During the COVID-19 pandemic, lockdowns were accompanied by reports from around the world that wildlife was returning to cities and other populated areas while humans stayed indoors to keep each other safe.
There were also studies on the effects of reduced human activity and noise in wilderness areas like the ocean as shipping and other anthropogenic commotions ceased or were greatly reduced.
Another study, published in the Scientific Reports journal, has found that birds living in and around developed areas in the north-western United States capitalised on the reduction of noise and human bustle to expand their ranges in cities.
Led by University of Washington ecologist Olivia Sanderfoot, the study found that many birds were just as likely to be found in highly developed urban areas as they were in less-developed green areas during the peak of lockdowns.
“Our findings suggest that some birds may have been able to use more spaces in cities because our human footprint was a little lighter,” says Sanderfoot. “For about half of the species we observed, neither land use nor canopy cover had an effect on their site use. That’s very interesting, because we would expect that whether a habitat was mostly covered in concrete or vegetation would tell you something about what birds would be there.”
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The study involved more than 900 citizen scientists in the Pacific Northwest in the spring of 2020. The volunteers monitored sites of their choosing – mostly backyards and parks where they could continue to isolate. They recorded the birds they observed for 10 minutes at least once a week.
Such a community science approach allowed for large volumes of data to be gathered despite the lockdowns. Many volunteers also noted it was a welcome distraction from the stress, fear, isolation, cancelled plans and uncertainty amid the pandemic.
Nadine Santo Pietro, a volunteer, said: “I am loving being a part of this! I signed up to observe once a week for 10 minutes, but it has become so much more than that. I am learning so much! And it’s given me something positive to focus on during this strange time we are in right now.”
Among the 35 species which showed the strongest behavioural changes were some true Pacific Northwest icons like the black-capped chickadees, great blue herons, downy woodpeckers and Wilson’s warblers. Overall, 46 bird species were studied in 6000 individual surveys.
To compare bird activity with human activity, Sanderfoot’s team analysed data from Google’s Community Mobility Reports which track people’s relative movements.
While most spent the spring of 2020 huddled up at home, many began venturing out again over the course of the study. Interestingly, increased human movement actually saw some bird species increase in numbers.
“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. “This could tell us how important it is to build green spaces into our cities. That’s the biggest takeaway for me.”