Abstract:
To ensure co-existence, sympatric species have to share the resources whether it is habitat, foraging areas or else, food. At Marion Island, four species of penguins breed in sympatry, namely king (Aptenodytes patagonicus., gentoo (Pygoscelis papua., macaroni (Eudyptes chrysolophus. and eastern rockhopper (Eudyptes chrysocome filholi. penguins. These four species have been found to spatially segregate in their foraging habitats. King penguins typically forage offshore, up to 900 km from their breeding colonies, while gentoo penguins remain inshore, reaching no further than 15 km from the shore. In between, the macaroni and rockhopper penguins forage both inshore and offshore depending on life stages. These different behaviours are expected to drive varying degrees of dietary overlap and segregation. Twenty stomach content samples were collected concurrently for the four penguin species on the south-east coast of the island in 2016 and 2017. The stomach contents from the penguins were sorted into their three prey item groups; fish, cephalopod and crustaceans. These groups were then identified to their lowest taxonomic level. Preliminary results show that king and gentoo penguins mainly foraged on fish species with Myctophidae and Nototheniidae remains dominating the king and gentoo stomach content samples, respectively. Macaroni and rockhopper penguins showed a crustacean dominated diet with Euphausiid species representing the bulk of the species in both penguin species. Macaroni penguins consumed quantitatively more fish than rockhopper penguins, as well as a larger size class of the fish prey component. Our study shows how sympatric penguin species at Marion Island ensure co-existence by coupling different foraging areas and dietary segregation. Species preferences in food and foraging areas are likely to be instrumental to explain the population dynamics of the four species at Marion Island in the context of environmental change. - Abstract as displayed in the - Abstract booklet. The presentation on the day may differ from the - Abstract.
