Researchers solve mystery surrounding black swift migration
Three Colorado bird researchers have solved a half-century old mystery involving a bullet-shaped bird that nests in Colorado but disappears each winter.
This isn’t a “whodunit” but more a “wheredunit” involving the little understood migration of black swifts, which nest behind waterfalls and in damp caves and grottoes across western Colorado.
Just like all good mysteries, the solution came only after a lot of hard sleuthing, including long stakeouts, daring climbs behind remote waterfalls and pitch-black descents into wilderness caves.
And like every good mystery, the answer both surprises and confounds: The black swift winters in the lowland Amazon jungles of Brazil, more than 4,300 miles from its mountainous summer home.
“This is a real breakthrough,” said Jason Beason, Paonia-based coordinator for the Rocky Mountain Bird Observatory and one of the trio who plugged the hole in the bird’s natural history. “What has captured people’s attention is they didn’t realize we didn’t know where black swifts went in the winter. The black swift is still pretty mysterious.”
The find has so intrigued and delighted the birding world that in March the prestigious Wilson Journal of Ornithology made the black swift story its lead article.
Filling the gap answered the “where” question and also placed the bird somewhere it hadn’t before been documented. Swift-like birds have been reported in South America but nothing was certain until the Colorado swifts were tracked to Brazil.
“It’s amazing we didn’t leave Colorado and were able to establish a new bird species for Brazil,” Beason said.
Black swifts are the largest of the four species of swifts in the United States and are uniquely adapted to cliffs, waterfalls and caves, where they build their nests of mud and moss.
The birds are born to fly, said Dolores veterinarian Carolyn Gunn. Their short, weak legs are built for clinging to steep rock, not perching or walking on level ground.
Swifts have long, scythe-like wings and sleek aerodynamic bodies enabling their acrobatics high in the sky, where they feed on wind-borne insects.
“Their first flight is migration,” Gunn said. “They leave the nest on migration and never come back until the next year.”
Their secluded nest sites, Icarus-like aerial antics and unknown migration give black swifts an allure unlike other birds.
From 1949–58, Owen “Al” Knorr of the Denver Museum of Natural History surveyed black swifts in Colorado and in 1950 first recorded the now well-known black swift nesting colony in Box Canyon near Ouray. Knorr found an estimated 80 nests at 27 sites in Colorado but after he finished, only six more colonies were discovered over the next three decades.
That changed beginning in 1993 when Kim Potter, a wildlife technician for the Rifle Ranger District of the White River National Forest, began studying black swifts after the bird was listed as a sensitive species by the Forest Service.
“I quickly became hooked on them,” Potter said. “Here was a bird with really specific nesting requirements and we couldn’t even tell male from female.”
Through that early support from the Forest Service, Potter has been credited with instigating the current round of black swift research. Today more than 100 nesting sites, about half of all known, are found in Colorado.
Potter also knew the mysterious bird would appeal to the late Rich Levad, a retired English teacher from Grand Junction Central High School who died in 2008 but not before devoting much of the last 15 years of his life to black swifts, which he soon dubbed “the coolest bird.”
So intrigued was he, that the last four years of his life were spent writing “The Coolest Bird: A Natural History of the Black Swift and Those Who Have Pursued It.”
Levad, in turn, introduced Gunn to black swifts.
It was Gunn, after a restless night in her tent during a black swift survey, who devised a way to track black swifts using geolocators originally designed to follow large sea-going birds.
Geolocators measure length of daylight and from that can be determined latitude and longitude.
But even songbird-sized geolocators wouldn’t fit the short legs of a black swift, so Gunn improvised a tiny backpack harness using Teflon tubes above and below the bird’s wings.
In 2009, four swifts were trapped, one near Ouray and three from a cave in the Flat Tops Wilderness, and fitted with the mini-geolocators.
And then the researchers hoped they could find the backpack-wearing birds again.
“I had to put it out of my mind,” Gunn said, “or I’d fret about those birds all winter.”
One thing in their favor: black swifts return to the same nesting sites and even the same nest year after year.
Incredibly, three were recaptured the following year.
“We were ecstatic,” Gunn said. “We had no idea if we were going to see any of the birds again. It was very much beginner’s luck.”
But why are cliff- and cave-dwelling birds wintering in the jungles of Brazil?
“We were really surprised because the lowland rain forest has very little topography,” Beason said. “But there are some waterfalls and cliffs down there, so that would be good places to start the search.”
Search, as in search for answers to more mysteries about the black swift.
Do all North American swifts migrate to Brazil? Or do some head to Peru or Colombia, where black swifts have been reported but not verified?
Where are their nests, or do they simply “aerial roost,” heads tucked under while flying in wide circles, virtually asleep on the wing?
“Every time you answer one thing you get 10 more questions,” Potter said.