Do Blue Whales Serenade Their Partners?

Besides surface observations, another clue has recently been decoded to help researchers better understand whales’ reproductive jargon. The acoustic recordings of the communications of the three trios were correlated with observations of the courting blue whales. In all three cases, the trios produced calls known as “D-calls”, which are repeatedly only when the trio is being formed.

D-calls are recorded in nearly all blue whale populations in situations where some degree of social cohesion is needed, for example between a female and her calf, and are usually produced in contexts where another blue whale is in proximity. In the cases presented in the study, the D-calls recorded near the trios were repeated at short intervals. This is the first time that calls of this sort were recorded for this species. The D-calls were produced by at least two different individuals, as some of the calls overlapped.

Do blue whales serenade to win the heart of a coveted female? Not exactly. In marine mammals, a song is a series of different types of calls emitted in a specific order. In this case, it is more like a repetition of the same type of call. D-calls are produced by both males and females, unlike in humpbacks, where only males sing during the breeding season.

Does the D-call in a trio context serve to maintain the bond between the initial pair? To express the female’s interest in one male over the other? The function of these calls remains to be clarified. But from a conservation perspective, these repeated calls could soon be used as acoustic markers to detect areas where reproductive activities take place. If our hydrophones and computers can recognize certain types of calls, perhaps we can identify critical breeding locations for blue whales, an endangered species?

According to the authors, “Such information on blue whale reproductive behaviour is extremely rare, but crucial to better understand the breeding strategies of this species.”