Using animal-borne cameras to study the foraging behaviour of large marine predators

Abstract

Studying the behaviour of marine animals is challenging; however, the use of animal-borne instruments has great potential to contribute to our understanding of the foraging behaviour of marine predators. Data from animal-borne cameras deployed on leatherback turtles (Dermochelys coriacea) and harbour seals (Phoca vitulina concolor) were used to describe foraging behaviour and provide support for the profitability of the long distance migrations (1000s of km) of turtles. I estimated that turtles consumed a daily energy intake of jellyfish that was 3-7 times their daily metabolic requirements, a result consistent with estimates of mass gain prior to southward migration. Dive data and prey encounter data from harbour seals supported seven of the nine tested predictions of optimal diving models, but these theoretical models did not capture the complexity of the animals’ foraging behaviour. This study demonstrates the potential for using animal-borne cameras to describe and quantify foraging behaviour as well as to test theoretical optimality models.