The changes in human mobility in urban landscapes, enforced by restrictions during the COVID-19 pandemic, influenced the so-called urban landscape of fear. This term refers to an environment where animals alter their behaviour in response to human activity. How did the avian inhabitants of cities react to this exceptional situation? An international team led by Peter Mikula and Martin Bulla from the Faculty of Environmental Sciences at the Czech University of Life Sciences Prague studied how the changing number of people outdoors affected the flight initiation distance of birds in cities. The results, indicating significant resilience of birds to the changes, were recently published in the journal Communications Biology.
"The restrictions associated with the COVID-19 pandemic increased the variability in the number of humans in parks, creating unique experimental conditions. We investigated whether birds' tolerance to humans changed and on what time scale, i.e. whether birds responded to hourly, daily, weekly, or annual changes in the number of humans. We also tested whether birds tolerated humans differently in the years before and during the pandemic and whether the level of governmental restrictions affected their tolerance. We measured the degree of avian tolerance as the distance from an approaching human observer at which the bird began to flee. Thanks to the international collaboration, we obtained flight initiation distances for 147 bird species from Prague in Czechia, Rovaniemi in Finland, Poznań in Poland, Budapest in Hungary, and Melbourne in Australia," said Peter Mikula.
The results were surprising. The scientists found no significant differences in birds' tolerance towards humans. Regardless of the number of people in the parks, the flight initiation distances of the birds were similar. "We found only a weak negative relationship with the increasing number of people during an hour or a day. Birds flew away slightly at shorter distance if the number of people increased during an hour or a day. These results suggest that birds are resilient to changes in the number of people in their surroundings. Our study also highlights the complexity of quantifying human movement and animals' response to it," concluded Martin Bulla.
Citation: Mikula, P., Bulla, M., Blumstein, D.T. et al. Urban birds' tolerance towards humans was largely unaffected by COVID-19 shutdown-induced variation in human presence. Commun Biol 7, 874 (2024). https://doi.org/10.1038/s42003-024-06387-z
