Social Ecology of Feeding in an Open Ocean

Abstract

Odontocetes typically live in groups, and strengths of associations among individuals likely affect coordination of behaviors while avoiding predators, having sex, rearing young, and locating, containing, and capturing prey. In this chapter, I concentrate on food. In determining "good" locations to search for prey, odontocetes likely use prior knowledge about their environment, either newly acquired or shared by others. To locate prey, odontocetes use a combination of echolocation, hearing, and sight, and these sensory as well as other potential modalities are likely combined in subtle ways to facilitate searching for prey as a group. After locating prey, toothed dolphins and whales at times work together to contain prey. Social prey containment occurs if the costs of containing prey increase feeding efficiency sufficiently to make it worthwhile to expend the energy. Benefits of coordinating behaviors to capture prey include increasing capture efficiency by working together to briefly disorganize a fish school, trap prey between dolphins, or debilitate prey. While much of this chapter focuses on epipelagic and mesopelagic odontocetes, we are learning more about how deep-diving dolphins and whales forage, and coordination there seems likely as well.