A bull named Achilles and a male donkey called Patroclus have drawn the attention of biologists after developing a repeated sexual and social relationship in an Ethiopian pasture. Whenever their herds met, the two animals sought each other out and spent much of their time together.
Researchers from the universities of Pisa and Addis Ababa observed the pair during eight days spread across two weeks. They recorded 51 mounting events, 34 of which involved penetration. Achilles was always the one mounting, while Patroclus did not display the avoidance or defensive reactions seen when the bull approached other donkeys.
The encounters were accompanied by repeated affiliative behaviors, including licking, rubbing and touching with the muzzle. These contacts occurred both before and after mating, leading the researchers to interpret them as part of a broader social bond rather than simply sexual preparation.
The animals’ relationship stood out because both had access to members of their own species and to individuals of both sexes. Achilles occasionally attempted to mount other donkeys, but those interactions were met with kicks, threatening facial expressions or attempts to escape. In one instance, Patroclus interrupted such an attempt, after which Achilles returned to him and the donkey repeatedly presented his hindquarters.
The observations were made while a research team was studying geladas in the Ethiopian highlands. The scientists named the animals after the figures from Homer’s Iliad, known for their close friendship. The study has been published in Current Biology.
Elisabetta Palagi, an ethologist at the University of Pisa, said the pair’s sexual interactions appeared to be closely connected to a selective social relationship. However, she stressed that the researchers can document mutual preference, repeated friendly contact and sexual interactions, but cannot determine precisely what the animals experienced emotionally.
The researchers also caution that this is a single case involving males from different species and cannot be generalized. The herds later moved to other pastures during the dry season, separating the animals for several months. Palagi’s students in Ethiopia are attempting to arrange a future meeting between the herders so they can observe whether the relationship continues.
Sources: El País Ciencia.