In the summer of 1995, Kees Moeliker, a dutch researcher, was sitting behind his desk in the glass building of the Rotterdam Natural museum. Suddenly he was alerted by an unusual loud bang coming from the direction of the window. Outside the building, a male mallard (the common wild duck) was found dead, laying on its belly in the sand.
Next to the dead duck, another male mallard was present that forcibly picked the dead duck’s head for a few minutes after which it mounted the corpse and began forcefuly copulating with it. The male mallard raped the corpse almost continuously for 75 minutes(!), including two short breaks, before the author disturbed the cruel scene and secured the dead duck.
This bizarre observation is unique because homosexual necrophilic behaviour has never been described before. Interestingly, homosexuality is not very rare in ducks, with up to one in 10 duck couples being homosexual. Also occasionally necrophilia can be seen, but only with males trying to mount dead females. However the combination of the two makes it an extreme case, especially since the amorous male copulated with the dead male for over an hour!
The author explained that at the time of the collision with the window the two mallards were probably engaged in the common rape flight which is a normal reproductive strategy in mallards. Under the influence of raging hormones, the pursuing male was extremely aroused, further intensified by the lack of resistance of the fleeing (dead) male. In the author’s words:
When one died the other one just went for it and didn’t get any negative feedback—well, didn’t get any feedback.
This unusual observation of duck behaviour earned Moeliker the fantastic Ig Nobel prize for biology awarded for improbable research. Since then more observations of homosexual or necrophilic behaviour in birds were recorded, but the combination of the two has not been documented again.
Moeliker, C.W., 2001 – The first case of homosexual necrophilia in the mallard Anas platyrhynchos (Aves: Anatidae) – DEINSEA 8: 243-247 – full paper