Distribution: The black swift, Cypseloides niger, occurs in mountainous regions of the western United States and Canada. The only subspecies that breeds in this range is Cypseloides niger borealis, other subspecies occur in Mexico/Central America and in the West Indies. Little is known of the historic range. Currently, black swifts occur in three widely separated areas: central Colorado through central Utah; central and southwestern coastal California; and southern Alaska to northern Washington and inland to southwestern Alberta, northern Idaho, and northwestern Montana. Abundance varies greatly among and within the 3 subpopulations. In the northwestern subpopulation, black swifts are fairly common to locally very abundant (Chantler and Driessens 1995); in California the swift is a local and restricted breeder (Foerster and Collins 1990); in Colorado black swifts are uncommon (700-800 pairs)(Boyle 1998) and in Utah they are extremely rare (Knorr 1962).
Only 2 confirmed breeding locations are known in Utah: the Bridal Veil Falls area and the Aspen Grove area (Knorr 1962). Other possible breeding areas where birds have been seen or collected include Weeping Rock in Zion National Park (Wauer and Carter 1965), Doughnut Falls in Big Cottonwood Canyon (Wheeler unpublished data), and Pete's Hole in the Manti-La Sal National Forest (Howe 1998). Stewart Falls near Sundance has also been reported as a possible breeding area (Behle et al. 1985). Sighting records also exist for the Salt Lake City area, Red Creek near Fruitland (Hayward et al. 1976), and Upper Provo Falls near Mirror Lake (Shirley pers. comm.). Additional breeding sites are possible in Utah, particularly in the Uinta and Wasatch ranges, where the proper habitat conditions exist (Knorr per. comm.). In Colorado, Knorr (1961) found 27 active colonies in the high Rockies, including 12 colonies in southwestern Colorado approximately 80 k (50 mi) from the Utah Border. Wintering range of the black swift is thought to be Central America, possibly into northern South America (Chantler and Driessens 1995).
Ecology: Black swifts are one of the latest migrants and one of the latest breeders in Utah. They arrive in late May or early June and may still be tending nests in early September. Swifts probably start their southerly migration in mid to late September, but may remain in the state until October. Black swifts are aerial insectivores and feed exclusively on flying insects. They generally forage thousands of meters above the ground, but may also forage low over rivers and streams. Foraging forays last throughout most of the daylight hours, and swifts may forage up to 40 km (25 mi) from nesting colonies. Black swifts usually forage in flocks, often with other species; they also migrate in flocks (Chantler and Driessens 1995).
Black swifts nest in small colonies (usually less than 10 pairs) near and often behind waterfalls at middle (1820 m [6000 ft]) to high elevations (> 3500 m [11,500 ft]). Both courtship and copulation occur while in flight. Nesting sites are used traditionally and adults are long-lived. Collins (1995) reported capturing an individual at same the colony 9 years after its initial capture. Nesting habitat is classified as mountain riparian (Behle and Perry 1975); however, waterfalls are the key characteristic of nesting sites. Nesting sites typically exhibit 6 ecological characteristics: water (waterfalls), high relief (cliffs), inaccessibility to humans and predators, darkness, unobstructed flight paths (Knorr 1961), and ledges or cracks (for nest placement) (Knorr pers. comm.). Nests are on ledges, cracks, or crevices and are often behind or in the spray of waterfalls. The nest is constructed of moss, algae, and ferns, and contains little or no mud. It is often lined with conifer needles or rootlets (Knorr 1961, Ehrlich et al. 1988). Nests are often reused after addition of new layers of material. Typically only 1 egg is layed (sometimes 2) in mid to late July; both adults incubate the egg for 24-27 days. Nestlings are altricial and develop over a period of 45-49 days; both adults feed the nestlings. Since adults forage during the day, nestlings are not fed until dusk and may be fed throughout the night (Knorr pers. comm.). The black swift's nesting period (egg to fledging) is extremely long for a bird of its size, and is similar to the nesting period of many buteos (hawks approximately 4 times the size of a swift).
Habitat Requirements: Black swifts require waterfalls for nesting; typically the falls are permanent but may be intermittent if they flow throughout the breeding season (June to early September). Nesting sites are typically surrounded by coniferous forests, often mixed conifer or spruce-fir forests, but this varies depending on elevation and aspect, and nest sites may include mountain shrub, aspen, or even alpine components. Streams that create the waterfalls are typically mountain riparian habitats.