The Black Swift (Cypseloides niger) has an extensive albeit somewhat disjunct range in western North America from southern Canada south to southern California (Foerster and Collins 1990) and Arizona (Knorr 1989) and east to Colorado (Knorr 1950, 1961). Its range in the Great Basin has been unclear. I found several breeding colonies on the eastern margin in Provo Canyon, Utah (Knorr 1962), but until 1986 my subsequent attempts to locate Black Swift colonies elsewhere in the Great Basin were unsuccessful. Even so, observations by Ridgway (1874) suggested that there might be other sites located along the western margin of the Great Basin.