning hike. Solitude broken, I shook off the fog of swifts and shadow-creatures and headed downslope.
Along the way, I relocated my friendly Bushtit flock. Perhaps I’d missed them earlier, or perhaps they had gained in number, but among them were new companions. Again from close range, I watched the flock forage. Out from the gray mass, a dainty yellowish bird came: an Orange-crowned Warbler. Largely a uniform yellowish-green, I have seen the namesake few feathers only once out of the many individuals I’ve spotted in my time birding. This one was no different. It perched inquisitively before me and resumed foraging.
Among the flock too was a Red-breasted Nuthatch, first given away by its nasally yank, yanking. I spotted it among the cones of a pinyon pine, upside-down as usual, checking for seeds and small insects.
The stunted forest had really come alive, most of it now well within the rays of the morning sun, as it warmed slope and valley, driving out the cold of the night. Continuing down I was surprised by a familiar sound, if not of a slightly different accent than back home. The complex song led me to a duo of Warbling Vireos. One individual sang a single verse and was silent; likely a figment of the late season.
Near the car, a Townsend’s Warbler streaked past, followed close behind by a Black-headed Grosbeak. These two colorful birds played hard to get, but led me into the clutches of a Virginia’s Warbler and several Western Tanagers, now drab with nonbreeding color. These were my goodbye birds, the ones that saw me off as I traversed back down the rocky road.
Literature Cited
Beason, J.P., C. Gunn, K.M. Potter, R.A. Sparks, and J.W. Fox. 2012. The Northern Black Swift: migration path and wintering area revealed. Wilson Journal of Ornithology 124:1-8.
Lowther, P.E., C.T. Collins, C. Gunn, J.P. Beason, K. Potter, and M. Webb. 2020. Black Swift (Cypseloides niger), version 1.0 in Birds of the World (S.M. Billerman, editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.blkswi.01
National Park Service. 2020. Great Sand Dunes: Geology. <https://www.nps.gov/grsa/learn/nature/sanddunes.htm>