Out of the Shadows: Black Swifts, North America's Most Mysterious Birds
Whether exploring dark, wet caves in Colorado or crossing paths with Montana's grizzlies, a dedicated band of scientists and volunteers is determined to solve the mystery of one of the most elusive birds on earth.
As the sun sinks into the sky on a warm August evening, a black swift nimbly plucks flying ants out of the air. The balloon-like bolus at her neck bulges with the insects, which she’ll soon feed to her hungry chick hidden away in a mountain cave. Her scythe-like wings and torpedo-shaped body blink in and out of view as she rockets toward a 1,500-foot-deep canyon here in western Colorado’s Flat Tops region, where 10,000-foot-high plateaus are riddled with water-carved caves. She’s heading for one of them: Fulton Resurgence Cave, a teardrop-shaped cavity high on a cliff. Water pours from its mouth, bathing the vibrant green moss and algae growing on the walls in mist as the stream cascades into a steep gulch. It’s the sort of place only spelunkers—or possibly hard-core birders in search of the continent’s most mysterious avian species—would venture.
The swift makes a tight circle before zipping inside, where her downy chick waits in the dark on a teacup-sized moss nest built on a narrow ledge high above the cave floor. Four more ravenous chicks sit in nests on their own ledges in other parts of the cool, wet cave. The soothing sound of the rushing stream fills the air. These only children—black swifts, unlike the three other North American swift species, lay just one egg—are all safely out of the reach of predators.
Tonight, however, the mother doesn’t make it inside. Instead she’s snagged in a mist net strung across the opening.
“Oh, our first adult!” exclaims Kim Potter, a biologist with the U.S. Forest Service’s White River National Forest. Her short silver hair pokes out from beneath a rock-climbing helmet, and her black fleece jacket wards off the cool air flowing from the cave.
Since 1998 Potter has made the arduous trek here once a year to monitor the birds. Her intrepid partners include Carolyn Gunn, a Colorado Parks and Wildlife veterinarian who volunteers on the swift project, and Jason Beason, the Rocky Mountain Bird Observatory’s special monitoring projects coordinator. Also along for the adventure is local photographer Todd Patrick, who has taken hundreds of pictures of the birds and researchers during the past several years. To reach the cave, the group hiked for three hours, losing 2,000 feet in elevation over three miles before covering the final 150-foot drop along a scree-covered slope to the cave hidden below. They’ll make the even more grueling return trip in the dark, using headlamps to follow their trail.
This afternoon they banded the chicks, using an 18-foot ladder they keep stashed nearby to reach the lofty dwellings. Now it’s 7 p.m., and the adults are beginning to return. “From dusk to dark it’s pretty much rush hour,” says Potter. She jumps up, nimbly crosses the jagged rocks like the long-distance trail runner she is, and disentangles the bird in a few seconds. While she and Gunn examine the swift, Beason crouches near the net, watching for the next captive.
“She’s nice and healthy-looking,” Potter says, blowing on the bird’s belly to ruffle the feathers and expose a visible layer of fat. Lustrous gray-black body feathers fade to light gray on the face. She has enormous black eyes and a petite nub of a beak. Her curved wings measure 6.5 inches each, and, at an ounce and a half, she’s astonishingly light. Referencing the leg band against a log—ID number 096103486—Gunn gives a little squeal. This female, which they’ve captured here yearly since 2008, helped solve the mystery of one of the bird world’s greatest vanishing acts: where black swifts disappear to in winter. In 2010, for the first time ever, the researchers tracked this and two other birds’ incredible 8,600-mile round-trip journey to lowland rainforest in northwestern Brazil—a country where the species had never before been documented. “These birds are just incredible, absolutely the coolest, most mysterious birds,” says Potter. “For every question we answer, 10 more pop up. There’s so much we don’t know, and we can’t really know how to protect them until we better understand them.”
The clock is ticking as a small but passionate cadre of professional and citizen scientists race to uncover the black swift’s secrets. Throughout the West these researchers are hiking to remote waterfalls and caves, bushwhacking through grizzly country, and scaling slippery cliffs in search of more nesting sites (only about 200 have been documented). At the same time, they’re employing cutting-edge genetic tools and strapping tiny geolocators on the birds to shed light on such basic questions as whether all black swifts winter in the same area and if different colonies mix.