Fig S4 A spectrogram representation of humpback whales singing in the subarctic waters of Iceland

Fig S4. A spectrographic view of a 10 minute song recording. A spectrographic view of a 10 minute recording showing phrase sequences from songs of at least 3 different singers . The whales are appear to be singing the same song but asynchronously. One of the singers is likely singing closer to the hydrophone than the other two since the song units of that singer‘s song are clearer on the spectrogram (with greater SNR). Such circumstances may make it easier for observers to delineate the songs found in the recording if there is a regular overlap of song units from different singers.