SF sparrows adapt their song to urban noise
Editor’s: This article is excerpted from the latest issue of Bay Nature magazine. To read the complete article, click here.
By Kim Todd
Lobos Creek trailhead in the Presidio looks wild. Flushed orange monkey flower, sage, and coyote bush spill over re-created sand dunes. Nearby, the creek empties into the ocean. But close your eyes. A water truck pulls up to a stop sign with a mechanical whine. Car engines growl, foghorns moan, a distant airplane whirs. The noise, which never stops even though it’s barely 7 a.m., makes it clear you’re in the middle of the city.
In the parking lot, a white-crowned sparrow perches at the top of an evergreen tree next to a pickup truck and sings, launching a quick patter: whistle, buzz, two-part trill, and a scattering of notes. It’s music familiar to city dwellers, even if they couldn’t name it. The song is key to the white crown’s survival, helping him attract a mate and defend the territory around his nest, warning off other males with his vocal vigor. But the notes are almost drowned out as a bus sighs to a halt. Thanks to recent restoration efforts, the bird is surrounded by plants, such as lupine, that evolved here over centuries, along with the sparrow. But there is no restoring the silence, and the noise grows year by year. What will it take for white crowns like this one to survive in this new soundscape? What will it take to be heard?
Biologists David Luther and Kate Gentry record white-crowned sparrow songs and calls at the Lobos Creek dunes in the Presidio. Photo: Sebastian Kennerknech.
Down the boardwalk, David Luther, a quiet-voiced, rusty-haired biologist from George Mason University in Virginia, is trying to find out.
“In the past ten years or so, there has been mounting evidence of how human noise is affecting these birds,” says Luther. Not just birds, he adds, but other animals, too. Studies in the developing field of “acoustic ecology” show whales, crickets, and frogs altering their behavior in response to man-made sounds. While some flee the cacophony, others adjust their internal clocks. Along a river near the Madrid airport, nightingales and European goldfinches sing earlier in the morning before the roar of the planes starts up. In Sheffield, England, robin redbreasts in noise-cluttered areas have started to sing at night. The whole “dawn chorus” has moved away from dawn.…





