Influence of intrinsic variation on foraging behaviour of adult female Australian fur seals
Hoskins, AJ and Costa, DP and Wheatley, KE and Gibbens, JR and Arnould, JPY, Influence of intrinsic variation on foraging behaviour of adult female Australian fur seals, Marine Ecology - Progress Series, 526 pp. 227-239. ISSN 0171-8630 (2015) [Refereed Article]
Phenotypic variation and individual experience can create behavioural and/or
dietary variation within a population. This may reduce intra-specific competition, creating a buffer
to environmental change. This study examined how intrinsic variation affects foraging behaviour
of Australian fur seals. Foraging movements of 29 female Australian fur seals were recorded using
FastLoc GPS and dive behaviour recorders. For each individual, body mass, flipper length and
axis length were recorded, a tooth was sampled to determine age, and milk was collected for diet
analysis. 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 describe
the relationship between these components and intrinsic variation. No association was found
between 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 had
an effect on component 5 (7% of variation), which represented haul-outs and dive depth; older
females made fewer visits to haul-out sites and dived deeper to the benthos. This suggests that as
animals age they are able to utilise prior knowledge to exploit nearby foraging sites that younger
animals 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, suggesting
heavier individuals were more likely to travel directly to a foraging site.
intrinsic variation, foraging behaviour, age effects, phenotypic variation