Bull and Donkey Form Lasting Bond in Ethiopia
Owners of cattle and donkeys may see unexpected pairings form when animals graze together.
Updated on Nov. 2, 2026 in Large Animals
Ecologists documented a sustained sexual and social bond between a domesticated bull named Achille and a male donkey named Patroclo on an Ethiopian plateau. The findings were published today in Current Biology.
Why it matters
The case expands what researchers know about the range of social and sexual behavior in domestic livestock, a finding that matters for anyone who keeps or works with farm animals. Because the animals had different owners and grazed together by choice, the observation suggests that pairings between unrelated animals can form outside of breeding management.
Over four days together, Achille mounted Patroclo 51 times, and neither animal engaged sexually with other animals in the same field. The observations were paired with four days apart from each other, allowing researchers to compare behavior across the two periods.
The players
Current Biology
A peer-reviewed scientific journal that published the case study.
University of Pisa
The Italian university with which the lead researchers are affiliated.
The details
Researchers watched the animals over separate four-day stretches, once together and once apart. Patroclo was receptive when Achille mounted him but became aggressive toward other bulls nearby. After sexual interactions the two animals often licked or rubbed against each other, behavior that the study describes as part of their bond.
Timeline
Researchers observed the animals across two separate four-day periods, one together and one apart.
The study was published in Current Biology on 2026-11-02.
The Home Front
Animal behavior studies like this one add to the growing record of same-sex sexual behavior in domestic livestock, a subject that has been documented in cattle and other farm species. The Ethiopian case is notable for its field setting and for the bond formed between animals that were not kept together by their owners.
If you keep cattle, donkeys, or other large animals, observe how your animals group and pair off, since unexpected bonds can affect breeding plans and herd management. Consult a licensed veterinarian if you notice behavior that concerns you or affects animal welfare.
The takeaway
Animals form social and sexual bonds that can cross owner lines and herd boundaries, which is worth noting when planning pasture and pairing. Keep a record of unusual grouping behavior and raise it with your veterinarian during routine checkups.
Further reading
For broader context on how animals behave in domestic settings, see the Large Animals section.
