Actions taken against the COVID-19 pandemic have dramatically affected many aspects of human activity, giving us a unique opportunity to study how wildlife responds to the human-induced rapid environmental changes. The wearing of face masks, widely adopted to prevent pathogen transmission, represents a novel element in many parts of the world where wearing a face mask was rare before the COVID-19 outbreak. During September 2020-March 2021, we conducted large-scale multi-species field experiments to evaluate whether face mask-use in public places elicits a behavioural response in birds by comparing their escape and alert responses when approached by a researcher with or without a face mask in four European countries (Czech Republic, Finland, Hungary, and Poland) and Israel. We also tested whether these patterns differed between urban and rural sites. We employed Bayesian generalized linear mixed models (with phylogeny and site as random factors) controlling for a suite of covariates and found no association between the face mask-wear and flight initiation distance, alert distance, and fly-away distance, respectively, neither in urban nor in rural birds. However, we found that all three distances were strongly and consistently associated with habitat type and starting distance, with birds showing earlier escape and alert behaviour and longer distances fled when approached in rural than in urban habitats and from longer initial distances. Our results indicate that wearing face masks did not trigger observable changes in antipredator behaviour across the Western Palearctic birds, and our data did not support the role of habituation in explaining this pattern.

Arctic Centre University of Lapland PO Box 122 96101 Rovaniemi Finland

Behavioural Ecology Group Department of Systematic Zoology and Ecology ELTE Eötvös Loránd University Pázmány Péter sétány 1 C 1117 Budapest Hungary; Department of Plant Pathology Institute of Plant Protection Hungarian University of Agriculture and Life Sciences Ménesi út 44 1118 Budapest Hungary

Ben Gurion University of the Negev Eilat Campus P O Box 272 Eilat 88000 Israel

Department of Ecology Institute of Biology University of Veterinary Medicine Budapest Rottenbiller u 50 Budapest H 1077 Hungary

Ecologie Systématique Evolution Université Paris Sud CNRS AgroParisTech Université Paris Saclay Orsay Cedex F 91405 France; Ministry of Education Key Laboratory for Biodiversity Sciences and Ecological Engineering College of Life Sciences Beijing Normal University Beijing 100875 China

Faculty of Environmental Sciences Czech University of Life Sciences Prague Kamýcká 129 165 00 Praha 6 Czech Republic; Department of Zoology Poznań University of Life Sciences Wojska Polskiego 71C 60 625 Poznań Poland

Faculty of Environmental Sciences Czech University of Life Sciences Prague Kamýcká 129 165 00 Praha 6 Czech Republic; Faculty of Biological Sciences University of Zielona Góra Prof Z Szafrana St 1 PL 65 516 Zielona Góra Poland

Institute of Vertebrate Biology Czech Academy of Sciences Květná 8 603 65 Brno Czech Republic

Institute of Vertebrate Biology Czech Academy of Sciences Květná 8 603 65 Brno Czech Republic; Department of Zoology Faculty of Science Charles University Viničná 7 Praha 12844 Czech Republic

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Urban birds' tolerance towards humans was largely unaffected by COVID-19 shutdown-induced variation in human presence

Bird tolerance to humans in open tropical ecosystems

Face mask-wear did not affect large-scale patterns in escape and alertness of urban and rural birds during the COVID-19 pandemic