Revealing underwater secrets with new technique

Miniature cameras or sensors are often attached to animals, such as penguins and seals, to allow scientists to observe their daily activities, such as their predator-prey interactions and decision-making.

However, questions remain about specific details of their feeding behaviour, such as prey selection and foraging strategies.

In a study just published in the journal PeerJ, researchers analysed footage from animal-borne cameras on Humboldt, King and Tawaki/Fiordland penguins.

They used image-measuring software to convert the pixels to actual measurements and were able to estimate the energy content of the penguins' prey.

Lead author Owen Dabkowski, a Masters' student in the Department of Marine Science, says this is a major step forward for marine biology.

"Our work will explain why animals target certain prey over others or how much energy they gain in a single feeding period compared to how much energy they expend," he says.

"The new technique will provide a unique perspective for analysing diet composition and foraging behaviour, revealing previously unseen interactions that occur underwater."

Researchers worked in collaboration with the Tawaki Project -- a long-term study of the marine ecology, breeding biology and population dynamics of New Zealand's crested penguins -- to develop the new technique.

Supervisor Dr Ursula Ellenberg, of Otago's Department of Marine Sciences and co-director of the Tawaki Project, is pleased with the results.

"Precise prey size estimations from animal-borne video footage will significantly enhance our ability to study predator-prey interactions and energy dynamics in marine ecosystems," she says.