These bats are the only mammals known to mate more like birds
Male serotine bats’ penises are 7 times longer than the female’s vagina, so too big to penetrate
Male serotine bats (Eptesicus serotinus) have penises seven times longer than the vagina of a female of the same species, which means penetrative mating is impossible. Instead, the bats use a strategy common in birds but never seen before in mammals.
Alona Shulenko