Variations in the arrangement of South American sea lion (<I>Otaria flavescens</I>) male vocalizations during the breeding season: patterns and contexts

Abstract

We analysed whether South American sea lions (Otaria avescens) varied the syntax or arrangement of vocalizations (the order in which calls were produced) according to diVerent social contexts. Three male calls that formed a progression of increasingly aggressive displays (growl<bark<highpitched call) were studied in a breeding colony at Península Valdés. We found that: (a) growls and barks had higher probabilities of emission than high-pitched calls, (b) vocal bouts generally were initiated by growls, (c) the transitions most likely to occur were growl-bark and bark-growl, and (d) the number of male-male agonistic interactions (highpitched call after growl, bark after growl) and the number of neighbour males (growl after highpitched call) aVected some transitions between call types. The baseline vocal display of males consists of a sequence of growls and barks given in succession (e.g., growl-bark-growl-bark), which can incorporate high-pitched calls during highly aggressive male-male interactions. Vocal arrangement variations could be a strategy to modulate agonistic behaviour during vocal displays and to increase the chances of being detected in noisy breeding colonies.