Black Swift

The Black Swift is a large, entirely sooty-black swift with long, broad-based wings and a slightly forked tail; some individuals show fine whitish speckling on the forehead, but overall it appears nearly uniform dark at a distance. It is the largest swift regularly found in North America and one of the least-known North American breeding birds due to its extremely remote and inaccessible nest sites.

It nests almost exclusively on damp cliff ledges directly behind or beside waterfalls, in sea caves along the Pacific coast, or on other precipitous, wet rock faces—habitat that is difficult for researchers to access, which long obscured basic facts about the species, including its wintering grounds in the Amazon basin of Brazil, only confirmed via geolocator tracking in the 2010s.

Key field marks

• Large size (largest North American swift)
• Entirely sooty black, sometimes with faint whitish forehead speckling
• Slightly forked tail, long broad-based wings

Similar species

• White-throated Swift: bold black-and-white pattern, smaller.
• Vaux's and Chimney Swift: smaller, browner, more uniformly cigar-shaped without the forked tail.
• Swallows: broader-winged with less stiff, more fluttery flight and different tail shapes.

Range and habitat

Black Swift breeds very locally in western North America—from British Columbia and Alberta south through the western US to Mexico and Central America—and in parts of the Caribbean, nesting almost exclusively at sites with high humidity and inaccessibility, such as ledges behind waterfalls, sea caves, and steep, wet cliff faces.

Migration

A long-distance migrant; satellite and geolocator tracking has shown that North American breeders winter in the Amazon basin of western Brazil, a discovery made only in the past couple of decades.

Behavior

Forages high in the air, sometimes ranging many kilometers from the nest site in search of swarming insects, and can travel long distances ahead of approaching storm fronts to find better feeding conditions.

Voice

Generally quiet; soft twittering notes are given occasionally near the nest site.

Feeding

Specializes on swarming flying insects, particularly flying ants and termites, taken in aerial pursuit, often far from the breeding cliffs.

Nesting and breeding

Builds a small moss nest on a bare rock ledge in a location kept constantly damp by spray, typically behind or beside a waterfall or in a sea cave. A single egg is laid and incubated for roughly 3-4 weeks, one of the longest incubation periods relative to body size of any North American bird.