Specialization and development of beach hunting, a rare foraging behavior, by wild bottlenose dolphins (Tursiops sp.)

Abstract

Foraging behaviors of bottlenose dolphins vary within and among populations, but few studies attempt to address the causes of individual variation in foraging behavior. We examined how ecological, social, and developmental factors relate to the use of a rare foraging tactic by wild bottlenose dolphins (Tursiops sp. Gervais, 1855) in Shark Bay, Western Australia. Beach hunting involves partial and nearly complete stranding on beach shores. Over 10 years of observation, only four adults and their calves were observed beach hunting in more than 1 year. Of two adult beach hunters observed in detail, one was more specialized in beach hunting than the other, indicating substantial flexibility in degree of use. Only calves born to beach hunters developed the tactic, although complete stranding was not observed at least up to 5 years of age. Beach hunters used shallow, inshore habitats significantly more than others and were more likely to hunt during incoming tide. Mitochondrial DNA haplotypes were not consistent with strict matrilineal transmission. Thus, beach hunting likely involves vertical social learning by calves, while individual, horizontal, and (or) oblique learning may occur among individuals who frequent coastal habitats.