Groans and grunts, whistles and woops—these are some of the many sounds you can hear when listening to humpback whales singing. Although humpback whale song is one of the most widely recognized animal sounds, surprisingly little is known about its purpose. This is not for lack of effort: scientists have been studying different aspects of these songs for decades, leading them to develop some theories about what might motivate a whale to sing.
Only male humpback whales sing, which suggests the song is likely a mating display similar to bird song. One of the first theories for why whales sing was that perhaps the males were singing to attract females, but that idea has been consistently debunked through multiple studies where scientists played humpback song to breeding females in the area. Interestingly, these playback studies often resulted in males approaching the source of the played song, sending researchers back to the drawing board.
Why would a male humpback whale approach another male on the breeding grounds? Since song doesn’t seem to attract females, it is more likely that males are singing to communicate with other males. A popular theory surrounding this idea is that the males might use songs to coordinate their behavior. While singing, a male humpback is advertising his position whether he wants to or not. This could invite competition from other males, or those other males might be looking for partners in an alliance. Alliances between male humpback whales have been observed in competitive groups and might help males displace other competitors.
The other prevailing theory for male singers joining each other involves a type of mating display called a “lek”. Leks occur when multiple males display together, allowing females to choose the best from the group. In this sense, reproductive females might be initially attracted to the lek by the broad signal of several chorusing males, and males benefit from conserving energy otherwise spent searching for those females.
None of these theories necessarily exclude the others, and humpback whales may use their songs in different ways depending on the time of the season, other whales in the area, and characteristics of each individual. Although researchers at Pacific Whale Foundation are not currently studying humpback whale acoustics, we appreciate the importance of singing to these amazing animals.