Foraging Capacities, Behaviors and Strategies of Otariids and Odobenids

Abstract

Fur seals, sea lions and the walrus (Odobenus rosmarus) are breath-hold divers that rely on swimming at depth to feed at sea. As their diving capacities are more limited than phocids, otariids and odobenids are geographically constrained to highly productive environments and relatively shallow dive depths. They are also mostly coastal species, central place foragers with relatively limited foraging ranges. Diving patterns and strategies are diverse among the otariid group—although fur seals tend to be more pelagic and sea lions more benthic divers—, and driven by extrinsic factors such as the type of habitat they occupy, environmental factors, intra- or inter-specific density-dependent competition, predation risk and the behavior of the prey they feed on; as well as intrinsic factors such as age, sex, reproduction status, size and experience. There are usually several foraging strategies present within a species, and individuals tend to specialize to one of these strategies, with a degree of adaptability to changing conditions possible. Diving behaviors and strategies define the feeding success and foraging efficiency of individuals, and as such their capacities to successfully survive and reproduce in their environment. The diversity of these behaviors within otariid and odobenid populations are likely evolutionary stable strategies that provide a buffer under changing environmental conditions.