My research focuses on ecology, behaviour and conservation of marine predators, with an especial interest in the their ecological roles in the marine ecosystems, their trophic relationships at the food-web level and the main ecological and evolutionary factors, including natural and human-mediated factors, that modulate their behavioural patterns, population dynamics and interspecific interactions. Moreover, a large part of the outputs generated from my work have provided valuable information for ecosystem-based management and the conservation of threatened species. I have conducted my research at different levels of ecological complexity (from species to populations and communities), working with different study models (seabirds, elasmobranchs, fin-fish and cephalopods) in marine ecosystems of contrasting biogeographical areas (template, tropical and polar environments). Additionally, I have also collaborated with colleagues working with similar interests in terrestrial ecosystems, including studies with birds, amphibians and mammals. Among the different methodologies implemented in my research I highlight the use of: stable isotopic values, bio-logging devices, ecophysiological determinations, GIS-procedures, ecosystem modelling and conventional-diet studies.