These Photos Are the First to Show Humpback Whales Mating—and Both Are Males

Humpback whales are some of the biggest animals on the planet, and they live in all the world’s oceans. But despite their large size and widespread population, these gentle giants remain largely a mystery to scientists. Many of their behaviors have never been documented before.

Now, for the first time ever, citizen scientists have photographed two humpback whales copulating. Even more surprising? Both whales were male, according to a new study published last week in the journal Marine Mammal Science.

The images offer new insights into humpback whale interactions, including the positions the creatures may assume while mating. In addition, scientists can now add humpback whales to the long list of animals known to engage in same-sex sexual activity, including bottlenose dolphins, bison and dragonflies.

More broadly, the images suggest that researchers should take a closer look whenever they spot two adult humpback whales swimming together in the future.

“A pair of adult whales together may not have drawn a researcher’s attention under normal circumstances,” says study lead author Stephanie Stack, a biologist at the Pacific Whale Foundation, to Scientific American’s Melissa Hobson. “Now that we know this, maybe we’ll look a little more carefully.”

Photographers Lyle Krannichfeld and Brandi Romano were on a boat in the Pacific Ocean near Maui, Hawaii, on January 19, 2022, when they came across two humpback whales. They shut off the vessel’s engines, submerged their waterproof cameras and started snapping photos.

For 30 minutes, they watched and photographed the two whales. Several times, Whale B approached Whale A from behind and appeared to hold onto Whale A using his pectoral fins. The photographers knew sexual activity between humpbacks had never been observed before, and they thought their images might prove useful to scientists.

“We realized pretty quickly that there was a scientific significance to it,” Krannichfeld tells NBC News’ Matt Lavietes. “Even if there were no articles published or nothing ever came of it, we knew that it was important to the scientific community and those who were studying the whales just because of the unique behavior.”

So, when they got back to shore, they sent the photographs to Stack. Upon closer inspection, she realized that, not only had the photographers captured the first-ever images of humpback whale copulation, but that they had photographed two males engaging in sexual activity.

The images show Whale B using his penis to shallowly penetrate Whale A’s genital slit, an opening that hides a humpback whale’s penis when it is not mating.

“When I saw [the photos], I was just stunned,” she tells National Geographic’s Jason Bittel.

My latest research paper is published!

For the first time ever, we documented copulating humpback whales - and then we discovered that they were both males https://t.co/LWxwHP8akM@PacificWhale @marinemammalogy

— Stephanie Stack (@StephanieHStack) February 28, 2024

Stack also used photos of the whales’ tails, or flukes, to determine their ages: Whale B was around 30 years old, while Whale A was roughly 13 years old, reports Scientific American. She reached these conclusions using Happywhale, a massive citizen science database that uses artificial intelligence to identify individual whales based on their unique fluke markings. (Scientists recently used the same database to show that 7,000 humpback whales likely starved to death in the North Pacific Ocean in the mid-2010s because of a marine heatwave known as “the blob.”) Happywhale also confirmed the animals were both males.

Scientists don’t know why the two male whales were copulating, but they have a few theories. Generally speaking, scientists think animals engage in homosexual behavior to form social bonds, reduce tension and practice mating, among other possible reasons.

In this specific situation, the male humpback whales may have had higher-than-normal hormone levels because it was mating season. In that heightened physiological state, Whale B may have been exerting dominance over Whale A.

That theory is supported by the fact that Whale A was sick and injured. Whale A was covered in whale lice—which turned his body an unusual brown color—and had a severe jaw injury, likely from being struck by a boat. Whale A was also extremely thin, likely because the jaw injury made it difficult to feed.

“It looks like [Whale B] took advantage of the weak individual,” says Olaf Meynecke, a marine scientist at Griffith University in Australia who was not involved with the new paper, to Scientific American.

It’s also possible that Whale A and Whale B knew each other, and that Whale B may have been trying to bond with—or even comfort—Whale A. Alternatively, they may not have known each other previously, and Whale B may have simply mistaken Whale A for a female.

Whatever the reason, Stack urged onlookers to avoid anthropomorphizing the whales.

“Given how little we understand about humpback whale reproduction, and how much we’re still understanding about their social dynamics, I wouldn’t venture a guess as to exactly what motivated the behavior,” she tells National Geographic.

Same-sex sexual activity has been observed in more than 1,500 species of animals, according to an October 2023 study published in the journal Nature. And that number is probably an underestimation, because biologists aren’t usually studying the behavior specifically, per National Geographic.

“There is no good, there is no bad,” says Jackie Hildering, communications director at the Marine Education and Research Society in British Columbia who was not involved with the study, to the Canadian Broadcasting Corporation’s (CBC) Sheena Goodyear. “It’s just wild behavior.”

Sarah Kuta | READ MORE

Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.