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Mystery of the rare black swift

Photo by Aaron Maizlish/Flickr.com A black swift on a nest at Box Canon Falls, Ouray, Colorado..

I was leaning far back in my camp chair with my binoculars glued to my eyes trying to follow a migrating hawk that was little more than a speck in the ether.

As I struggled to identify the hawk without falling backward, another speck nearly as high rocketed across my view. With the hawk forgotten, I attempted to follow and identify the new bird as it hurried south.

The speedy bird was a black swift, one of Oregon’s rarest and least known breeding species. There may be fewer than a dozen pairs breeding in the state. True to its name, it is almost entirely black, and it’s the largest swift breeding in North America. It is a strong flier and traverses more than 200 miles a day in migration. From what I observed, this bird would have no problem meeting that goal.

For years ornithologists and naturalists wondered why they weren’t found in Oregon. As of 1940, only a single specimen had been found in the state, a dead bird recovered in the Willamette Valley. They breed to the south in the Sierra Nevada and along the coast of California in modest numbers. They are relatively common to the north in southern British Columbia and the north Cascades of Washington. They also breed in Colorado. Why not Oregon?

Apparently, we have a shortage of the special nesting habitat they require. They nest in crevices on rugged cliffs, most often near water. One of their favored nesting spots is behind waterfalls, where they lay a single white egg. The falls provide a cool and protected refuge. For the world travelers among you, the great dusky swift is a close relative of the black swift and is famous for its abundance and show at Iguazú Falls in northeastern Argentina.

Black swifts were finally discovered nesting in Oregon at Salt Creek Falls in Willamette Pass. It remains the most reliable place to see these birds in the state. If you know anything about the mountain lakes along the eastern slope of the Cascades between Santiam and Willamette passes, you know late spring and early summer belong to the mosquitoes. On days when a breeze is blowing from the west, the best place I have found to observe these birds is at the east end of Odell Lake, where the swifts line up to collect the bounty blown off the lake.

At other times they forage at great heights well above swallows and other swifts pursuing insects drawn upward to great heights by thermals in the heat of a summer day.

It was long an ornithological mystery where these birds wintered. The tropics harbor several similar species, making it hard to identify swifts as they fly high above the dense forest canopy. Only in the last 20 years did researchers tagging birds with a tiny device called a “geolocator” finally discover their winter quarters in western Brazil in the Amazon Basin.

Locally, it is suspected they have nested at Mill Creek Falls near Prospect. Other places you might see them are along the coast or the mountain lakes like Howard Prairie (when there is water) during spring or fall migration.

Stewart Janes is a retired biology professor at Southern Oregon University. He can be reached at janes@sou.edu.