First photos show male humpback whales attempting to mate, hinting at homosexuality in mammal

Younger whale penetrated older one from behind while appearing to hold it in place with its pectoral fins

Researchers have captured the first-ever images of two male humpback whales engaging in sex, hinting at signs of homosexuality in the marine mammal.

Humpback whales, which grow up to 18m (60ft) long and weigh over 36 tons, are one of the largest known animals in the world and have been studied by scientists for decades.

But their sexual behavior has largely remained undescribed as it happens mostly several feet underwater, scientists say.

Previous research has found that they spend the summer months feeding in polar waters and migrate during winter to tropical waters, where their observed behaviors are related to reproduction.

Now, scientists have documented for the first time sexual activity between two male humpback whales.

Two adult male humpback whales seen off Maui, Hawaiʻi, on 19 January, 2022 (Lyle Krannichfeld and Brandi Romano/Marine Mammal Science)

Sexual interaction between individuals of the same sex is seen in a wide range of animals, and among marine mammals, it has been documented well in walruses, gray seals, as well as in Amazon river dolphins.

The new research documents homosexual behaviour between an older male humpback whale that appeared unhealthy or injured, and a strong and healthy young male whale.

The observation was made opportunistically in January 2022 when a private vessel encountered two humpback whales approximately 2km west of the Molokini crater off the island of Maui, Hawaii.

As the whales slowly approached the boat just below the surface, researchers could observe them.

One of the whales (Whale A), visibly an older one, appeared to have an unusual brown coloration of the body, and appeared emaciated and covered in whale lice, scientists say.

Two adult male humpback whales seen off Maui, Hawaii in January, 2022. Whale B has its penis inserted into the genital opening of Whale A. (Lyle Krannichfeld and Brandi Romano/Marine Mammal Science)

Researchers found the whales interacting with each other and slowly circling the boat several times.

The second whale (Whale B), scientists observed, had its penis extruded during the entire encounter as it repeatedly approached from the rear of the older whale and penetrated it while appearing to hold it in place with its pectoral fins.

“Whale B had its penis extruded throughout the entire encounter and, at times, would penetrate the genital opening of Whale A, using its pectoral fins to hold,” scientists added.

“Here, we have the first documentation of a humpback whale male sexually penetrating another humpback whale, but also the case of an animal that is injured and unhealthy being penetrated by what appears to be a healthy and strong whale,” they wrote.

Due to limited data on such sexual encounters, scientists call for further research to explore the “motivations, implications, and potential factors” influencing such interactions.