365 Urban Species. #164: Chimney Swift
Location: over the Riverway, by Simmons College.
Urban species #164: Chimney swift Chaetura pelagica
Above is the best view most city dwellers will get of a chimney swift: always in flight, almost always twittering. This bird is easy to recognize at a distance, which is fortunate, because it is always at a distance. The "tail-less" appearance is distinctive, as is the lack of perching behavior. It almost never stops flying, and when it does, it does so well out of sight, preferring to nest in unused chimneys and smokestacks. Before these man-made nest sites existed, they used hollow trees, but once the first colonists built chimneys, the swifts moved in and multiplied. Like the case of the cellar spider, the creation of man-made habitat created a population increase among chimney swifts.
We should be happy that there are more chimney swifts than there once were, as these birds feed exclusively on flying insects, including mosquitoes. Like their closest relatives, the hummingbirds, they must eat a tremendous amount, up to a third of their body weight per day. Because there are fewer smokestacks and fewer fireplaces in modern cities, the swift's numbers are declining. On the west coast the chimney swift is replaced with Vaux's swift (Chaetura vauxi) and in European cities by the European swift (Apus apus).