Terrestrial and marine risks for leach's storm-petrels during the breeding season

Globally, seabirds are in decline, so comprehensive efforts are needed to understand risks facing these species. Leach’s Storm-Petrels are globally identified as ‘Threatened’, and my thesis addresses two factors which pose risk during the breeding season for the population breeding at Gull Island, Newfoundland: predation and light attraction. Chapter 2 investigates activity associations between breeding storm-petrels and nearby predatory Herring Gulls to gauge predation risk. Herring Gull activity was negatively associated with, and was the most important predictor of, Leach’s Storm-Petrel activity, suggesting that storm-petrels modify their colony activity in response to their top predator. Chapter 3 examines foraging tracks of parental storm-petrels to assess risk from light attraction to offshore oil platforms. This population of storm-petrels was consistent in foraging trip duration, distance, behaviour, and location. They transited past oil platforms during the day, thereby minimising risk. Breeding season risks from predation and light attraction are minimised by existing constraints on behaviour, so future research should focus on other risks to adults along with the juvenile and immature phases of the life cycle. Overall, I demonstrate that a comprehensive examination of risks facing seabirds throughout their life cycle is vital for informing effective mitigation efforts