Foraging behavior, prey distribution, and microhabitat use by bottlenose dolphins Tursiops truncatus in a tropical atoll

Abstract

The study of habitat use by top predators is important for understanding community interactions and is necessary for sound ecosystem management. In marine systems, top predators such as sharks and cetaceans have a strong impact on the structure and function of communities. While the observation of habitat use and foraging behavior of most marine predators is logistically difficult, bottlenose dolphins Tursiops truncatus offer less of a challenge due to visible surface behavior and well-documented populations. We examined bottlenose dolphin behavior in relation to microhabitat classes at Turneffe Atoll, Belize. The dolphins were found to feed proportionally more in boundary microhabitats, areas where dense seagrass beds adjoined open sand flats, than in other microhabitats. Fish density, particularly schools of grunts (family Haemulidae), were higher in the boundary microhabitat than in seagrass or sand microhabitats. Extensive acoustic recordings yielded few fish calls, suggesting that passive listening for soniferous fish was not the dominant means of diurnal prey detection. The dolphins’ disproportionate use of boundary microhabitats for feeding was likely due to the abundance and accessibility of prey.