Title
Chapter Title: Mating games and raiding parties in southern sea lions
Book Title: Ethology and Behavioral Ecology of Otariids and the Odobenid
Author(s)
Campagna, Claudio;Le Boeuf, Burney;Bisioli, Claudio
Published
2021
Abstract
We review mating systems of the South American or southern sea lion, Otaria byronia, in Argentina and Uruguay, over the last five decades. Social and environmental variables determine whether males defend territories containing females or defend females directly. Variables that influence the mating strategy include: the geophysical substrate, ambient temperature, access to water and cooling, sex composition and population status. Males defend territories if the substrate is suitable, such as containing ledges and outcroppings that serve as boundaries, flat surfaces as parturition sites for females, and tidepools for females to cool off when the temperature rises. When these conditions do not exist, and the breeding area is uniform, males defend up to 4–5 females directly. Peripheral, bachelor males attempt to acquire females by raiding the breeding units, individually or in groups. Raids are disruptive and injurious to females and pups, and few raiders acquire females. Raids occur less frequently, involve fewer males, and are less disruptive today than the group raids of the 1980s. The difference is due primarily to the changes in physical configuration of breeding areas, which forces females to spread out horizontally, decreasing opportunities for raiding. We conclude that male southern sea lions defend territories when possible but can switch to defending females directly. The physical conditions and environmental context determines the optimal social strategy.
Keywords
Southern sea lion;Otaria byronia;Otaria flavescens;Group raids;Mating systems;Female defense polygyny

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