1988, Campagna et al. 1992, Campagna et al. 1992, Cappozzo et al. Behavior Otaria byronia are social, group living animals. These groups usually consist of multiple females and one to several males who defend the territory. Males, called bulls, actively patrol their grounds, threaten intruders, and advertise their territorial boundaries through vocalizations. However, fights between the bull and any intruder are rare unless the intruder tries to take over the territory.
Fights are most prominent between two bulls during the initial phase of the breeding season.
The number of fights between males increases as the number of females in heat increases. Bulls let out vocal grunts and attack each other by biting and tearing. During these fights, many pups are stepped upon and killed. Bulls may maintain their territories for 2 to 3 mating seasons before another bull takes over. The bull's territory range is highly dependent the presence of cows rather than topological features or size.