Pandemic-related changes in birding may have consequences for eBird research

By Team eBird February 19, 2021
European Robin Erithacus rubecula

Newly published research in the journal Biological Conservation finds that changes in human behavior during the COVID-19 pandemic can have major consequences for community data-gathering projects such as eBird. Researchers must take into account that when human behaviors change, so do the data being collected.

The study focused on eBird reports from New York State, California, Spain, and Portugal. “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.”

One of the biggest changes they noted was in the type of habitat the reports were coming from. With more people at home, more people reported birds around urban areas. With urbanized areas represented more frequently, bird 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.

Purple Heron © Ivan Sjögren / Macaulay Library

“We also found subtler changes in quantity of data collected, as well as in the amount of time spent birdwatching,” Hochachka says. “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.

This is especially important for programs using eBird data to monitor for changes in distribution and abundance of bird species, including those looking for the impacts of COVID-19 lockdowns on the bird species themselves. The researchers concluded there’s no one-size-fits-all approach for dealing with pandemic-related changes in birding data. “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,” Hochachka says.


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.

Assistance for this article provided by Pat Leonard, Cornell Lab of Ornithology