Foraging parameters of gentoo penguins Pygoscelis papua at Marion Island

Abstract

We measured the foraging parameters of breeding gentoo penguins Pygoscelis papua at sub-Antarctic Marion Island. Mean swimming speed was 7.9 km h-1. Penguins spent on average 8.1 h away from the colony if they returned on the same day they left and 23.7 h away if they remained at sea overnight. Sixteen percent of the total time away at sea was spent swimming. Time spent swimming, and consequently distance travelled, during a foraging trip were highly variable and showed significant intercolony differences. However, 80% of all foraging trips totalled less than 40 km. Meal sizes were small and there was no correlation between meal size and distance travelled, suggesting a low availability of food. Prey items in the diet consisted mainly of the benthic shrimp Nauticaris marionis and the demersal fish Notothenia squamifrons. On evidence from stomach contents and the distances the penguins travelled, we suggest that Nauticaris marionis has a more restricted distribution around Marion Island than does Notothenia squamifrons. The concentration of gentoo penguin breeding colonies along the east coast of Marion Island and the south-east coast of Prince Edward Island may be attributable to favourable feeding conditions between the two islands.