Ethiopian researchers document 51 interspecies sexual encounters between a bull and male donkey

Key points

• Researchers from the University of Pisa observed 51 mounting attempts between a bull and a male donkey over four days in March, with 34 instances of penetration.
• The animals, named Achille and Patroclo, lived on separate farms and only met when owners brought them to a shared grazing field.
• The donkey actively reciprocated the behavior, frequently presenting his hindquarters and showing no aggression, unlike other donkeys who rejected the bull’s advances.
• The pair demonstrated selective preference for each other over other animals of their own species and both sexes, suggesting a strong social bond.
• The animals were separated after the study due to insufficient grass in their shared field, but researchers are currently attempting to reunite them to observe if the relationship continues.

Background

This story follows an earlier report from November 2, 2026, which first detailed the publication of the study in Current Biology. That initial coverage highlighted the reciprocal nature of the bond and the challenge it poses to assumptions that interspecies sexual contact is accidental. The current briefing expands on the specific behavioral details, the reaction of local herders, and the ongoing efforts to reunite the pair after their separation.

How outlets are covering it

CNN and VICE both emphasize the rarity and the 'romantic' or 'affectionate' nature of the bond, noting that the donkey actively encouraged the behavior. VICE highlights the 'cockblocking' behavior of the donkey toward other bulls, while CNN focuses on the scientific implications for understanding non-reproductive sexual behaviors. Mezha.net provides a more concise factual summary, focusing on the statistical data (51 mountings, 34 penetrations) and the logistical separation of the animals. All sources agree on the core findings but differ in emphasis: CNN and VICE highlight the emotional and social bond, while Mezha.net focuses on the observational data and the current status of the animals.

Why it matters

This case provides a systematically documented example of interspecies sexual behavior that is not driven by a lack of options, as both animals had access to other partners. It challenges the assumption that such behaviors are aberrant or accidental, suggesting instead that they may be part of a broader spectrum of animal social flexibility and bonding. The study highlights the need for more research into non-reproductive sexual behaviors in animals, which are often underreported or dismissed as unimportant.

What to watch

Researchers are currently in Ethiopia attempting to arrange a reunion between Achille and Patroclo after several months of separation. If successful, they plan to record the reunion to determine if the animals resume their previous interactions. The outcome will help determine whether the bond was a temporary phenomenon or a persistent relationship that can survive separation.