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Black Swift

April 2018 Bird of the Month

Black Swift          Cypseloides niger                                   Andy McCormick

Length  7.25”   Wingspan  18”   Weight  1.6 oz (45 g)    AOU Alpha Code BLSW

 

The largest swift in North America, the Black Swift is seldom seen, because it flies at high altitude. However, it can be seen more easily, when it flies lower on overcast days.

Graceful Glider and High Flyer

The Black Swift is known for speedy, graceful flight with a burst of wing beats followed by long, tacking glides. The wings are evenly bowed and the long, narrow wings uniformly taper to a fine point (Dunne). The wing beats are stiff, which separates the Black Swift from swallows. The tail is slightly forked in flight.

This swift can cover long distances in a short time and will forage far from its nest. Typically, the Black Swift leaves its roost and will be airborne for the full day until it returns at dusk. The swifts forage at high altitude on swarms of flying ants. On cloudy days they are more likely to forage at lower altitudes on paper wasps, flies, and other insects (Lowther and Collins).

The more common Vaux’s Swift is smaller and has shorter wings, more rapid wing beats with little gliding (Alderfer).

Lover of Waterfalls

The Black Swift has an affinity for nesting behind or near waterfalls and on other damp cliffs. The first Black Swift nest was discovered in 1901 on the sea cliffs at Santa Cruz, CA by A. G. Vrooman. However, skeptics would not accept his finding until 1914, when he showed another nest to a colleague. Because its nests are so hard to locate, there is little scientific study of the Black Swift. 

Researchers have located only about 100 nest sites in North America. The Black Swift prefers a damp, secluded cliff inaccessible by predators (Kaufman). Nests have been found along rocky coasts and interior mountain passes.

You can have a rare look at a Black Swift nest site in Colorado with a bird on the nest at the Macaulay Library . There are a number of other videos in the library showing the bird adjusting her egg, changing her position, and looking around the area.

One Egg

The Black Swift builds a shallow nest of mud, moss, and ferns and only one egg is deposited. Incubation lasts a little over three weeks. Both parents feed the young bird for about seven weeks until it is ready to fly. The parent can be away from the nest for 3-7 hours. During that time it accumulates insects in its esophagus using saliva to create a bolus. Upon return to the nest the bolus is fed to the young swift in a series of regurgitations. The young fast most of the day, but are fed in increments during the night (Lowther and Collins).

Black Swifts have been observed in the Pacific Northwest, in mountains of Colorado, and in Mexico and Central America, and they are known to breed in these areas. However, little is known about where they go after breeding and how far they migrate. The genus name derives from the Greek kupselos, the swift, and the species name niger is Latin for black (Holloway).

 

black swift by Amy McAndrews

Photo credit Amy McAndrews. References available upon request from amccormick@eastsideaudubon.org.

 

 

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