Links between personality, reproductive success and re-pairing patterns in a long-lived seabird

In long-lived monogamous species, the trigger of costly re-pairing is not always clear. Limited research suggests that within-pair behavioural compatibility may be an important driver of partnership success, as cooperation should be enhanced when pair members' decisions complement one another. Animals' decision-making processes are influenced by personality traits – defined as individual differences in behaviour that are stable in time. Despite the potential for the personality trait ‘boldness’ to (a) directly impact individual willingness to re-pair and (b) indirectly impact re-pairing choices via reproductive success, there is currently little work exploring how re-pairing decisions might be impacted by the pair members' personalities. Using a 13-year dataset, we investigated whether within-pair boldness and its relationship with breeding success explained re-pairing patterns of black-legged kittiwakes (Rissa tridactyla), breeding in two Arctic colonies. We found that pairs with dissimilar boldness levels were more likely to experience breeding failure and that failed pairs were more likely to re-pair the following year. Despite this, only one colony displayed evidence of assortative mating by boldness, and there was no indication that re-pairing impacted reproductive success the following season. Neither individual nor pair boldness directly influenced re-pairing probability; however, in both colonies, re-pairing birds chose partners that were slightly more similar to themselves in boldness than their previous mates. These results imply an indirect pathway by which poorer behavioural compatibility within pairs may lead to breeding failure and ultimately re-pairing. Our findings highlight the importance of behavioural compatibility, and possibly personality, in mitigating sexual conflict and its population-specific drivers.