Reproductive foraging ecology of five sympatrically breeding alcid seabirds

I used stable isotope methods to track the diets and habitat use of five sympatrically breeding Alcid seabirds throughout three stages of reproduction. Eggs, and nestling tissues were also collected in order to examine differences between items selected for provisioning offspring and those selected for self-feeding. This sampling protocol permitted an experimental field-based validation of isotopic discrimination for whole blood, which revealed that conventional lab-based estimates of this central parameter (∼3.4‰) are >200% higher than the field-based estimates calculated here (∼1.06‰). Using these field-based estimates, I show that the diets and habitat use of these five sympatric Alcids can differ between stages, as well as between adults and offspring. These results have implications for designing marine protected areas, and predicting the effects of climate-change, as well as for considering the evolutionary relationships between foraging and reproduction.