The humpback whale song is one of the most complex, non-human, acoustic displays in the animal kingdom.
But why males sing is still a mystery. To explore this intriguing question of why humpback whales sing, Whale Trust Maui researchers have been following, recording, and tracking humpback whales singers off the coast of Maui, Hawaii since the mid-70s.
After decades of study, we are currently testing the hypothesis that the song may function as an index of association between individual males. That is, the song may be a means for individual males to recognize how closely associated they are with other males, and may determine if specific males cooperate or compete for females.
This hypothesis suggests that the changing nature of the song (with all singers in a region singing the same version at any one time) provides a measure of geographic association between males and a means of organizing male relationships in the breeding season.
This hypothesis requires testing to determine its validity. Three separate research projects supported by Whale Trust Maui are testing this hypothesis:
- Tracking the Changes of Humpback Whale Song Across the North Pacific Ocean
Working with other researchers throughout the North Pacific Ocean, Dr. Jim Darling is trying to explore the nature of how the humpback whale song changes over space and time. Does song similarity correlate with the geographical distance separating singers? In other words, do humpback whales singing in Japan share more similarities within the song with humpback whales singing in the Philippines than humpback whales singing in Hawaii? Do changes in the song move consistently from one location to another?
- How Do Humpback Singers Respond to Other Nearby Singers?
To find out, Whale Trust Maui researchers are conducting playback experiments where similar or different songs are played back to singers off the coast off Maui, Hawaii. The idea is to determine whether similarities or differences in the song determine whom singers interact with through playback experiments.
- Do Male Humpbacks Cooperate (Work Together) During Mating?
During the breeding season, humpback whales are known to actively compete with one another for a female. Indeed, surface active or competitive groups are one of the most striking humpback behaviors on the breeding grounds. But do some males also work together (cooperate) around a female? If so, how do we measure competitive versus cooperative behavior of males around females? Whale Trust Maui researchers are exploring this question buy utilizing aerial videography from both new (drones) and old (helicopter) platforms to investigate whether or not this is a common strategy used by males to obtain mates.