Temporal and spatial heterogeneity in dispersal and demography of a long‐lived philopatric seabird

Abstract Individuals make habitat selection decisions at different moments of their life and in heterogeneous habitats. Understanding the links between environmental changes and demographic patterns during the individuals' life is therefore critical to predict long‐term eco‐evolutionary dynamics and species persistence. However, fitness and persistence consequences of habitat selection are seldom addressed in demographic studies. We used long‐term capture–recapture data of Mediterranean Storm Petrels to investigate how habitat‐selection decisions are made at different spatial (i.e., among and within breeding zones) and temporal (i.e., natal and breeding fidelity) scales in a colony characterized by significant variation in habitat quality due to contrasting parasite infestation levels. Specifically, we evaluate whether birds hatched in and/or breeding at different zones experience different (1) fitness components (i.e., breeding success and survival) and (2) fidelity (i.e., natal and breeding fidelity). In addition, we (3) explore the causes, environmental cues, and consequences of nest fidelity versus dispersal. Finally, we project (4) how these differences influence population dynamics and persistence (i.e., population growth rate). Our findings reveal that habitat selection decisions have synergistic fitness consequences on multiple temporal and spatial scales considered. Specifically, breeders in the lower quality habitat zone (i.e., high tick infestation) exhibited reduced breeding success, local survival, and nest fidelity, but remained within their zone. Breeding success of individuals exhibiting nest dispersal marginally increased. Moreover, natal fidelity was lowest at the zone where fitness was highest. Overall, population growth rate at the colony suggests an annual population decline between 6% and 10%. Individuals seem to base their dispersal decision, but not their habitat selection choices on public information. As a result, birds do not experience increased fitness, indicating the potential presence of an evolutionary trap. Understanding the interplay between synergistic and opposing habitat choices is central to understanding species eco‐evolutionary dynamics. Further, our results highlight exciting avenues for future research, when aiming to understand the complex and fundamental roles played by heterogeneity in habitat quality in species demography and eco‐evolutionary dynamics, with significant implications for species management and conservation strategies.