Résumé
Our understanding of demographic processes is mainly based on the analysis of the adult components of populations. However, juvenile survival is decisive for recruitment, and therefore for the dynamics of populations. Our study aims at understanding the environmental determinants of juvenile survival in the emperor penguin, a species for which this critical phase is poorly known. We used capture-mark-recapture models to leverage 13-years of electronic monitoring of birds tagged as fledglings at Pointe Géologie, Adélie Land. Emperor penguin juvenile survival showed very high interannual variability (0.08 to 0.48), a pattern no longer observed in immatures and adults. Furthermore, we emphasized the importance of body mass on juvenile survival, and which was tightly associated with sea ice extent during the chick rearing period. We also showed that oceanographic conditions (width of the polar front) during the first weeks after fledging are an important predictor of juvenile survival. Our results suggest that the conditions of accessibility and abundance of food resources during this phase of learning to swim and dive play a crucial role in the survival of young penguins. Finally, our study provides new insights into sex-specific differences in survival in this species, which seems to emerge only in adulthood.