Feeds:
Posts
Comments

Posts Tagged ‘softer songs’

Photo: JN Phillips
A white-crowned sparrow sits near the Golden Gate Bridge in San Francisco. “During lockdown,” writes the Christian Science Monitor, “traffic in the city dwindled to levels not seen since the 1950s.” The lack of noise caused surprising changes.

One thing that’s been interesting in the pandemic has been reading about various wild animals that apparently feel safer exploring suburbs and streets now that they are quieter. Today’s story is about birds that have stopped feeling the need to shout.

Eva Botkin-Kowacki reports at the Christian Science Monitor, “When the pandemic began, Elizabeth Derryberry wasn’t thinking about her research. Her focus was on the basics: how to teach remotely as an associate professor at the University of Tennessee, Knoxville; how to manage the lockdown with her young family; and how to keep everyone safe and healthy.

“But as she scrolled through social media one evening, she saw a picture of a coyote at the empty Golden Gate Bridge in San Francisco. She recalls thinking, ‘Oh my goodness, there really are no cars.’ And as she stared at that image, Dr. Derryberry thought about how quiet it must be nearby without the normal hubbub of traffic – and about the birds she had been studying there.

“Along with her colleague David Luther of George Mason University, Dr. Derryberry had been recording the songs of white-crowned sparrows in both the urban setting of San Francisco and the more rural Marin County to study how the birds responded to the hum of human-made noise. They’d found that the city sparrows sang more loudly, but with a much more limited range, than their country cousins. And the shutdown presented an unprecedented opportunity for the researchers to see if those urban birds changed their tune.

“Indeed, the urban sparrows took full advantage of the relative silence. When the research team recorded birdsongs near the Golden Gate Bridge in April and May of this year, they sounded notably different – and of higher quality – from those recorded during previous springs. Their findings were published [in September] in the journal Science. …

“As people stayed home this spring, many noticed more wildlife around them. Some pondered whether there were actually more birds, for example, or if the quieter cities just made their songs (and presence) more obvious. …

“ ‘When we’re going about our daily lives, we get used to the patterns of the animals that we see,’ says Allison Injaian, a lecturer in the Odum School of Ecology at the University of Georgia, who was not involved in the study. ‘It’s pretty hard to know what we’re missing out on if that never is visible or audible.

“ ‘But when this really unprecedented shift in human behavior occurred,’ she says, it presented ‘a great opportunity for all of us to realize the impact that we ourselves are having on the wildlife around us.’ …

“For the birds themselves, their songs encode information crucial to their existence. White-crowned sparrows, for example, listen to each other’s songs to pick potential mates in spring, and as a way to assess the fitness of another male from afar when deciding whether or not to fight him to try to take over his territory.

“But in cities, they’re typically making a trade-off between the quality of their songs and simply being heard, says Ken Otter, a biologist at University of Northern British Columbia who was not involved in the new study. …

“Before the shutdown, Dr. Derryberry and Dr. Luther found that birds in San Francisco were competing with nearly three times as much noise as those in Marin County. But when the pandemic closed everything down, there was no difference in noise levels. They attribute that to less traffic, as the amount of cars passing through had reverted to levels not seen since the 1950s.

“As a result, birdsongs could travel much farther. The researchers found that the birds sang more softly because they didn’t have to be louder than the anthropogenic noise, and even still, their songs could travel twice the distance as before the shutdown. 

“The bandwidth of the trill at the end of the sparrows’ song is also key to communicating physical fitness to potential mates or rivals. Researchers found previously that the urban birds limit their trills to higher frequencies so they don’t have to compete with the low hum of traffic. But during the shutdown, the team found that the city sparrows utilized their full range – and when they compared the 2020 songs to historical recordings in the area, they found that some of the sparrows were singing in ways not heard in the city since the 1970s. 

“Whether this has a long-term effect remains to be seen, says Dr. Derryberry. But she plans to study the San Francisco sparrows’ sounds during the breeding season once again next year. ‘I’m really excited to see what happened with the nestlings that learned their songs this year,’ she says. …

Birds don’t just adjust their songs’ volume and range. Research has found that some urban birds will adjust the time of day that they sing to avoid rush hour. …

“Studies like this one, Dr. Otter says, can also help give us direction. ‘It’s really important for understanding how we can move forward with planning,’ he says, ‘so that we can create spaces that not only attract the birds, but allow them to be successful.’ ”

More here.

Read Full Post »

%d bloggers like this: