Birds gotta fly, and for that they have wings. But nature is a tinkerer, adding new functions to old adaptations, and so it can be with feathers.
Males of some birds make sounds during aerial courtship displays, sounds that do not originate in their throats. When these suitors periodically dive during flight, their modified wing or tail feathers vibrate like the reed of a saxophone, creating a hum that appeals to potential mates. In an earlier program, you heard the winnowing sounds of diving male snipe, and if you have a hummingbird feeder at home, you have been hearing a wing trill from insistent male broad-tailed hummingbirds as they display for prospective mates.
Today’s featured bird calls as it flies high overhead on our warm summer evenings.
Those piercing nasal cries are made by Common Nighthawks as they sail effortlessly through the evening air on streamlined wings, their short wide bills agape to intercept flying insects. Periodically, this peaceful scene is disrupted by an unexpected booming sound.
That was no bullfrog croaking, but the male nighthawk generating feather sounds during a brief nosedive. Their booming display is easily missed, leaving you to puzzle as to the source of such an odd outburst. It lends the nighthawk its other common name, the bullbat, like a bat in flight that sounds like a distant bellowing bull. No other Utah bird makes this sound. So as a fiery summer sunset unfolds, look for nighthawks peacefully plying the sky, and listen for their distinctive booming. We have waited all winter for such lovely moments.
This is Linda Kervin for Bridgerland Audubon Society.
Audio: Kevin Colver, 7loons.com
Photos: Courtesy US FWS Digital Library, Thomas G. Barnes Photographer
Text: Jim Cane, Bridgerland Audubon Society
Common Nighthawk, Utah Conservation Data Center, Utah Division of Wildlife Resources, http://dwrcdc.nr.utah.gov/rsgis2/Search/Display.asp?FlNm=chormino
Common Nighthawk, All About Birds, The Cornell Lab of Ornithology, http://www.allaboutbirds.org/guide/Common_Nighthawk/lifehistory