The footage obtained with a hidden camera in the attic of a church in Castenray (Netherlands) has been decisive in this investigation into sexual behavior. This is not, however, a case typical of the gossip press, but quite the opposite, a certainly important scientific study.
Most of the images on which this study is based were obtained with the collaboration of Jan Jeucken, a retired Dutch amateur scientist passionate about the observation and study of bats.
Jan Jeucken's interest in the behavior of the garden bat (Eptesicus serotinus), a common species in much of Europe, added to the work of a scientific team made up of experts from the University of Lausanne (Switzerland), the Leibniz Institute, in Berlin (Germany) and the Ukrainian Bat Rehabilitation Center in Kharkiv (Ukraine) have discovered the first known case of a species of mammal that reproduces by copulation without penetration. The results of this research have been published in the journal Current Biology (November 20), including Jan Jeucken himself as the second signatory of the study.
The penises of garden bats, the study authors explain, are about seven times longer than the vaginas of their partners and have a heart-shaped head that is seven times wider than the vaginal opening. Both the size and shape of the penis would make post-erection penetration impossible. Researchers have found that, instead of functioning as a penetration organ, male garden bats use their large penises as an additional arm to push the female's tail sheath out of the way so they can mate by external contact. .
This sexual behavior is similar to the so-called cloacal kiss of many bird species.
"By chance, we had observed that these bats have disproportionately long penises, and we always wondered 'how does that work?'" says the study's first author, Nicolas Fasel of the University of Lausanne. "We thought that perhaps it was a sexual behavior similar to that of dogs, where the penis swells after penetration, or perhaps simply a relationship without penetration, but this type of copulation was not known until now ", indicates Professor Fasel.
The sexual behavior of bats has been very little studied and most previous observations of mating in these species were limited to images with the individuals facing away from the camera. In this new study, however, the researchers were able to observe the bats' genitals during copulation using images from cameras placed behind a grate that the bats could climb onto.
Nicolas Fasel collaborated with a bat rehabilitation center in Ukraine that opportunistically filmed mating pairs and with a bat enthusiast and amateur scientist, Jan Jeucker, who filmed hours of footage of a serotine bat in the attic of a church in the Netherlands. In total, the team analyzed 97 mating events: 93 from the Dutch church and four from the Ukrainian bat rehabilitation center.
Video recordings revealed that bats do not engage in penetrative sex. The researchers did not observe penetration at any time during the recorded mating events and noted that the erectile tissues of the penis enlarged before making contact with the vulva.
During mating, male bats grabbed their mates by the nape of the neck and moved their pelvises (and fully erect penises) in a probing fashion until they made contact with the female's vulva, at which point they remained still and embraced the females. females in a long embrace. On average, these interactions lasted less than 53 minutes, but the longest event lasted 12.7 hours.
After copulation, the researchers noted that the female bat's abdomen appeared moist, suggesting the presence of semen, but more research is needed to confirm that sperm was transferred during these supposed mating events.
The researchers also characterized the morphology of garden bat genitalia by measuring the erect penises of live bats that were captured as part of other research studies.
Their measurements showed that, when erect, manger bats' penises are about seven times longer and seven times wider than their females' vaginas, and about one-fifth the bats' head-to-body length. . These bats also have unusually long cervixes, which could help females select and store sperm.
Researchers speculate that bats may have evolved their oversized penises to push away female tail webbing, which females can use to avoid sexual intercourse.
"Bats use their tail membranes to fly and capture insects, and females also use them to cover their underparts to protect themselves from males," says Fasel, "but males can use these large penises to overcome the tail membrane. the tail and reach the vulva".
