With fewer cars on the road because of the pandemic, birds no longer have to shout to be heard. The result? Softer, sweeter songs, say researchers in a new study at Science. More to the point, "sexier" songs, lead researcher Elizabeth Derryberry of the University of Tennessee tells AFP. "When you're shouting at a cocktail party, your voice is not at its best," she says, adding that the same applies to birds. She and her team compared the songs of white-crowned sparrows around San Francisco before and after the coronavirus lockdown led to a dramatic reduction in road traffic, per Courthouse News. They discovered that as noise pollution dropped, male sparrows adjusted their songs to be quieter, but with a wider range of notes. In short, they made better music to woo females.
"Although noise recordings are not available from the 1950s, this benchmark indicates that a relatively brief but dramatic change in human behavior effectively erased more than a half-century of urban noise pollution and concomitant soundscape divergence between urban and nearby rural areas," the study says. The researchers estimate that the spring lockdown reduced noise by 50%, with the number of vehicles traversing the Golden Gate Bridge dropping to levels last seen in 1954. The birds quickly took advantage. Their ability to adapt suggests the males will go back to shouting if and when the human world returns to normal. (A more troubling story about migratory birds is unfolding in the West.)