Vocal recognition of individuals versus relative dominance rank among breeding male northern elephant seals (Mirounga angustirostris).

Abstract

Whether an animal truly recognizes an individual or a simple rule-based category (e.g. neighbor or offspring) has important behavioral and evolutionary implications such as the accuracy of social reciprocity. Many tests of individual recognition have focused on neighboring territorial males (dear enemy or neighbour-stranger recognition). Unfortunately the static territorial context of these tests, mostly with male songbirds, opens them to the criticism of being merely associative habituation. More dynamic mating assemblages, such as leks where vocally advertising animals encounter numerous others, are a potentially rich and largely untested alternative. The female defense polygyny practiced by male northern elephant seals during terrestrial breeding is such a dynamic system. To examine whether elephant seals were recognizing individuals or dominance categories we conducted a total of 53 playback experiments to 18 males at Ano Nuevo State Reserve. Each playback was a series of threat calls assigned to four dominance conditions relative to the subject. Dominance was based on the outcomes of interactions among contesting male dyads. Responses were measured using three assays in situ and from video records of each experiment. Results indicate that males do recognize familiar individuals although responses are primarily based on relative dominance rank.