Beyond the pair bond: Extra‐pair paternity and quasi‐parasitism in a Blue‐footed Booby colony

We examined the occurrence of extra‐pair paternity (EPP) in a breeding colony of the Blue‐footed Booby Sula nebouxii using genotypic data from 79 families (including 121 chicks). We identified EPP in 11 families (13.9%), with a total of 12 extra‐pair chicks (9.9%); moreover, four chicks (5.06%) from different nests were genetically related only to their putative fathers, suggesting quasi‐parasitism. We evaluated the effect of several ecological and social factors on EPP and found that it occurred throughout the breeding season and across the colony and was only related to hatching order (higher EPP in the first‐hatched chick). When compared with earlier research, the inconsistent patterns among colonies highlight the complexity of the ecological and social interactions underlying mating systems.