Montana Audubon researcher Bo Crees and I spot a black swift darting into the misty spray of the waterfall spilling down above us. We’re surveying a site in the Bitterroot Mountains.
It’s just a moment until the dark bird disappears into the mossy overhang.
“And that’s why, 'if you blink, you miss them,' is something we say a lot with black swifts,” Crees says.
In the half hour we’ve been standing here, Crees’ eyes have been glued on the rocky walls around the falls. He’s spotted several pairs of swifts as they plummet from the sky and swoop up under the water. The birds fly out every morning around sunrise to spend the day catching bugs, and then return at dusk to feed their chicks.
Swifts are like goldilocks, they need a waterfall with just the right amount of flow and mossy overhangs to build a nest.

"Notice how perfect this nest location is, safety wise. The nest is probably about 20, 25, feet above the creek," Crees points out.
The nest he points to sits on a tiny ledge under a horizontal rocky roof. Multiple pairs of birds can nest under the same waterfall. Crees will count at least three groups before the night is through. Black swifts only raise one chick in a nest per year. These watery locations are ideal, because they’re almost impossible for predators to access.
"This is why the swifts can afford to take a really, really long time to incubate the egg and then tend to the young before they fledge," Crees explains.
But waterfalls aren’t steady. As climate change alters snowpack, changes the timing of spring runoff and prematurely melts glaciers that feed these falls, swifts lose nesting sites. Their population is less than half the size it was 50 years ago. The Cornell Lab of Ornithology has labeled the black swift as a “tipping point” species.
"Swifts, as soon as they leave a past nesting site because there’s no more water or moss or what they need for nesting, it’s kind of unlikely that they’re going to repopulate that site," Crees says. "Even if in future years we start getting more moisture."

Montana Audubon researchers, like Crees, have been surveying waterfalls for swifts for over a decade. This summer, they’re covering more than 30 sites from far north in the Yaak to down here in the Bitterroot. Glacier National Park has the highest density of survey sites, with the most waterfalls.
Researchers are using this data to better understand where the birds are, and to track how swifts are responding to climate change. After finishing tonight's survey, Crees will return in the morning and then another evening after that, to get the best idea of how many swifts are nesting here.
As he hikes out, and the background noise recedes, Crees marvels at what it must be like to enter the world right next to a waterfall:
"I always think about the moment that a black swift fledges after about a month and a half of knowing nothing but waterfall noise, and all of a sudden they're on the wing and everything becomes quiet instantly."
