Two male lions have been seen copulating at a Yorkshire zoo in the UK by a visitor, raising familiar arguments about the prevalence of homosexuality in the animal kingdom.
The photos of the incident, caught by amateur wildlife photographer Russ Bridges, also show a female lion nearby who appears to be unfussed by the two male lions going at it next to her.
Bridges' photos of the rare sighting went viral this week, with social media users commenting on the apparent joy experienced by the two lions, especially in one image that captures a yawn while one of the lions is mounted.
"A fair few people were watching this going on and laughing - they were all commenting on what it looked like," Bridges told The Daily Mail.
"I think it was a bit of a 'should have gone to Specsavers' moment as the lioness was just lying there next to them. In fairness, though, every time a male went near her she snarled and swiped their faces with her paw.
"It's not really unusual for them to act that way sometimes. I don't know if it's a dominance thing or something like that - it looks as if they are aggressive, but it's all play between friends," Bridges said.
A similar encounter was captured last summer in northern Botswana, reported National Geographic, but a zoologist insisted it wasn't two males, but rather a female lion with a mane.
"If a lion mother had abnormally high androgens during pregnancy, her female offspring may end up 'masculinised," the zoologist says. "[It's] a situation that occurs occasionally in people, but that is rarely observed in wild animals."