For the first time, non-penetrative sex has been documented in a mammal—specifically, the serotonin bat. In a study published in Current Biology, researchers at the University of Lausanne, Switzerland discovered that male bats use their oversized penises to move the female’s tail sheath and maintain contact mating.
Bats’ penises are about seven times longer than their partners’ vaginas and have a heart-shaped head seven times wider than the vaginal opening, making penetration impossible. This makes it difficult to study bat mating behavior until now. Nicolas Fassel, lead author of the study, said: “We think it might be like a dog, where the penis gets soaked so it gets stuck, or maybe they just can’t get it in.”
The researchers observed genitalia during copulation using images from cameras placed behind a trellis that they could climb on. They analyzed a total of 97 couples from a Dutch church and a Ukrainian center. They also noted that the female’s abdomen appeared moist after copulation, indicating the presence of sperm. However, more studies are needed to confirm that sperm were transferred.
The researchers also characterized the genital morphology of serotine bats by measuring the erect penises of living specimens and performing necropsies on those that died. When erect, the penises of bats are about seven times longer and seven times wider than the vaginas of females of the same species. The researchers plan to study the mating behavior of these animals in more natural contexts and also study penile morphology and mating behavior in other bat species in the future.
In summary, this study revealed a never-before-documented mating behavior in mammals, shedding light on