Older gulls adopt more diverse wind drift compensation strategies

Wind drift compensation is crucial for flying birds to reach their destinations efficiently. Although this behaviour is thought to improve with experience, it remains unclear whether wind drift compensation differs among age classes. We investigated wind drift compensation during foraging trips in black‐tailed gulls Larus crassirostris breeding at Kabushima Island, Japan. We used hierarchical Bayesian models to analyse 10 years of GPS tracking data from 95 individuals aged 6–27 years, comprising 1077 trips, and partitioned age‐related patterns in wind drift compensation into population‐level mean, among‐individual variation, and within‐individual variation. Population‐mean drift and among‐individual variation remained stable across ages. In contrast, within‐individual variation showed a clear age‐related pattern, increasing from approximately ages 10–16 and remaining elevated at older ages. This indicates that older birds varied their compensation strategies more across trips rather than improving their average performance. Simulations under a spatially heterogeneous wind field resembling conditions around Kabushima Island showed that optimal routing can generate greater within‐individual variation than perfect compensation, thereby providing a potential explanation for the empirical pattern. Our results suggest that older long‐lived birds may exhibit greater behavioural flexibility across environmental contexts, and highlight the importance of partitioning behavioural variation across multiple levels.