‘It’s really, really unusual’: tender bond between male donkey and bull baffles scientists

Patroclo and Achille’s interspecies affair sheds new light on social and sexual relations between animals, scientists say

In ancient myth, Achilles and Patroclus were two Greek heroes of the Trojan war whose intense bond was believed by some to have turned into a sexual relationship.

In modern science, they are a bull, Achille, and a donkey, Patroclo, whose tender interspecies affair has helped to shed new light on social and sexual interactions between animals.

Researchers say the two males have been spotted licking and rubbing each other, with the bull sometimes mounting the donkey.

The team said while other donkeys attempted to avoid Achille’s attentions and showed threatening facial expressions towards him, Patroclo often presented his hindquarters to Achille and nibbled him.

“It is really, really unusual,” said Dr Elisabetta Palagi of the University of Pisa in Italy, who co-authored the study. “And it is the first time it is reported in literature.”

André da Cruz, a PhD student at the University of Pisa and another author, said the relationship had been discovered by accident while the researchers studied geladas, or bleeding-heart monkeys, in Ethiopia.

“We were having a little break for lunch, and in the distance I see something – it seemed a bit odd,” said da Cruz. “I told colleagues: ‘I think I saw a bull mounting a donkey.’ And they didn’t believe me.”

Writing in the journal Current Biology, the researchers said the bull and the donkey belonged to different owners and only came into contact with each other when, as part of their daily routine, their herds used the same pasture.

The researchers studied Achille and Patroclo over four days when they were both grazing in the same area, and four days when only one was present.

The team not only recorded 51 mountings of Patroclo by Achille, but noted licking and rubbing often occurred before and, more surprisingly, after such events.

“Rather than being solely attributable to sexual arousal, these interactions appear to play a role in prolonging the social interaction beyond the sexual act,” they wrote.

Despite ample opportunity, neither Achille nor Patroclo tried to mount a member of their own species of either sex, although Achille did show courtship behaviours towards some female cattle.

While rare, there have been other examples of interspecies hanky-panky, including a case of a male snow monkey attempting to have sex with female sika deer, and an Antarctic fur seal that not only sexually harassed king penguins but engaged in necrophilia.

However, Palagi said there was no indication that the relationship between the donkey and the bull involved force.

“We interpret our data as a special relationship,” Palagi said, adding that the two males searched for each other. “When Achille approached someone else in the plateau, Patroclo went to him and tried to distract him,” she said.

Da Cruz said the mounting behaviour of Achille was unlikely to simply be a case of the bull exerting dominance.

“We saw on several occasions what might have been semen from the bull, or he might have been orgasming, although we cannot verify [that] completely,” da Cruz said, adding that Patroclo was highly aggressive to bulls other than Achille.

Palagi added that the relationship was an example of a sexual interaction that was disentangled from reproductive function.

“When two individuals belonging to the same species or different species need to develop a special relationship, they fish simply from their entire [behavioural] repertoire,” she said.

Palagi said it was unclear whether the sexual and social relationship between Patroclo and Achille had always co-existed or if one had led to the other. But, she added, the bond appeared to bring benefits, both in terms of attention but potentially also support.

Josh Luke Davis, the author of A Little Gay Natural History, said interspecies relationships were not necessarily unusual and that the widespread and common nature of queer behaviours in the natural world meant it was “probably not that surprising” that they overlapped.

“There is obviously value in reporting these kinds of behaviours,” Davis added. “But I would caution against reading too much into the significance of it and would be concerned about how it could be misconstrued or twisted by those who already deem homosexuality ‘unnatural’.”