“Dead Duck Day” marks that time a scientist witnessed gay duck necrophilia

In his paper, Moeliker noted that the museum’s park has several water features, like ponds and ditches, favored by a wild population of mallard ducks numbering between 40 and 50 individuals at the time of the incident. His hypothesis is that the two ducks were in the midst of an aerial chase or “pursuit flight"—common mallard behavior—when the doomed duck hit the glass facade. “It is highly unlikely that the [other] drake was just passing by, saw the corpse, and started to rape it,” he wrote. One could quibble with the use of the word “rape” to describe the copulation Moeliker observed, but he wrote that given the deceased nature of the penetrated party, “the act was non-consensual anyhow.”

(a) Drake mallard duck in full breeding plumage next to a dead drake mallard, just after the latter collided with the new wing of the museum. (b) The same two ducks in flagrante delicto two minutes later.

Credit: C.W. Moeliker, 2001

Two male mallard ducks copulating would not actually be that surprising. Same-sex pairings have been recorded in some 450 different species, from flamingoes and bison to warthogs, beetles, and guppies. Female koalas sometimes mount other females, while male Amazon river dolphins have been known to penetrate each other’s blowholes. Lepidopterist W.J. Tennent, while diligently tracking Mazarine Blue butterflies in Morocco in 1987, spotted several males of the species mating with each other rather than with females of the species.

Nor is necrophilia limited to mallard ducks. A British naturalist named George Murray Levick traveled to Antarctica with the 1910-1913 Scott expedition and spent several months studying the breeding habits of a colony of Adelie penguins at Cape Adare. Levick was horrified to witness not just male penguins mating with other males but one young male Adelie penguin attempting to copulate with a dead female. Necrophilic behavior has also been observed in ground squirrels, New Zealand sea lions, rock doves, pilot whales, and crows, among other animals. Canadian biologist and linguist Bruce Bagemihl prefers to call this sort of thing “biological exuberance,” and his 2000 book with that title makes for a fascinating read for those curious to learn more.

Kees Moeliker: How a dead duck changed my life (2013).