Survival costs of reproduction are independent of energy costs in a seabird, the pelagic cormorant

Abstract

Life-history theory predicts that investment in reproduction should decrease survival (the ‘cost of reproduction’). It is often assumed that energy allocation drives such trade-offs, with limited energy available for both reproduction and survival. However, the underlying mechanisms remain poorly understood, maybe because survival costs of reproduction are only apparent when resources are limited. Here, we took advantage of a natural experiment created by fluctuating environmental conditions to compare energy expenditure of a seabird, the pelagic cormorant (Phalacrocorax pelagicus), between contrasting population-scale scenarios of survival costs of reproduction. We used multi-state capture–recapture modelling across 16 years to identify which breeding seasons induced high survival costs (survival ratebreeders