While the unusual quiet of COVID's first months was hard on many people, it allowed birds in the Pacific Northwest to use a wider range of habitats, according to a newly published University of Washington study.
The study, published Thursday in Scientific Reports, found that in Pacific Northwest cities under lockdown, birds were just as likely to be found in highly developed urban areas as in less-developed green spaces.
"Our findings suggest that some birds may have been able to use more spaces in cities because our human footprint was a little lighter," said Olivia Sanderfoot, who completed the study as a doctoral researcher at the UW School of Environmental and Forest Sciences.
In the spring of 2020, Sanderfoot and colleagues recruited more than 900 community scientists in the Pacific Northwest to monitor sites of their choosing — mostly backyards and parks where they could safely comply with public health orders — and recorded the birds they observed over 10 minutes at least once a week.
Among the 35 species that showed the strongest changes in behavior during COVID lockdowns were some of the region's most iconic, including black-capped chickadees, great blue herons, downy woodpeckers and Wilson's warblers.
Listen to Wilson's warbler (Cardellina pusilla)
The researchers focused on 46 bird species, observed by the study volunteers during more than 6,000 individual surveys.
To compare the volunteers' bird observations to human activity, Sanderfoot and her colleagues used data from Google's Community Mobility Reports, which track the relative amount that people moved around at various points during the pandemic. While most people spent spring 2020 isolated in their homes, many began venturing out again throughout the study period.
Human mobility affected detection of 76% of the species studied, suggesting birds responded to the changes in human activity beginning shortly after initial lockdown restrictions were implemented.
As people returned to public spaces and human activity increased, the volunteers recorded an increase in sightings of birds in more heavily canopied and vegetated areas, such as parks and backyards, suggesting such green spaces are an important refuge for urban birds.
"The birds may have been elsewhere at the height of the lockdowns, because human activity wasn't as much of a disturbance, but then returned to those vegetated areas as the activity increased again," Sanderfoot said in an emailed statement. "This could tell us how important it is to build green spaces into our cities. That's the biggest takeaway for me."
Like countless others who discovered a new interest in birds and bird songs during the early, quiet of the pandemic, the volunteers told researchers the work was a welcome distraction.
"I am loving being a part of this!" said Nadine Santo Pietro, a study volunteer, in a written comment. " ... It's given me something positive to focus on during this strange time we are in right now."
The study was co-authored by Joel Kaufman, a professor in the UW Department of Environmental and Occupational Health Sciences, and Beth Gardner, an associate professor in the UW School of Environmental and Forest Sciences.
The research was funded by the National Science Foundation Graduate Research Fellowship Program and the McIntire-Stennis Cooperative Forestry Research Program from the USDA National Institute of Food and Agriculture.