When the Covid-19 pandemic lockdown forced swathes of humanity back into their houses, the silence that swept across towns and cities was such that it got its own name. The “anthropause” saw a plummet in human behavior, some of the consequences of which included an increase in wildlife sightings and a reduction in harmful pollution such as carbon dioxide emissions (sadly, not long term). Another type of pollution that was curbed was sound, and new research published in the journal Science has revealed the surprising effect this had on San Francisco’s sparrows.
Imagine you’re at a crowded bar at the back of a noisy gig (remember those?). When you try to order a drink your speech is loud, strained and a little grating on the ears – not exactly your most flattering tone of voice. For white-crowned sparrows in San Francisco, this is a bit what it feels like for males attempting to lure in a lady with their soulful singing over the calamitous backdrop of traffic.
According to this new research, when a statewide lockdown kicked off in spring, the number of vehicles crossing the Golden Gate Bridge fell to their lowest since 1954 and noise pollution dipped by 50 percent. The team decided to look at how this reduction in manmade racket was affecting birdsong and compared recordings made in April and May of this year to the last few years. Their findings revealed that with a quieter performance arena, the sparrows were singing more softly and hitting much lower notes, making their songs more appealing to the opposite sex.
So how does a fresh composition translate in terms of the sparrow's chances of finding a mate?
"These birds use their songs to defend breeding territories and attract mates, therefore any change in their mating signal (songs) will likely affect reproductive success," lead researcher Elizabeth Derryberry, a behavioral ecologist at the University of Tennessee, told IFLScience.
While it's possible the males enjoyed a profitable spring as a result of their freshly mixed songs, Derryberry suspects they'll be forced to switch back to the classics next year when sound pollution returns. "I think their songs will change again next spring. It is possible that their songs will shift back to the way they were before the pandemic or that it might take a few years. We will be in the field in the spring to find this out!"
The research joins mounting evidence as to how the various lockdowns that took place globally this year influenced the behavior of local wildlife and demonstrate how even a short reduction in human activity can spell big changes for animals attempting to thrive in urban environments.