Overview
- The peer‑reviewed case study published Nov. 2, 2026 in Current Biology documents a repeated, selective sexual and social relationship between Achille, a bull, and Patroclo, a male donkey, on an Ethiopian plateau.
- Researchers recorded 51 mountings between the two across intensive observations in March and noted reciprocal affiliative behaviors such as licking, rubbing, nuzzling, hindquarter presenting, and avoidance by other males.
- The team reports both animals had access to other potential mates and owners on the plateau, which they say makes a simple ‘no-available-partner’ explanation unlikely.
- External experts warn the finding is limited by the sample size of two and by domestication, saying the behavior may not reflect patterns in wild populations and that larger, systematic studies are needed.
- Herders on site treated the pair as a familiar sight, the animals have since been grazed separately, and the authors say the case raises broader questions about how social bonds shape sexual behavior across species.