Species Profile: Black Swift

Mystery Bird

The story of the Black Swift has all the components of a good mystery novel. It starts with a character description: a relatively small, sparrow-sized bird, with non-descript black plumage that lives in places that are often remote and inaccessible, that flies like a bullet, often at heights at the edge of our visibility, and that appears infrequently at its nesting site, often just as it is getting dark. Add to that a nesting environment that embodies power and beauty – waterfalls - and an ecology that is more similar to that of seabirds (such as puffins or murrelets) than that of landbirds, and you can see why the Black Swift is one of most unusual, mysterious, and sought after birds in western North America.

Even its breeding distribution is unusual. Black Swifts are known to nest in mountain ranges scattered from southeastern Alaska to western Mexico and Central America, and islands in the West Indies. However, fewer than 200 nesting sites are known and they are apparently absent from large areas.

What We Know

Black Swifts are widely known as the species that nests at waterfalls. In fact, they often place their nest behind the veil of falling water on a moss-covered ledge or crevice in the rock.

Many characteristics of their unique nesting ecology are directly related to the place where they nest. Predation is rare because of the inaccessibility of the nest site, so unlike most small landbirds, there is no urgency in incubation and rearing of the young. Each pair of Black Swifts only lays one egg and they only attempt one brood per year. Their incubation and nesting periods are twice as long as most birds of similar size; 24-28 days for incubation and 40-45 days for the nestling period.

Adults feed young infrequently; up to three to eight hours between feeding bouts for young up to two weeks old, but perhaps only twice per day for an older nestling. Food consists of a "bolus" or conglomeration of insects accumulated by the adult over several hours of foraging, and then regurgitated to the nestling.

Black Swifts have high nest site fidelity. All of the colonies located in Colorado in the 1950s remain active today, and each of the colonies seems to be much the same size as it was then. Nest sites are reused year after year.

What We Don't Know

There is a lot we don't know about Black Swifts - even basic biological knowledge. For example, our knowledge about their non-breeding season behavior and ecology is almost non-existent. The best answer to where do they winter is "somewhere in South America". This is based on a few scattered records during migration that suggest birds move over land and sea from southern Mexico into northern South America. Even during the breeding season, our knowledge of some aspects of their basic ecology is poor. For example, how do young survive in a cool damp site unattended for so long? How far do adults go daily for food? Why are some seemingly suitable areas unoccupied? Do one-year old birds return to nest at the waterfall of their birth or elsewhere?

Conservation Steps

Fortunately, we are beginning to unravel some of the mysteries about this species that will enable us to address its status and conservation. This was kick-started with the development of Partners in Flight Bird Conservation Plans that have identified Black Swift as a priority species for conservation in every western state in which the species resides. The recent development of a protocol for visiting and inventorying waterfalls, and pioneering monitoring efforts in Colorado and California have enhanced our knowledge about the species. Since 1998, the number of known colonies in Colorado has increased from 35 or so, identified primarily by Black Swift pioneer Owen Knorr, to 96. A similar effort in Oregon and Washington in 2003 raised the level from about three known sites to 15.

The success of recent inventories is due primarily to many dedicated and motivated volunteers. Because of its habitat specificity, Black Swift is a species that lends itself very well to a volunteer-based monitoring effort. The efforts of volunteers along with that of USDA Forest Service and other agency partners show promise of moving this bird from the lists of least-known species to those of the best-monitored.