Far from “mourning the loss of his mate”, the male kangaroo pictured in “heartbreaking” viral photographs with its injured female “companion” might have been responsible for her death while attempting to mate with her, experts say.

The images, taken on a bushland property in River Heads, Queensland, Australia, show a male eastern grey kangaroo holding the head of a dying female, in front of her joey.

Photographer Evan Switzer said the kangaroo was acting protectively.

“I saw the male pick up the female, he looked like he was just trying to get her up and see what was wrong with her … It was a pretty special thing, he was just mourning the loss of his mate.”

He added that he’d never seen a kangaroo act that way before – and he had seen a lot of dead kangaroos.

The media that reported on his striking images also interpreted the interaction as a touching display of a “marsupial family’s grief”, with the male kangaroo propping up the female’s head “so she could see her joey before she died”. The joey, in turn, had “touched her softly” to say goodbye.

But Dr Derek Spielman, a senior lecturer in veterinary pathology at the University of Sydney, told Guardian Australia that he had “no doubt” that the male was in fact attempting to mate with the female animal – and might have caused the injuries that she died from.

He said the photographs showed the male kangaroo “mate guarding” – holding other males at bay.

“Competition between males to mate with females can be fierce and can end in serious fighting,” he said. “It can also cause severe harassment and even physical abuse of the target female, particularly when she is unresponsive or tries to get away from amorous male.

“Pursuit of these females by males can be persistent and very aggressive to the point where they can kill the female. That is not their intention but that unfortunately can be the result, so interpreting the male’s actions as being based on care for the welfare of the female or the joey is a gross misunderstanding, so much so that the male might have actually caused the death of the female.”

Spielman added that, though he thought the term was often misunderstood and misused, the reporting of the viral photographs had been “naive anthropomorphism”.

Eastern grey kangaroos can breed throughout the year, but mostly do so in spring and early summer.

The kangaroo’s “sinister” intentions were first flagged in an explosive blog post by Dr Mark Eldridge, the principal scientist of the Australian Museum. He praised Switzer’s “great photos of the kangaroos”, but said they had been “fundamentally misinterpreted”.

“This is a male trying to get a female to stand up so he can mate with her,” he said.

He pointed to the “highly stressed and agitated” state of the male kangaroo, which had been licking its forearms to cool down. Eldridge also pointed to “evidence … sticking out from behind the scrotum” of the kangaroo’s sexual arousal.

Interest in the blog post caused significant delays to the museum’s website.