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Black Swift

By Ben Young

A“Enigmatic.” “Unknown.” Take a glance at the species account for the Black Swift (Cypseloides niger) in your field guide and you’ll see such descriptors associated with aspects of its life history. How else can one describe a non-perching bird that is seen only as it flies (Sibley 2000) (often foraging high enough in the sky to escape detection with binoculars (Rathbun 1925), nests in dark crevices or on ledges near or behind waterfalls that receive little to no direct sunlight, and for which only 124 nest sites have been confirmed worldwide (Levad 2010)? To add to the intrigue, the wintering range for North American breeding birds remains unknown.

The detection of Black Swifts in Montana began in the 1940’s with observations of the birds at Glacier National Park, the Mission Mountains, Coram, Flathead Lake, and the National Bison Range. The species continues to be observed at these locations and more during the summer months, frequently in overcast conditions preceding rainstorms, which tend to bring the birds’ foraging altitude lower, thus allowing for easier detection. Mid-June reports of Black Swift sightings from the Flathead Valley have occurred with regularity in recent years, namely from the north end of Flathead Lake.
Identification of Black Swifts, as with any bird, includes recognizing characteristic body shape, size, and colors, behavior, habitat, and voice. The first clues to identifying a mysterious fly-by bird as a swift are sickle-shaped wings and stiff-winged, somewhat erratic, flight style. Despite superficial resemblance to swallows in their aerial insectivory and general shape, the two groups are not closely related. Rather, taxonomists have classified swifts in the same order as hummingbirds (Apodiformes) primarily as a result of the similarities in wing structure (Sibley 2008).

Once you have identified your mystery bird as a swift, consider the following features to distinguish Black Swift from the common Vaux’s Swift: size (Black Swifts dwarf Vaux’s with a mass (45 g) more than twice that of Vaux’s and a wingspan that is a half-foot longer; color (Black Swifts are much darker); flight style (Black Swifts tend to intersperse quick wingbeats with periods of gliding that are more pronounced than Vaux’s); tail (Black Swift males show distinct notched tail, unlike Vaux’s); voice (Black Swift gives bursts of low chirping or clicking notes that bear resemblance to Red Crossbills, compared to the sharp chips and buzzy trills of the Vaux’s) (Alderfer 2006).

Despite their annual occurrence in the region and the relative ease in identifying Black Swifts, finding nest sites has proved a daunting challenge since the discovery of the species in 1857 in coastal Washington. The rarity of known Black Swift nests was such that toward the end of the 60-yr period of intense egg-collecting in the U.S., the price of a single Black Swift egg in 1922, $75, according to The American Oologist’s Exchange Price List of North American Bird’s Eggs, was eclipsed only by the California Condor ($750), Ivory-billed Woodpecker ($100), and Passenger Pigeon ($100) (Levad 2010). In fact, the first documented discovery of nesting birds in Montana did not occur until 1961, when high school science teacher William F. Hunter, working at the Montana State University Biological Station under his advising professor of ornithology, Paul H. Baldwin, published their findings of the state’s first confirmed colony of Black Swifts, found in the Mission Mountains outside of St. Ignatius (Hunter and Baldwin 1962).

Subsequent searches for nests by Hunter and Baldwin in the summer of 1962 revealed active Black Swift nests in Glacier National Park (Hunter and Baldwin 1972). Organized Black Swift nest surveys in Montana did not occur again until 2004, when Dan Casey, Northern Rocky Mountain Bird Conservation Region Coordinator, spearheaded a team of researchers in resurrecting Hunter and Baldwin’s nest-locating efforts. The team prospected 32 sites in northwest Montana that exhibited the five key physical requirements of Black Swift nest sites (Knorr 1961): (1) water; (2) high relief; (3) inaccessibility to terrestrial predators; (4) shaded; (5) unobstructed approach. Their explorations yielded one new nest site on Haystack Creek, visible from Going-to-the-Sun Road.

Given the relatively scant information on the breeding and nonbreeding locations, as well as population trends of these birds, the status of the Black Swift remains uncertain (S. Gniadek, personal communication, August 15, 2011). Recent declines in its British Columbia breeding range have led to its classification as a species of concern on the U.S. WatchList of Birds. Longitudinal monitoring of established nesting sites may further elucidate how Black Swift populations are responding to various environmental stressors. Of particular significance to the birds nesting in our region is the potential for reduced stream flows that climate change models predict for the long-term. As studies continue to reveal the melting of glaciers in Glacier National Park (Hall and Fagre 2003), concern exists over the subsequent impacts of the net loss of waterfalls on Black Swift nesting habitat.

One of the most perplexing matters in the life history of the Black Swift is its whereabouts in the winter. Work by Rocky Mountain Bird Observatory, U.S. Forest Service, and Colorado Division of Wildlife personnel over the past two years may soon solve this mystery. In the summer of 2009 in Colorado, four Black Swifts were captured and outfitted with geolocator devices used to track movements. Last summer, three of the four birds were recaptured, and geolocators were obtained. As researchers interpret the data from these devices, there is much anticipation for the revelation of this great mystery of North American bird migration. Stay tuned.

REFERENCES:
Alderfer, J. 2006. National Geographic: Complete Birds of North America. Washington D.C.: National Geographic, pp. 342-343.
Hunter, J. E. and P. H. Baldwin. 1962. Nesting of the Black Swift in Montana. Wilson Bulletin 74:409-416.
Hunter, J. E. and P. H. Baldwin. 1972. Black Swift nest in Glacier National Park. Murrelet 53:50-51.
Hall, M. H. P. and D. B. Fagre. 2003. Modeled Climate-Induced Glacier Change in Glacier National Park, 1850-2100. Bioscience 53:131-140.
Knorr, O. A. 1961. The geographical and ecological distribution of the Black Swift in Colorado. Wilson Bulletin 73:155-170.
Levad, R. 2010. The Coolest Bird: A Natural History of the Black Swift and Those Who Have Pursued It. American Birding Association: http://www.aba.org/thecoolestbird.pdf.
Rathbun, S. F. 1925. The Black Swift and its habits. Auk 42:497-516.
Sibley, D. A. 2000. The Sibley Guide to Birds. New York: Alfred A. Knopf, p. 291.
Sibley, D. A. 2008. The Sibley Guide to Bird Life & Behavior. New York: Alfred A Knopf, pp. 353-356.

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