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PWF Researcher Documents First-Ever Humpback Whale Copulation

On January 19, 2022, off the coast of Maui, Hawai‘i, an unprecedented event was recorded for the first time — two humpback whales copulating.  While this observation is remarkable on its own, this story has a remarkable twist – the encounter involved two male whales.

Humpback whales have long been subjects of fascination for researchers due to their intricate social behaviors, many of which are thought to relate to reproduction. Despite being extensively studied for decades, the sexual behavior of humpback whales has remained mostly a mystery, even for whale experts. However, a Pacific Whale Foundation researcher recently unveiled a historic finding—the first-ever documented copulation in humpback whales!

Published on Feb. 27, 2024 , the article reports a significant breakthrough in our understanding of humpback whale behavior. The observation, made on January 19, 2022, off the coast of Maui, Hawai‘i, reveals an unprecedented event—humpback whales engaged in copulation for the first time in recorded history.

Stephanie Stack, lead author of the paper and a whale researcher with the Pacific Whale Foundation, was contacted by two Maui-based photographers for advice regarding a unique encounter that they had documented while boating recreationally. What they stumbled upon was an unprecedented observation. The groundbreaking photographs captured by Krannichfeld and Romano provide an unparalleled glimpse into the private lives of these majestic marine mammals.

The sighting occurred when individuals aboard a private stationary vessel, located approximately two km west of the Molokini crater, saw two humpback whales approaching their boat. One whale was visibly thin and covered in whale lice, displaying signs of poor health and drawing the attention of the photographers. During the encounter, a second whale engaged in an unexpected behavior—repeatedly approaching the first whale, using its pectoral fins to hold the injured whale in place, and initiating shallow, brief penetrations. The two whales circled the boat numerous times, allowing Krannichfeld and Romano the opportunity to carefully document the event by holding their cameras over the side of the stationary vessel (note: it is illegal to swim with or approach humpback whales within 100 yards in Hawaii and the vessel remained in neutral as the whales approached). The health disparity between the two whales adds a layer of complexity to this unique observation. One whale’s poor condition, possibly caused by a ship strike, may have contributed to the observed behavior.

Although this is the first time it has been reported for humpback whales, homosexual behavior is common in the animal kingdom and well documented for many species of cetaceans. The first documented copulation between humpback whales adds valuable details and knowledge toward our understanding of these magnificent creatures, offering fresh insights into the reproductive behavior of this species.

The article titled “An observation of sexual behavior between two male humpback whales” is now published in the journal Marine Mammal Science and is available to read here: