Monogamy in Leach's Storm-Petrel: DNA-fingerprinting evidence

We used multilocus minisatellite DNA fingerprinting to estimate the frequency of extrapair fertilizations in a population of Leach's Storm-Petrel (Oceanodroma leucorhoa) on Kent Island, New Brunswick, Canada. Leach's Storm-Petrel is a member of Procellariiformes, an order of long-lived pelagic birds characterized by long-term pairbonds, single-egg clutches, and extended periods of parental care. We found no evidence of extrapair fertilizations in 48 families (42 full families and 6 partial families consisting of the putative father and the single offspring). Thus, our results indicate that the breeding system (genetic monogamy) matches the mating system (social monogamy) in our study population, a condition that no longer can be assumed in socially monogamous bird species. Genetic monogamy in Leach's Storm-Petrels may be maintained by last-sperm precedence and frequent copulation by mates during the female's fertile period. Such tactics employed by a male may yield a high probability of fertilizing the single egg laid by his mate.