Foraging specificity and prey utilization: evaluating social and memory-based strategies in seabirds

Abstract

This study explores the capacity for seabirds to exhibit behavioral plasticity in response to the predictability of resources. Using direct species-comparisons, I tested the hypothesis that roseate terns (Sterna dougallii), dietary specialists, rely more heavily on foraging site-fidelity to pursue persistent prey, whereas common terns (S. hirundo), prey generalists, depend more on local enhancement by exploiting mixed-species assemblages. I analysed chick-provisioning observations and the bearings of commuting trajectories between the shared breeding colony, foraging areas, and feeding flocks. Foraging route patterns in roseate terns were consistent with a strategy based more heavily on spatial memory than social cues, in contrast to common terns, which associated more readily with nearby feeding aggregations, in line with social facilitation. Only during years of high prey abundance did roseate terns outperform common terns in nest productivity and the quality of prey delivered to chicks, suggesting that opportunistic tactics support resilience to sparse prey availability.