Consistent among-individual variations in nest defence behaviour in a colonial seabird are associated with nesting site selection

Behavioural responses are among the fastest ways for wild animals to respond and adapt to environmental change. In breeding birds, nest defence behaviour is particularly important, as it directly influences reproductive success. However, the flexibility of this behaviour, and its links to environmental conditions and fitness, remain poorly understood. Here, we investigate the repeatability of flight initiation distance (FID) – a proxy for nest defence behaviour – in Common gull ( Larus canus ) breeding pairs within a seabird colony. We assess how consistent individual differences in FID relate to nesting site selection and fitness-related traits. We find that FID is strongly repeatable at the nest level (R = 0.50), indicating consistent behavioural differences among breeding pairs. Moreover, “bolder” pairs tend to nest at greater heights and in areas with higher conspecific density compared to “shier” pairs. Finally, our results suggest that different behavioural types may achieve similar fitness outcomes by selecting nesting sites that match their behavioural types.