UC Santa Cruz

Acoustic communication is a fundamental feature of most animal social systems, and serves to support important behavioral traits such as breeding, foraging, and parental care. Despite many decades of research, detailed information regarding the role that vocal signaling plays in the social lives of marine mammals is scant. This is due in large part to the difficulties of observing the social context in which information exchange between individuals occurs, as these animals live most of their lives beneath the water’s surface. As a consequence, many questions regarding the function, ontogeny, and evolution of sounds produced by marine mammals remain un-answered. The northern elephant seal (Mirounga angustirostris) presents an opportunity to better understand the role that acoustic communication plays in mediating social interactions between competing males during the breeding season, as they are one of the few species of seal that breed on land in predictable locations each year. In this dissertation, fine-scale acoustic analyses have been paired with close behavioral observations of known adult males in the wild to determine the function of the male vocal display, and the conditions that underpin this species’ social system of extreme competition. Additionally, the unique demographic history of the northern elephant seal combined with long-term monitoring of this species offers the opportunity to examine how the vocal behavior of male seals has changed during this species’ recovery from near-extinction, and the extent to which these specialized signals have been influenced by factors such population expansion, cultural learning, and the relative abundance of seals at different breeding sites. Finally, to better understand how males navigate this system of tremendous competition, the ontogeny of spatial, social, and communicative behavior among male elephant seals is explored by tracking young males throughout maturation. Taken together, a detailed understanding of the role that vocal signaling plays in the lives of male seals emerges from these studies, and contributes broadly to comparative frameworks for studies of agonistic signaling in other animal systems.