Predator-avoidance behaviour in a nocturnal petrel exposed to a novel predator: Predator-avoidance behaviour in a nocturnal petrel

Many species of bird recognize acoustic and visual cues given by their predators andhave complex defence adaptations to reduce predation risk. Recognition of threats posedby specific predators and specialized anti-predation behaviours are common. In this studywe investigated predator recognition and anti-predation behaviours in a pelagic seabird,Leach’s Storm-petrel Oceanodroma leucorhoa, at a site where predation risk from GreatSkuas Stercorarius skua is exceptionally high. Leach’s Storm-petrels breed in burrows andcome on land only at night. Counter-predator adaptations were investigated correlativelyin relation to changing natural light levels at night, and experimentally in relation to noc-turnal visual and acoustic signals from Great Skuas. Colony attendance by Leach’sStorm-petrels was attuned to changes in light conditions at night and was highest whennights were darkest. This behaviour is likely to reduce predation risk on land; however,specific recognition of Great Skuas and specialized defence behaviours were not found.Leach’s Storm-petrels, in particular apparently non-breeding individuals, were entirelynaïve to the threat posed by Great Skuas and were captured easily in a variety of differ-ent ways, on the ground and in the air. Lack of specialized behavioural adaptations inLeach’s Storm-petrels against Great Skuas may be because spatial overlap of breedingdistributions of these species appears to be a rare and recent phenomenon.