The church’s cameras captured a bat engaging in a sexual ritual.
The creatures were captured on surveillance cameras located in the dimly-lit areas of St Matthias church in Castenray, Netherlands.
The video is shot in monochrome, with animals intertwined and upside down, and the action occurring against a metal fence is frenzied rather than romantic.
However, the video may still lead to revisions in textbooks. Scientists suggest that the footage of serotine bats is the initial proof of any mammal engaging in sexual behavior without penetration. To put it simply, this means having sex without insertion.
Dr. Nicolas Fasel, a bat expert from the University of Lausanne, stated that it was a surprise. However, based on the evidence we have collected, it is evident that there was no penetration involved.
For many years, researchers have been puzzled by the reproductive behavior of serotine bats, specifically those belonging to the species Eptesicus serotinus. This is due to their physical anatomy, as the male bat has a significantly larger and uniquely shaped penis compared to the female’s vagina.
Researchers hypothesized two potential scenarios. The first was that the penis became engorged only upon entering the vagina, resulting in a “copulatory tie” that makes it difficult for dogs to separate during mating. The second possibility was that bats mated through physical contact, similar to the “cloacal kiss” observed in birds. However, this type of behavior had not been observed in mammals prior to this study.
In early 2020, Fasel received a message in his email inbox that sparked his latest project. The message was in Dutch and included the word “penis”, causing it to be marked as spam. However, Fasel’s attention was caught by the Latin name for the serotine bat. The sender, Jan Jeucken, is a bat monitor at St Matthias Church and the message contained intriguing footage.
After some time, Fasel received another message, this one coming from Ukraine. The researchers at a bat rehabilitation center in Kharkiv shared their own video footage which appeared to depict bats mating without any penetration. Overall, the team now had a total of 97 videos capturing the mating behavior – 93 from the Dutch church and four from the rehabilitation center.
The examination of the videos revealed that the male subjects did not participate in penetrative intercourse. Rather, they used their large penis as an additional limb to move the female’s tail membrane and reach the vulva. This action required some clumsiness, but typically lasted for about an hour and a maximum of 13 hours, as stated in their report published in Current Biology.
The researchers conducted further investigation by studying the physical structure of serotine bats, which involved observing live animals that exhibit erections when under anesthesia. This not only verified the notable size of their penises, but also discovered hairs on the heart-shaped head that may serve as a sensory mechanism during the search for the vulva.
Although the video does not provide conclusive evidence of non-penetrative sex in mammals, some female subjects exhibited fluid on their abdomens, indicating that males may have attempted to deposit sperm. The researchers plan to collect samples from females after mating and are constructing a specialized enclosure to film mating pairs from multiple perspectives.
Brock Fenton, a retired professor from the University of Western Ontario, remarked that the research reminded him of his own observations in the 1960s when he studied little brown bats in an old mine. He recalled that when he would separate mating pairs from the cave wall, he would often find the female bat covered in seminal fluid without any signs of penetration. Fenton stated, “The paper effectively shows that intromission does not appear to be occurring.”
Bat specialist Professor Paul Racey from the University of Exeter was doubtful about the observed penetrative sex in serotine bats. He questioned why they would engage in mating without intromission, risking the potential loss of semen. However, he acknowledged that with the recent discoveries about bat sexual behavior, he needed to keep an open mind.
According to the Ig Nobel prize-winning researcher, Prof Gareth Jones from the University of Bristol, evidence of fruit bats engaging in fellatio is convincing. However, confirming sperm in the vagina after would be required to prove successful copulation. Prof Jones also mentioned other surprising sexual behaviors of bats, such as males attracting females by urinating into wing sacs, males mating with torpid females, female relatives sharing sexual partners, and now, mating without intromission.