Final Report Summary - CYOV_EFFS (Seasonal interactions in migratory seabirds: influence of carryover effects on fitness) Migratory species spend different stages of the annual cycle in geographically disparate places but events and processes occurring at each stage are inextricably linked because what occurs in one season carries over to influence behaviour, breeding success or survival of the following season. In the present project, we worked on three closely related species of long-lived and long-distance migratory seabirds (Calonectris shearwaters) breeding on Mediterranean and Atlantic Islands. We used the most complete tracking dataset ever compiled, which includes 26 populations (with 11 contributor teams) spread over the breeding range of each species. First, we established the year-round distribution and migratory connectivity and identified the use of specific non-breeding areas, as well as precise migration schedules for the three species. Second, we unravelled how long-distance migrants trade off among energy-demanding activities (mainly breeding, moulting and migrating) by experimentally reducing their parental effort through an induced breeding failure at the incubation stage. We did not detect any difference in the spatio-temporal distribution or the timing of major phenological events between birds put in failure and successful breeders. Nevertheless, failed breeders did advance significantly their moulting schedules (as revealed by stable isotope analysis and flying activity patterns) and showed lower stress levels (inferred through corticosterone concentrations in different feathers), providing robust evidence on how costs of reproduction can be transferred to the next stage but also dilute at the end of it. The complimentary SIA and pollutants of tracked birds allowed us to understand baseline isotopic gradients and pollutant levels in the ocean, with deep ecological, methodological and conservation implications. Our next goals are assessing the impact of carryover effects and the use of different migratory strategies on population dynamics and modelling the environmental preferences of each species to predict and foresee future changes in the habitat utilization of seabirds in relation to global warming. This project has led to a number of scientific achievements (3 published articles in SCI-ranked journals, 4 submitted ms, 7 ms currently in advanced stage of preparation, 2 publications in popular-science journals, 15 oral contributions in 8 international conferences and meetings, etc) that are advancing the fellow’s research career. By participating in the organization of one international conference (IAPC6), supervising 3 PhD (in progress) and 9 Master (7 completed and 2 in progress) students and building a wide international research network (co-authored with >20 research institutes from 10 countries) at the University of Barcelona, the fellow is advancing toward his re-integration at this host institution. Overall, the project significantly contributed to the fellow establishment as mature researcher, opening new research avenues in collaboration with several members of this University.
