Warblers, hummingbirds, hawks and other migratory birds across Canada and the United States have been hanging out in cities during the spring 2020 pandemic closures, treating urban humans to many more visits than usual, according to a new study.
Bird watching is a hobby that gained popularity during the COVID-19 pandemic. And many birders have recorded the species they have seen and their locations, through “citizen science” applications such as eBird that allow data collected by volunteers to be used by scientists for research on the sea. conservation.
The new study by Canadian and American researchers compared birdwatchers’ observations on eBird between March and May in the three years leading up to the pandemic to those same months during the 2020 closures, which coincided with the spring bird migration. It was funded by a grant from the Natural Sciences and Engineering Research Council of Canada targeting research related to the pandemic.
Where the birds have gone
The researchers found big changes in the study bird species that were spotted. Of the 82 species recorded in the study, 66 of them have changed in abundance in counties where the level of trafficking or human activity has changed. Most species have increased in urban habitats, near major roads and airports and where there were stronger blockages, according to the study.
“We also see with many species in the cities themselves, that they have moved from areas away from roads to areas closer to roads, for example,” said Nicola Koper, professor of conservation biology at the Natural Resources Institute at the University of Manitoba in Winnipeg. . She is the lead author of the study, which also included researchers from Environment and Climate Change Canada, the Cornell Lab of Ornithology, Carleton University in Ottawa, and Dalhousie University in Halifax.
“This suggests that before the pandemic many birds were really being driven from habitats that otherwise might have been suitable for them,” she said, if it hadn’t been for the car traffic and the noise and the collisions. fatal consequences. this.
Bald eagles were one species that made very notable moves to the counties with the biggest drops in traffic, Koper said. “They migrated there using a different model to take advantage of the stronger blockages.”
Sightings of ruby-throated hummingbirds increased dramatically near airports in the spring of 2020.
Another group that appeared to be flocking to urban areas during the closures were the warblers, who have seen very significant population declines since 1970. Koper said she spotted a pollen warbler in her garden – a species she had never seen before.
How to help birds after the pandemic
To Koper’s surprise, even common species such as American robins have spread to areas where they did not previously live.
“Even the birds that surround us in cities are actually much more susceptible to human activity than we might think,” she said. “So that means it is all the more important that we try to reduce our impact on the species with which we share the world.”
Although the study showed that there were more birds in urban areas as a result of the pandemic, it did not measure changes in their actual populations /
But Koper said having access to more habitat and resources during migration, which is a dangerous time for birds, has likely had a positive impact.
She suggested that maintaining certain lockout habits – like working more from home and driving and flying less – could reduce car and air traffic and benefit both birds and humans.
“I think during the pandemic we realized how much we depend… in terms of mental health on nature and green spaces and the birds and wildlife around us, just to make sure we have good quality. of life.”
How pandemic data posed a challenge
Before the pandemic, one of Koper’s research was the impact of oil and gas infrastructure on birds. One of the challenges was to distinguish the impact of the roads themselves on birds from that of traffic.
As she drove out at the start of the pandemic, she says she was struck by the silence and realized that this was an opportunity to examine the impact of the traffic itself on the birds.
While most of his previous work has been direct bird watching in the field, blockages made that impossible this time around. So she turned to eBird data, to which she had volunteered “for fun” for years.
One of the challenges was that birding habits also changed during closures – they tended to watch birds more from their backyards or balconies in town than before, and there were plenty of new ones. bird watchers.
Researchers like Wesley Hochachka, senior research associate at the Cornell Lab of Ornithology in Ithaca, NY, had already warned other scientists on how this changed the nature of eBird data compared to data from previous years.
Koper and colleagues, including Hochachka Cornell’s colleague Alison Johnston, did their best to explain and correct this by comparing the same locations before and during the pandemic and excluding records from new bird watchers who did not. used eBird before the pandemic.
Hochachka, who is Canadian but was not involved in the new study, said that in many cases it was done reasonably or very well, and he agrees that some species appear to have increased in urban areas.
But he believes that with other species, it is possible that they simply changed their behavior, for example by singing more or hiding less, “so that they became more visible or more audible to human observers.” .
While scientists had previously documented how the pandemic has affected individual species in some regions, such as white crowned sparrows and northern cardinals, Hochachka said the new study, including 86 species across North America, shows just how far-reaching the human impacts are.
He said more research is needed to truly answer – and therefore find the solution – to the key question that emerges: “What, in human behavior, might make urban areas unsuitable for at least some?” bird species ? “