The yellow-winged bat is a vibrant species that comes in brilliant yellow, found flapping across countries in Africa. They’re one of five species of false vampire bats from the continent, but that’s not the only fake thing about them.
Yellow-winged bats (Lavia frons) are around 58–80 millimeters (2.3–3.1 inches) in size with the females typically a little larger than the males. This comes in handy when they’re with pup, as the females have the laborious task of flying around with their babies clinging on. A recent preprint revealed how carrying young can influence a female bat’s flying ability.
“Our results suggest that pregnancy has a significant effect on flight in female bats, with a particularly strong impact on achieving upward motion after emergence,” wrote the authors of the preprint that hasn’t yet undergone peer review. "However, the higher wingbeat rate per second recorded from bats flying during the pregnancy period implies that bats acclimate to such changes in body mass by altering their flight behaviors to sustain upward motion while pregnant.”
Not an easy task, then, but the female yellow-winged bat has a sneaky set of tools to make the process a little easier for her freeloading carry-on. Close to her anus sits a pair of false nipples that the pup uses as a way of clinging on.
The fake nipples mean the female can continue foraging and feeding while she carries her pup for several weeks after birth. It’s an unusual setup, but for the yellow-winged bat, it works.
“The mother-young attachment was secure: young Lavia held a 'false' (non-functional) inguinal nipple in its mouth, wrapped its legs around its mother's neck, and clutched the back of her neck with its feet,” wrote the authors of a 1987 observation of yellow-winged bat parental behavior.
“The young periodically released its hold on a false nipple and suckled from a pectoral nipple. Occasionally the young released its hold with its mouth, suddenly dropped down and hung pendant, grasping the mother's neck with its feet. From this position the young could stretch, groom, or flap its wings.”
Human babies might not cling to false nipples on their parents’ butts (thankfully), but we do get our own kind of false nipple. Known as supernumerary nipples, they affect around 6 percent of the popular and are present from birth, but often get mistaken for moles.
The other false thing about yellow-winged bats is their vampire status, being one of five false vampires found across Africa. Falling into the familiar Megadermatidae, the false vampires get their name for their superficial resemblance to true vampire bats, but crucially, they have a much broader diet that encompasses insects, small vertebrates, and fruits, rather than just chugging blood.
The yellow-winged bat looks more Pokémon than animal, so it seems fitting that it has a couple of special moves up its sleeve. Or anus, as it were.