Using drone technology, researchers were able to film sperm whales headbutting each other, as well as the surrounding behavioral and social context. The images were filmed during fieldwork in the Azores and Balearic Islands between 2020 and 2022.
The paper, published in Marine Mammal Science, also shows how sub-adult whales engaged in this headbutting activity, rather than between large males as was previously hypothesized. This new discovery raises intriguing questions about the function and consequences of such behavior on group cohesion and social dynamics.
Lead author Dr. Alec Burlem, who carried out the research whilst at the University of St Andrews in collaboration with researchers at the university of the Azores and Asociación Tursiops (an NGO based in the Balearic islands), said: “It was really exciting to observe this behavior, which we knew had been hypothesized for such a long time, but not yet documented and described systematically.”
More observations will be needed to understand the function of this behavior, but the widespread use of drones in the field will offer increased opportunities for observations of this, as well as other, as yet unseen, near-surface behaviors. There is speculation as to whether sperm whale headbutting may have originated from physical contests between sperm whales. Some hypothesized that this behavior may be a widespread part of male-male competition but occurs under the surface and therefore is difficult to observe from boats. Others argued that habitually using the head as a weapon was unlikely to have been favored by evolution, as it would endanger structures in the head that are vital for producing sounds used for echolocation and social communication.
The use of the head by sperm whales to push and strike objects has been reported anecdotally since the open-boat whaling of the 19th century. The most famous example is that of Essex, a 27 m sail-powered whaleship which was reported to have been sunk by two head-on strikes from a large bull sperm whale off the Galapagos in 1820, and which inspired Herman Melville’s novel Moby Dick, Owen Chase, First mate upon the Essex, described the force of the whale’s headbutt in a contemporaneous report quote:
“I turned around and saw him about one hundred rods [approx. 500 m] directly ahead of us, coming down with twice his ordinary speed of around 24 knots, and it appeared with tenfold fury and vengeance in his aspect. The surf flew in all directions about him with the continual violent thrashing of his tail. His head about half out of the water, and in that way he came upon us, and again struck the ship.”
Other similar accounts of whaling ships being sunk by sperm whales include the sinkings of Ann Alexander and Kathleen in the 19th century.
Dr. Burslem, who is now based at the University of Hawaii, added: “This unique overhead perspective for observing and documenting near-surface behavior is just one of the ways drone technology is transforming the study of wildlife biology. It’s exciting to think about what as-yet unseen behaviors we may soon uncover, as well how more headbutting observations may help us to shed light on the functions the behavior may serve. If there are people out there with similar footage, we would be very keen to hear from them.”
