Flight Initiation Distance in an Urban Bird: Influence of the Number of People, Gaze Orientation, and Bird Behavior

Background: The flight initiation distance (FID) measures the distance a bird flees from an approaching predator. Factors such as the frequency of predator approaches, the direction of predator gaze, variations in predator presence across different areas, and the specific behaviors displayed by predators can all affect the FID. For birds, people can assume the role of predators. Methods: This study aimed to evaluate whether the FID of the species Sicalis flaveola (Saffron finch, Aves, Passeriformes) is influenced by the number of people and their gaze direction, comparing areas with the greater and lesser flow of people and relating to the types of behavior exhibited by the birds. Results: The results showed that the number of people walking towards the bird influenced the escape behavior, with more people generating longer FIDs than fewer people. If the approach was with the eyes fixed on the birds, the FIDs were longer. When birds were alert, FIDs were longer. Conclusion: Overall, the findings imply that birds exhibit nuanced reactions to human presence, even in areas with frequent human encounters, highlighting their advanced capacity for assessing and responding to perceived risks.