Mate fidelity improves survival and breeding propensity of a long-lived bird

1. Evolutionary and behavioral ecologists have long been interested in factors shaping the variation in mating behavior observed in nature. Whereas, much of the research on this topic has focused on the consequences of mate choice and mate change on annual reproductive success, studies of a potential positive link between mate fidelity and adult demographic rates have been comparatively rare.  This is particularly true for long-lived birds with multi-year, socially monogamous pair bonds. 2. We used a 26-year capture-mark-recapture dataset of 3,330 black brent (Branta bernicla nigricans) to test whether breeding with a familiar mate improved future breeding propensity and survival. We predicted that experienced breeders nesting with a new partner would have rates of survival similar to familiar pairs because long-lived species avoid jeopardizing survival since their lifetime fitness is sensitive to this vital rate. In contrast, we expected that any costs of breeding with a new partn...