Summer vocalisations of adult male white whales (Delphinapterus leucas) in Svalbard, Norway

Sammendrag

The principal aim of this study was to describe the vocalisations produced by the largely unstudied white-whale population in Svalbard, Norway. It was found that Svalbard's white whales produced most of the vocalisations that have been documented in other populations, but they also displayed minor vocal novelties and differences. A subjective classification suggested 21 call types, which were dominated by a variety of whistles. A statistical classification (cluster analyses) produced 11 groupings (after exclusion of general pulsed call types), which contained fairly logical grouping of the subjectively determined call types. However, neither method of classification employed was considered ideal for classifying white-whale vocalisations because of the highly graded nature of the calls. The white whales in this study were most vocal during milling and joining behaviours. A surprising result in this study was how little time white whales in this area spent vocalising. Their relative silence could possibly be: (1) an anti-predator strategy in response to killer whales (Orcinus orca); (2) a result of the type of schools encountered during this study (all-male grouping); (3) a by-product of the presence of the research boat in an area where whales are not accustomed to boat traffic; or (4) a result of the limited behavioural repertoire covered in this study. More extensive studies of acoustic behaviour of this population, which include various age and sex classes, with broader seasonal coverage that includes more potential behavioural contexts, are required before firm conclusions can be made regarding geographic trends in white-whale acoustic behaviour.