My seabird research primarily focuses on wild populations of long-lived birds and their responses to changes in marine ecosystems, including: population responses to historic and recent changes in climate, foraging and diet, using direct methods (diet analyses, radio tracking, data logger technology) as well as non-invasive methods (stable isotope analysis, molecular diet analyses) and speciation. I also studied parent-offspring interactions as honest signalling system, and the regulation of trade-offs in response to variable environmental conditions, using field endocrinology and immunology.