the aim of this work was to study foraging trip duration and body size of male and female magellanic penguins during the breeding season and to determine the association of these parameters with both reproductive success and clutch quality in a colony located in the beagle channel, tierra del fuego. trip duration differed significantly between sexes and between breeding stages. females performed longer trips than males during incubation. we suggest that this could be due to differences in body reserves and foraging capabilities related with their body condition. in both sexes, foraging trips during incubation were longer than in the other stages, while the shortest trips were observed during early chick rearing. trips were shorter when chicks were smaller and required greater parental care. a high value of reproductive success (1.51 chicks per nest) was recorded in comparison to that observed in colonies from the malvinas islands and punta tombo. these results could be related to differences in food availability in nearby waters. body size of parents was not associated with reproductive success. notwithstanding, larger females produced larger chicks at early moult and clutches of higher quality. the correlation between female body size and chick size at early moult suggests an important contribution of females on chick's development.