Foraging under changing winds: behavioural responses of the black noddy Anous minutus

Small tropical seabirds operate in unpredictable environments where flexibility is key to survival. Yet, their responses to fine-scale environmental variability remain poorly understood and are likely to differ from those of larger or non-tropical seabirds due to differences in ecology and environmental conditions. Here, we used high-resolution GPS tracking and hidden Markov models to reveal how black noddies Anous minutus breeding on Heron Island, Great Barrier Reef, Australia, adjust their foraging strategies in response to shifting wind conditions, diel cycles, and seasonal changes. Across 4 years (2019-2022), birds showed considerable behavioural plasticity: outbound travel was favoured in light tailwinds, while strong winds triggered direct inbound returns, often into headwinds. High wind speeds suppressed resting activity, promoting persistent travel and foraging-search behaviours, emphasizing the energetic challenges posed by suboptimal wind conditions. Foraging effort peaked in mid-morning, with birds capitalizing on predictable prey availability, while night-time rest was strongly conserved. Notably, inter-annual shifts in movement patterns reflected changing prey landscapes, with increased foraging effort and travel during low-resource years. Despite relying on energetically costly flapping flight, black noddies dynamically modulated their behaviour to navigate fluctuating conditions. Our findings highlight the critical role of behavioural flexibility in enabling small seabirds to cope with environmental uncertainty while raising concerns about their vulnerability to increasing wind variability and changing ocean conditions in a warming climate.