Watch sperm whale headbutt another for no apparent reason

Scientists have captured first-of-its-kind footage of a sperm whale violently headbutting another sperm whale out of the blue.

Researchers filmed the clip with a drone during fieldwork off the Azores and Balearic Islands. It is one of three cases of headbutting between 2020 and 2022 that the scientists reported in a new study published Monday (March 23) in the journal Marine Mammal Science.

"It was really exciting to observe this behaviour, which we knew had been hypothesised for such a long time, but not yet documented and described systematically," study lead author Alec Burslem, a quantitative physiological ecologist at the University of Hawaii, said in a statement.

Mariners and whalers in the 18th and 19th centuries told stories of sperm whales (Physeter macrocephalus) using their heads to push each other and strike boats. The most famous anecdote dates to 1820, when an 89-foot-long (27 meters) whaleship called the Essex reportedly sank after a large male sperm whale headbutted it twice off the Galapagos Islands, according to the statement.

Reports of the Essex's sinking inspired Herman Melville's 1851 novel "Moby Dick," which tells the fictional story of a whaleship captain's obsessive and vengeful quest to find a giant white sperm whale that bit off his leg.

However, until now, scientists had never documented sperm whales' headbutting behavior.

It's still unclear exactly why sperm whales headbutt each other, but some researchers think the behavior originated from competition and physical contests between males, according to the statement. Other experts argue that headbutting is unlikely to have evolved as a widespread behavior in sperm whales, however, because using the head as a weapon can damage brain structures in these whales that are vital for echolocation and social communication.

The footage showed young males participating in headbutting, rather than mature males as was previously hypothesized, raising questions about the role of the behavior in whale groups.

It's possible that headbutting is common in sperm whales, and that researchers are only seeing it now thanks to better and more accessible technology.

"This unique overhead perspective for observing and documenting near-surface behaviour is just one of the ways drone technology is transforming the study of wildlife biology," said Burslem, who was at the University of St Andrews in Scotland when he did this research.

"It's exciting to think about what as-yet unseen behaviours we may soon uncover, as well [as] how more headbutting observations may help us to shed light on the functions the behaviour may serve," he said. "If there are people out there with similar footage, we would be very keen to hear from them."

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