The discovery of a new way for bats to mate has shed light on the unusual sexual behavior of this fascinating animal. While their oversized penises may seem disproportionate to their bodies, it turns out that they use them in a non-penetrative way. In fact, researchers have found that male bats use their large penis as an extra arm to push against the female’s tail membrane, allowing them to mate by contact. This behavior is similar to the ‘cloacal kiss’ of birds and marks the first time that non-penetrative sex has been documented in a mammal.

A team of international researchers made this discovery after observing bat mating behavior using cameras placed behind a grate that the bats could climb onto. They analyzed 97 mating acts from both a Dutch church and a Ukrainian rehabilitation center, noting that male bats grabbed their mates by the back of the neck and moved their pelvises (and fully erect penises) in a probing fashion until they made contact with the female’s vulva. After copulation, the researchers noted that the females’ abdomens appeared moist, suggesting the presence of semen. However, more research is needed to confirm that sperm was transferred during these supposed mating events.

The morphology of bat genitalia also plays a role in this unusual mating behavior. When erect, bats’ penises are about seven times longer and seven times wider than female vaginas, reaching about one-fifth the bats’ head-to-body length. Females also have unusually long cervixes, which could help them select and store sperm. Researchers speculate that bats may have evolved their oversized penises to push away female tail webbing, which they can use to avoid sexual intercourse.

This study adds an interesting twist to our understanding of bat sexual behavior and opens up new avenues for further research into this fascinating animal species.