Dive behaviour of male Australian fur seals: evidence of individual specialisation

Predicting how apex predators will adapt to increased environmental variability is a critical component underpinning effective ecosystem management. However, it first requires a thorough understanding of the foraging... [ view full abstract ]

Predicting how apex predators will adapt to increased environmental variability is a critical component underpinning effective ecosystem management. However, it first requires a thorough understanding of the foraging strategies of species at both the population and individual levels. Australian fur seals, Arctocephalus pusillus doriferus, have long been considered a species comprising of ‘generalist’ individuals, making populations susceptible to environmental variability. Investigation into the diving behaviour of 16 adult males tagged at Kanowna Island in south-eastern Australia over a two year period (2013-14), have revealed that the foraging ecology of the species may be far more complex than initially described. Analysis of over 75,000 dives suggests that males, like their female conspecifics, employ a predominantly benthic foraging strategy (mean max depth 69.0 ± 0.1 m; max = 87.5 m) within the continental shelf. However, further examination provides evidence for individual specialisations (for example, temporal and seasonal differences in foraging effort). This variability in foraging behaviour observed between male individuals are likely a direct result of intra-specific competition. Furthermore, it is expected that these behavioural specialisations may lead to further resource partitioning, within other aspects of their foraging ecology (e.g. dietary niche). Understanding such specialisations within the foraging ecology of male Australian fur seals, can provide insight into the potential for the species to adapt to environmental change, at both an individual and population level. Consequently, while some individuals may succumb, the Australian fur seal as a species, may be less vulnerable to environmental variability than previously thought.