Spying on your neighbours? Social information affects timing of breeding and stress hormone levels in a colonial seabird

A good overlap between offspring energetic requirements and availability of resources is required for successful reproduction. Accordingly, individuals from numerous species fine-tune their timing breeding by integrating cues that predict environmental conditions during the period. Besides acquiring information direct interaction with environment (personal information), can integrate observing behaviours or performance others (social information). The use social often beneficial because accumulated knowledge conspecifics may represent a source more reliable than intrinsically limited personal information. However, although constitutes major in wide range contexts, studies investigating its context are scarce. We investigated whether black-legged kittiwakes (Rissa tridactyla) used to adjust egg-laying. manipulated using food-supplementation experiment, known advance kittiwakes' reproductive phenology. expected food-supplemented unsupplemented pairs delay advance, respectively, laying when surrounded majority neighbours opposite food-treatment. both delayed egg-laying higher proportion This result shows time egg-laying, but it not match seasonal peak food availability. suggest give contradictory information, benefit delaying gather make better decisions about investment into eggs. Further, we explored potential proximate mechanism pattern report. show baseline corticosterone, mediate decisions, was lower females facing neighbours. Altogether, our results laying, complex decision-making processes which interplay.