Abstract
The relationship between individual variation in foraging trip duration in Japanese Cormorants Phalacrocorax filamentosus and their ability to feed their chicks was examined. The dietary mass of different prey types (epipelagic or epi- and benthic fish) was estimated and compared, and the nest attendance patterns and breeding performance of adult birds were observed. There was no difference in dietary mass of each prey type. The duration of foraging trips varied significantly among individuals, and individuals that conducted repeated short trips had higher provisioning rates than individuals that conducted longer trips. Chicks that received high provisioning rates had a higher proportion fledged. These results suggest that variation in foraging trip duration affects breeding success.
