Abstract: The underwater vocalizations of Atlantic walruses, Odobenus rosmarus rosmarus, were recorded during the breeding season at a polynya in the Penny Strait region of the Canadian High Arctic from 1983 to 1989. Mature male walruses emitted two predominant song types, a coda song and a diving vocalization song (DV song). These consisted of a short and long variation of the coda song and a short variation of the DV song that was heard sporadically. The basic structure, organization and temporal characteristics of these song types and variations did not change over the study period. Most males (78%) breeding at the polynya emitted either coda or DV songs 75% of the time that they were engaged in vocal display behaviour. The remainder of the repertoire was comprised of either intermediate songs where the males switched from one song type to the other or aberrant songs that were not recognizable as either song type. In 1988 and 1989, there were significant year-to-year changes in the predominant song type emitted by males in the polynya. It is not certain whether new males moving into the polynya, or perhaps more dominant resident males, influence which song type is emitted during a particular breeding season. Walruses significantly shortened the total duration of their songs and spent more time at the surface when they were attending a herd of females or singing near females as compared to when they sang alone. The duration of singing bouts for some males varied from 8 to at least 65 h and there was a tendency for song type and song duration to vary as the bout progressed. The singing behaviour of male walruses appears to reinforce dominance status in the absence of fighting, suggesting that intra-sexual selection has been important in the evolution of song.
Key Words: ODOBENUS; ODOBENIDAE; WALRUS; BREEDING; BEHAVIOUR; VOCALIZATION; VOCAL BEHAVIOUR; CODA; SONG; TYPES.
Document Type: Research article