Regional variation in the impacts of the COVID-19 pandemic on data collection


Study finds when human behavior changes, so do the data


Credit: Susan Spear, Cornell Lab of Ornithology

Ithaca, NY–The COVID-19 pandemic has changed life as we know it all around the world. It’s changed human behavior, and that has major consequences for data-gathering citizen-science projects such as eBird, run by the Cornell Lab of Ornithology. This worldwide database now contains more than a billion observations and is a mainstay of many scientific studies of bird populations. Newly published research in the journal Biological Conservation finds that when human behaviors change, so do the data.

“We examined eBird data submitted during April 2020 and compared them to data from April of prior years,” explains lead author Wesley Hochachka, a researcher at the Cornell Lab. “The outbreak of COVID-19 followed by stay-at-home orders have definitely affected the quantity and quality of data collected by participants. We concluded that any future analyses of eBird data from the pandemic period will have to take into account the region-specific impact on the data collection process.”

Researchers focused on eBird reports from New York State, California, Spain, and Portugal. One of the biggest changes they noted was in the type of habitat the reports were coming from. With more people at home, there were more reports clustered in urban areas. With urbanized areas represented more frequently, birds species that live near humans may also be disproportionately represented. Less common habitats, such as wetlands, may then be under-sampled because restrictions on human travel make it less likely that birdwatchers will go there.

“We also found subtler changes in quantity of data collected, as well as in the amount of time spent birdwatching,” Hochachka says. “That has an impact on how we will need to analyze these data in order to be confident in our findings.. The other crucial point is that changes in human behavior differed in each region, depending upon political and policy responses to the pandemic as well as the different environments in which eBird participants live.”

Though the focus was on four specific regions, the researchers expect that similar changes in the data have occurred on a global scale. The impact could be especially great for programs using eBird data to monitor for changes in distribution and abundance of bird species, such as looking for the impacts of COVID-19 on the bird species themselves.

“Our results indicate that it is impossible to create a universal prescription for dealing with the impacts of the changed behavior of birdwatchers,” Hochachka says. “Instead, any use of the data from 2020 will require analysts to determine how the COVID-19 pandemic has affected their data and apply the necessary corrections.”



Wesley M. Hochachka, Hany Alonso, Carlos Gutiérrez-Expósito, Eliot Miller, Alison Johnston,

Regional variation in the impacts of the COVID-19 pandemic on the quantity and quality of data collected by the project eBird, Biological Conservation, 2021.

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