Absence of extra-pair fertilisations in the Chinstrap Penguin Pygoscelis antarctica

We analysed genetic relatedness through DNA-fingerprinting in 38 two-chick families of Chinstrap Penguins Pygoscelis antarctica in the Vapour Col colo ny on Deception Island, Antarctica. Band-sharing coefficients between males and chicks in their nests, females and chicks in their nests and brood mat es were very close to 0.50 and were not significantly different. Presumably unrelated pair mates showed much lower band-sharing coefficients (0.12), w hich differed significantly from those between putative parents and their c hicks and between presumed siblings. No case of extra-pair paternity was de tected according to the presence of novel bands or to band-sharing coeffici ents. Monogamy in the study population is not only social but also genetic.