For tips on flirting using a mask, take notes from nature experts: male bats with wrinkled faces. The first video of a wrinkled-faced sexual encounter shows a male covering his face with a flap of mask skin while cutting and then, at a strategic moment, loosening the mask.
Even the basics of how bats mate (whether a male distributes territory and advertises or females only buy from a multitude of exhibits) remain a mystery in more than 90 percent of the world's 1,400 bat species, says the mammologist Bernal Rodríguez-Herrera of the University of Costa Rica in San José. It was a stroke of luck when a tip from nature guides in 2018 led him to the first scientific observations on courtship in one of the most elusive bats in the tropics of the Western Hemisphere, the wrinkled-faced bat, Centurio senex.
Males, but not females, grow loose loose with mostly white skin below the chin that resembles a leggings pulled around the neck. A male can use skinny thumbs to pull the skin flap over his chin and mouth.
For the first time, investigators made a video about the mysterious masking of a masked young man from a wrinkled-faced bat (Centurio senex). With his white and natural natural skin mask in a concealed position, a male hangs in a Costa Rican jungle, ultrasonically drawing female attention. When a female throws herself, she drops the mask before they mate and then uses her thumbs to pull the flap of skin over her chin and mouth once the female has advanced. It’s still a puzzle: what about the mask that helps cut a male?
It doesn’t seem likely that only males need cold chin covers. Single-sex excesses often serve to show off, like peacock feathers fanned in competition for female favor (SN: 16/06/15). Now, a lucky first look at the wrinkled-faced courtship suggests that the masks somehow play a cutting competition, Rodriguez-Herrera and colleagues denounce on Nov. 11 in PLOS ONE.
For weeks, investigators watched as the bats gathered in the woods from six in the afternoon. until midnight, hung upside down at specific points with the masks on. Other bats occasionally beat briefly, but investigators did not know why.
It turned out that the hanging males were singing. Human hearing captures many nocturnal tropical sounds, such as the calls of frogs and owls, but not bats. However, bat recording instruments revealed a great song of ultrasonic bats. Sounds plunged into the range of human hearing only when an overflown visitor made a rapid intrusion. Males also “move the tips of their wings constantly,” he says. He may not know if the roaring wing brings any sound, but "we believe it's part of the courtship display."
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Seeing males gather in a specific place to sing suggests to Rodríguez-Herrera that the wrinkled nose species adopts a mating bar approach, hitherto rarely reported among bats. More scientifically known as lekking, males are grouped and displayed while females look for a gene contributor for the next generation. No help is offered to raise the resulting offspring.
For weeks, these male bats in Costa Rica spent the night rubbing their wings and singing backwards. The pale mask can function as a visual lure in low light or can play a role in the floating aromas, a romantic feature in some courtships of other bats. Or maybe the flap “helps sound the resonance,” Rodriguez-Herrera reflects. "We don't know."
What the researchers finally saw was a wrinkled nose pairing. A female landed on a male perch. The two clashed briefly. And when it was repositioned by intimate contact, the mask fell off.