Birds went quiet as wildfire smoke blanketed NYS, study finds

One early morning in June 2023, Trifosa Simamora was walking in the Finger Lakes National Forest, heading out to change the batteries and memory cards in the acoustic monitors she’d set up to record birdsong.

Wildfires were burning out of control in the forests of Quebec that day, sending smoke across Long Island and the northeast. The sky was dark gray and hazy, the sun was tinted orange, and the air smelled like a bonfire, Simamora, a PhD candidate at Cornell University, recalls.

It was also very quiet. Simamora and her research partner, Timothy Boycott, noticed they weren't hearing the familiar calls of meadowlarks, bobolinks and savannah sparrows, and they thought the fires might be the reason. 

They set out to test their hunch, and their conclusion, published last month in the journal Biological Conservation, was that the birds in their test sites went quiet as the smoke drifted in from hundreds of miles to the north — in the middle of breeding season when they most needed to make themselves heard.

Simamora and Boycott collected data from air quality monitors during two periods of heavy smoke, in June and July 2023, and also gathered recordings of birdsong from the same days at 45 sites in western and upstate New York. They focused on eight species, some of which live only in grasslands, such as the bobolink, savannah sparrow, and Eastern meadowlark.

Most of birdsong recording were collected from agriculture fields growing alfalfa, corn and hay, as native grassland habitat is rare in New York. About 24 fragmented acres remain of Hempstead Plains, a prairie that once rolled across Long Island from Queens to Farmingdale. That remnant harbors 99 native bird species, according to Shana Caro, a biologist at Adelphi University, including some of the species in Simamora and Boycott's study. 

When the researchers matched their recordings to the air quality data, they found that, overall, birds sang the least on the smokiest days.

Usually in the morning, especially during breeding and nesting season, male birds in particular are very vocal — singing to attract mates, singing to alert other males that they’ve claimed their territory. But the fires had silenced the birds at the time they most needed to make themselves heard.

Grassland birds are already "among the most vulnerable in North America," according to a 2019 report from the National Audubon Society. Their populations have declined more than 40% in the past half century, largely because of habitat loss. 

At the same time, forest fires have grown larger and more intense, and large fires have burned in areas that once were relatively untouched — like the Quebec fires of 2023 that darkened the skies across New York.

As the skies turned yellow, public health experts advised people to stay indoors. "It's also going to be unsafe for the birds to be outside," Caro said in an interview. "But they don't have anywhere they can go."

Caro, who is studying with her colleague Kaiya Provost how human activities affect birdsong, said wildfire smoke can irritate birds’ vocal tracts, just as they do humans’. The dark skies and redder light interferes with their circadian rhythms, which cue their morning songs. Both could account for songless summer mornings.

"This is another potential stressor on these already imperiled birds," Boycott told Newsday. If those stresses coincide with peak breeding and nesting periods, the authors warned, it could damage their health and reproductive success. 

Their study offers further reason to protect these species and their habits, he said. "We really need to double down on the efforts we do have."