Protected since 1970 following decades of whaling, sei whale numbers are increasing, with waters around the Falkland Islands a uniquely large gathering area in spring and autumn.
To learn more about their population recovery and why sei whales like these waters so much, Falklands Conservation and the African Aquatic Conservation Fund backed a long-term study, now reported in Royal Society Open Science.
For this, researchers Salvatore Cerchio and Caroline Weir analysed a huge dataset collected from continuous sound recordings made from the seabed.
At first, the team was baffled by the ‘other-worldly’ noises they heard, but deeper analysis revealed organised and repeated sei whale phrases. The sounds are very different to the rich and resonant courtship calls made by humpback whales and are more like eerie swishes and whooshes.
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“The discovery of a complex structured song for sei whales was truly a great surprise,” says Salvatore Cerchio. “The characteristics of the songs and their seasonal timing makes it very likely these songs are a male breeding display.”
Discovery of the songs further highlights the global importance of Falklands waters for the species, say the researchers.
Main image: Sei whales. © Dr Caroline Weir/Falklands Conservation