By Federico Morelli, Yanina Benedetti, Peter Mikula, Daniel T. Blumstein, Mario Díaz, Alicia Page, Piotr Tryjanowski, Marta K. Nowak, and Eva Vincze, Gábor L. Lövei

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Many studies over the past few decades have focused on the escape behaviour of birds, particularly Flight Initiation Distance (FID), in response to potential predators and environmental factors, as well as species-specific characteristics. However, no studies have explored the potential influence of the observer’s sex on the escape behaviour of birds. Given the differences observed in how laboratory animals respond to the sex of human interactants, the absence of such research in the field is surprising.

We surveyed different European cities to collect data on flight initiation distance of birds, to test for the effect of human observer sex on their escape behaviour, after controlling for a variety of other important factors known (e.g., starting distance, flock size, sex of the targeted bird, land use characteristics and vegetation cover). To perform the test, we used statistical models controlling for the phylogenetic relatedness of bird species.

Our findings provide new insights into the role that an observer’s sex plays in affecting the escape behaviour of urban birds. Contrary to our expectations, we discovered that birds tended to flee earlier when approached by women than by men. We proposed several hypotheses to explain this behavioural response. The observed pattern was consistent and clear, even with the extensive dataset collected from numerous European cities included in this study. We conclude that birds can indeed recognize the sex of the humans approaching them. More studies are needed to identify the mechanisms behind the effect of human observer sex on the escape behaviour of urban birds.