Humpback whale calls can persist across multiple generations, but songs change frequently, according to a study published in Scientific Reports.
Whales produce songs, which are long, repetitive vocal displays, and calls, which include any vocal sound produced outside the patterned and repeated structure of a song. Michelle Fournet and colleagues investigated the stability of humpback whale calls (non-song vocalizations) by comparing the earliest known recordings from the 1970s with recordings from the 1990s, 2000s, and 2010s. They found that some whale calls did not change over a 36-year period; in contrast to whale songs, which change frequently.
Of 16 humpback whale call types produced in Southeast Alaska, the authors found that 12 were detected in both 1976 and 2012, demonstrating the persistence of these calls over 36 years. The researchers found eight call types that were present in all four decades, and every call type was present in at least three decades. The stability of whale calls across generations compared to the changing nature of whale song suggests whale calls may have a different purpose that requires them to remain the same; for example, organizing the social structure of whale groups or coordinating foraging. Stability may therefore be as important in calls as novelty is in whale song, which plays an important role in mating.