CIE Spotlight: Influence of intrinsic variation on foraging behaviour of adult female Australian fur seals

John A.

John A.

Title: Influence of intrinsic variation on foraging behaviour of adult female Australian fur seals

Authors: Hoskins, A. J.; Costa, D. P.; Wheatley, K. E.; Gibbens, J. R.; Arnould, J. P. Y.

Source: MARINE ECOLOGY PROGRESS SERIES, 526 227-239, APR 22 2015

Brief summary of the paper: : Phenotypic variation and individual experience can create behavioural and/ordietary variation within a population. This may reduce intra-specific competition, creating a bufferto environmental change.

This study examined how intrinsic variation affects foraging behaviourof Australian fur seals. Foraging movements of 29 female Australian fur seals were recorded usingFastLoc GPS and dive behaviour recorders. For each individual, body mass, flipper length andaxis length were recorded, a tooth was sampled to determine age, and milk was collected for dietanalysis.

Clustering of fatty acid dietary analysis revealed 5 distinct groups in the population. Behaviour was described using 19 indices, which were then reduced to 7 principal components(> 80% of the behavioural variation). Bayesian mixed effect models were developed to describethe relationship between these components and intrinsic variation.

No association was foundbetween diet and age or body shape; however, age had a negative relationship with component 1 (27% of variation). Older females spent less time at-sea and foraged nearer to the colony. Age hadan effect on component 5 (7% of variation), which represented haul-outs and dive depth; olderfemales made fewer visits to haul-out sites and dived deeper to the benthos.

This suggests that asanimals age they are able to utilise prior knowledge to exploit nearby foraging sites that youngeranimals are either unaware of, or have yet to gain the experience required to efficiently utilise.Mass had a negative effect on components representing the directedness of a foraging trip, sug-gesting heavier individuals were more likely to travel directly to a foraging site.