Sparrows sing 'sexier,' more complex mating songs during lockdown: study
With less human noise to compete with, the birds are able to have 'deeper conversations,' says biologist
Male sparrows have really improved their pick-up lines during the pandemic, a new study has found.
Researchers studying birdsong in the San Francisco Bay found the sparrows' mating calls became quieter, more complex, and just generally "sexier" now that they don't have to compete with the sounds of cars and cellphones, says study co-author Elizabeth Derryberry.
"It's kind of like going to a cocktail party where, as people arrive and it gets louder, you also get louder and you probably stop talking about philosophy, and you have more small talk," Derryberry, a University of Tennessee behavioural ecologist, told As It Happens host Carol Off.
"As the party winds down and people go home, you get quieter again, right? You don't keep yelling, and you maybe have your sort of deeper conversations at that point. Well, it's the same thing for the birds."
The study was published Thursday in the journal Science.
Before Derryberry and her colleagues started their research, she'd been hearing a lot of anecdotal reports that birds were singing more during the lockdown, and that it sounded different than before.
"It took a visual to make me suspect it. I was on social media and I saw a picture of the Golden Gate Bridge with coyotes crossing, and I was shocked. There was no traffic and it made me realize it must be really quiet," she said.
Fortunately, there was already data to work with thanks to a long-standing study of the birdsong of white-crowned sparrows in the area.
The researchers compared the songs recorded before COVID-19 restrictions were enacted, to those that came during the lockdown measures.
"We suspected that we would hear them change their song in some ways, that they would get a little quieter as the noise levels dropped," she said. "But we didn't quite expect this degree of change."
The birds may sound louder, but in fact, they're much quieter, Derryberry said.
We're just hearing them more clearly because they're able to transmit their mating calls at twice the distance, she explained. The recordings also picked up females cooing back approvingly to the males, filling the area with a lovely melody.
"That communication distance is doubled, which is great for the birds and, I think, great for us too," she said.
The songs are also more complex, she said, meaning they're transmitting more information.
"They are communicating that the territory is theirs. I like to say they're singing, 'This is mine, mine, mine.' And they're also trying to attract females," Derryberry said.
"So the function hasn't changed, but they've got much better at signaling it."
The findings, she said, can easily be placed into context with reports of animals reclaiming human territory all over the world at the height of lockdown measures — wild boar on the streets of Israel, for example, or mountain goats making themselves at home in a Welsh village.
"With movement, we see humans move out of the landscape and animals move in. And here with sound, we're seeing that when humans move out of the soundscape, the birds are moving in," Derryberry said.
So what happens when the humans come back?
In the Straits of Gibraltar, pods of orcas have been ramming into boats in recent months since the shipping lanes started filling back up with traffic. One marine biologist told the Guardian they may be angry because noise levels have cranked back up after a period of calm.
"I don't think we're going to have a situation like Hitchcock's The Birds here," Derryberry said. "But I do think that their songs will change, and we'll be out there next year recording to see."
Written by Sheena Goodyear. Interview produced by Sarah Cooper.