Black Swift Breeds in Utah
Black Swift Breeds in Utah.-A ten-year study of the geographical and ecological distribution of the Black Swift (Cypseloides niger) in Colorado (Knorr, Wilson Bull., 73, 1961: 155-170) resulted in the discovery of 27 active breeding colonies.
The Black Swift is not known to occur in the vast area between the Colorado Rockies and western Nevada, so it seemed desirable to search this area for the purpose of adding to the meager knowledge of the species. I chose to begin in the Wasatch Mountains of Utah because the precipitous nature of these mountains and my experience with the bird led me to believe that it should breed there.
Bridal Veil Falls in the Provo area seemed a likely spot to begin since the term “Bridal Veil” as applied to waterfalls is descriptive of the Black Swift’s nesting environment. I went first to the Aspen Grove Recreational Area east of Mt. Timpanogos and immediately upon arrival I saw Black Swifts sailing around in the air above Aspen Grove in the company of White-throated Swifts (A?ronautes saxatalis). Here behind a thin cascading falls two Black Swift nests were discovered, each containing a feathered young bird. The size of the colony is unknown.
Four more sites were located farther down Provo Canyon. One was located at Upper Falls and one each at the two cascades between Upper Falls and Bridal Veil Falls. A nest in the colony at Bridal Veil Falls was visible from the tourist parking area on Highway 189 below the falls.
All the nests were found on August 22, 1959, and nests were observed again during the summers of 1960 and 1961. Everything about the sites seemed typical except that the nests appeared to have more fern incorporated with the moss than nests in Colorado. I do not believe this discovery constitutes a breeding range extension because Black Swift breeding sites are ancestral by virtue of their unique and narrow ecological requirements. Unless one knows how and where to search, the bird can be entirely overlooked.-OWEN A. KNORR, Department of Biology, University of Colorado, Boulder, Colorado, July 1, 1961.