LEAVE a good-looking corpse, and your mates may mate with it. At least, that’s what happened with sand martins in Japan, which were filmed engaging in necrophilia.
In 2014, Naoki Tomita and Yasuko Iwami at the Yamashina Institute for Ornithology in Abiko saw a dead sand martin by the roadside. As they filmed, three males repeatedly mounted it. After 15 minutes, the researchers collected the body and identified it was a male. They have now published an article describing the incident – only the second paper describing such behaviour in birds (Ornithological Science, doi.org/bctv).
At least 30 cases of necrophilia have been reported in birds. Homosexual behaviour is common in birds, but in this case it was probably due to mistaken identity, as male and female sand martins look the same.
Tomita and Iwami think the event they witnessed occurred because the dead bird happened to end up in a pose resembling the female mating position. “We suggest that posture is an important trigger arousing male sex drive,” they write.
Kees Moeliker of the Natural History Museum Rotterdam, the Netherlands, agrees that the males were responding to the posture, rather than having a predilection for dead bodies. “It’s a mistake,” he says.
Mating with corpses has been observed in many kinds of animals, from spider mites to whales. While it may provide pleasure to some, it seems to have no benefit in terms of survival in most cases.
This article appeared in print under the headline “Male-on-male necrophilia filmed in birds for the first time”