Animal-borne sensors for studying foraging and habitat use of marine predators in the Southern Ocean

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Efficient foraging is critical for central place foragers such as seals and seabirds that provision pups/chicks on land via prey caught at sea. In the Southern Ocean, these species rely on energy rich food patches that also attract top-level predators, many of which use sound to communicate and find prey. The acoustic environment, and in particular underwater vocalizations from whales, seals and perhaps even penguins, may provide abundant cues to guide krill eaters in searching for patches while avoiding their predators and competitors. However, little is known about how marine animals harness this sonic information nor is it known whether noise from shipping and industrial activities may disrupt sound-based foraging. This project will use and further develop cutting-edge tag technology to quantify the sounds produced, and the soundscapes experienced, by individual animals along with their fine-scale behaviour over periods of weeks. The miniature tags record the sounds made and heard by animals along with their position (GPS) and fine-scale body movements (accelerometers) over periods of weeks. A high frequency sonar will also be incorporated to assess prey patch density. Tags will be deployed on seals and penguins over multiple foraging trips to study how soundscapes and biotic environment influence searching behaviour, foraging success and therefore offspring growth. This PhD project will require the student to be involved in all aspects of the research including sensor design and calibration, experiment design and field deployments, and data analysis and interpretation. Given the large complex datasets collected, the student will develop computationally efficient analysis tools along with new inferential methods integrating multiple sensor streams. Methods will be developed to describe sound fields, vocalization rates, locomotion effort, and to quantify prey encounter rates and time spent foraging. With this unique combination of data, the student will study how animals locate and exploit ephemeral prey patches and transfer these resources to offspring on land, relating this to descriptors of the soundscapes encountered and observations of pup/chick growth. Methods will be evaluated first on captive animals and potential tag effects will be monitored in the field by comparison with control groups of animals radio-tracked with smaller tags. Subject to funding, tags will be deployed on animals breeding on South Georgia or other sub-Antarctic islands.