Knowledge of the factors shaping a species' foraging behaviour is central to understanding its ecosystem role and predicting its response to environmental variability. To maximise survival and reproduction, foraging strategies must balance the costs and benefits related to time and energy needed to search, chase, capture, manipulate and consume prey with the nutritional reward obtained. While such information is vital for understanding how changes in prey assemblages may affect predator species, determining these components is inherently difficult in cryptic predators such as marine mammals. This study used animal-borne cameras to study costs and benefits related to different prey types in female Australian fur seals (Arctocephalus pusillus doriferus) and found that although chase and handling times, captures successes, energy gain and energy expenditure varied between prey types, prey profitability did no differ. The low marine productivity in Bass Strait and its effect on prey availability may influence the foraging mode of the Australian fur seal, they are known to be predominantly benthic foragers as profitability of benthic prey outweighs searching costs associated with nutritious, pelagic baitfish prey. Anthropogenic-induced changes in the marine environment may however cause increases in baitfish abundance, which may facilitate the switch towards a more epipelagic foraging mode. |
