Black Swifts make way onto Brazil birding list
A bird that summers in Colorado but kept secret its winter home for 165 years now has become one of the latest additions to the Brazil bird list.
High-flying Black Swifts, scimitar-winged birds which often nest on vertiginous cliffs behind waterfalls and in dark, blade-thin canyons, have been familiar though rarely seen summer visitors to Colorado and the Western U.S.
However, when Black Swifts migrate, they leave little evidence as to their destination.
In 2009 three researchers in Colorado — Kim Potter of the U.S. Forest Service, independent researcher Carolyn Gunn, and Jason Beason of the Rocky Mountain Bird Observatory — trapped four Black Swifts and attached light-level geolocators to them.
This technology, similar to that used by early navigators, measures ambient light levels, recording periods of day and night to establish geographical position.
Against considerable odds, three of the four birds were captured again in Colorado the next summer and data from the geolocators indicated the birds had wintered in the lowland rainforests of western Brazil.
Beason wrote about the discovery in the March, 2012 issue of the Colorado Field Ornithologist journal and he subtitled the article “How to discover a new bird species for Brazil without leaving Colorado.”
Now, that upbeat claim has been justified.
In a recent email, Beason said the Brazilian Committee on Ornithological Registers has added Black Swift to the official Brazilian bird list based on information from this research.
“The Black Swift along with Madeiran Petrel and Desertas Petrel have been added to the ‘secondary list’ for Brazil,” wrote Beason.
A secondary listing, said Beason, means “there is no documentary evidence (i.e., skin, photo, video, sound recording) to confirm presence.”
He said the two petrel species, small seabirds native to a chain of islands off the coast of Portugal, were also followed to Brazil using tracking devices.
When the study was released, Bob Altman, wildlife biologist with American Bird Conservancy and coordinator of Black Swift monitoring in the Pacific Northwest, said it solved “one of the last major mysteries left in ornithology — where black swifts spend the winter.”
Beason said Black Swifts also were traced to Peru but so far that country hasn’t accepted the incomplete data.
“The problem is the other species of the same genus are extremely difficult to tell apart and they probably won’t get a photo definitively showing a Black Swift” in Peru, Beason said. “They’ll have to find or capture a bird to be certain.”
In the tropics, “capturing” a bird often means shooting it, in the style of John James Audubon.
Beason said he helped put geolocators on two Black Swifts last summer in northern Idaho.
“We’ll use the geolocators to see whether other Black Swifts in North American overwinter in the same location the Colorado birds were tracked to,” he said.
Although there is some degree of luck involved in re-capturing the same bird in following years, Beason said Black Swifts might be easier to re-capture than other species because they have a high degree of fidelity to nesting areas.