Evidence
of segregation in foraging habitat has been demonstrated in some top marine predators,
including cetaceans, pinnipeds and seabirds. However, most data are not
adequate to assess differences relating to body size or seasonal influences.
This has
implications for quantitative modelling of population-level predator–prey
interactions and ecosystem structure. We examined potential
influence of body size and ‘fatness’ on the foraging trip characteristics of a
top marine predator, the Atlantic grey seal (Halichoerus
grypus), in southwest
Ireland within the framework of optimal foraging theory to
examine how female grey seals foraging behaviour varied with size, and across the period between moult and breeding. Larger
seals undertook trips of greater duration and travelled further from haul-out
sites than smaller seals. However, body
fat was negatively associated with trip duration and extent. Seals spent more
time at sea during the summer, but trips were shorter in extent, suggesting
more localised foraging during this season