Foraging site fidelity in fur seal females

 Subantarctic fur seal mother and pup. Photo: Nico de Bruyn

Subantarctic fur seal mother and pup. Photo: Nico de Bruyn

Subantarctic fur seal adult females from Marion Island travel thousands of kilometres across the Southern Ocean when searching for prey. They return to the island to nurse their pups and this provides an excellent ‘research platform’ for assessing conditions and potential environmental changes in distant parts of the Southern Ocean. For several years, we have been attaching satellite tracking devices to lactating fur seal mothers to ascertain their foraging movements. In so doing we tried to unravel the question of fidelity to foraging areas. We were interested in whether these fur seal mothers visited the same foraging grounds over different seasons and/or between different years. Such information provides us with an idea of changes in the environment over time and how these might relate to the population dynamics of the fur seals.

Just like humans often prefer different types of food (and thus restaurants) in summer as opposed to winter, so too did the fur seal females. There was little overlap in where they went to forage over the different seasons in a year. However, in the same seasons across different years they showed a remarkable conformity in travel direction away from Marion Island with substantial overlap in foraging areas considering that they track highly mobile prey!  Read more here (click on text).