These Bats Mask Up to Woo Mates

Seduction sometimes requires leaving something up to the imagination, and for male wrinkle-faced bats, that means donning a mask during courtship. New research, published last week in the journal PLoS ONE, documents this unique behavior and the mating that follows for the first time, reports Katherine J. Wu for the New York Times.

This aptly named, fruit-eating bat has a mug covered in ridges and folds of skin of nearly unparalleled complexity even in the world of bats, which includes some of the strangest—and cutest—faces around. But when it comes time to reproduce, male wrinkle-faced bats pull furry flaps up and over their faces, leaving only their eyes exposed, while they try to attract females. When the wooing’s done, the bats amorously jostle and the male finally removes his mask to mate, reports Susan Milius for Science News.

The never-before-recorded behavior came to the researchers’ attention in 2018 when two nature guides spotted a group of the unique-looking bats hanging out near a trail in San Ramon, Costa Rica, according to a statement. News of the sighting worked its way to the co-authors of the new paper, who quickly sprang into action to catch a glimpse of this rare species that September.

“This was an incredibly lucky encounter with these rarely observed ‘masked seducers,’” says Marco Tschapka, a research associate at the Smithsonian Tropical Research Institute from the University of Ulm and co-author of the research, in the statement.

“Not only is this a rare bat species that a lot of bat researchers would love to have on their life lists, these bats were doing something that no one had ever seen before,” adds Bernal Rodríguez-Herrera, a mammalogist at the University of Costa Rica in San José and the paper’s lead author.

The researchers spent 13 nights in the Costa Rican forest observing the bats from dusk til midnight, according to Science News. In certain places, the researchers found rows of male wrinkle-faced bats convening to dangle from branches with their faces covered by a furry fold of fur-covered skin that only males of the species possess.

It turned out these masked males were singing—belting out a series of chirps and whistles—to try to court females, reports Mindy Weisberger for Live Science. If a female flew in for a closer look, the researchers observed the successful males beating their wings and producing a loud whistle that dips down into the frequencies of sound humans can hear, per a statement. Just before and during copulation, the coupled-up male dropped his mask, only to raise it again and resume singing when the affair was over, about 30 seconds later, per the Times.

The team captured infrared video and ultrasonic audio of as many as 30 bats a night, from a total of 53 perches, but only one instance of mating.

One question posed by the findings is whether these wrinkle-faced bats are doing something called lekking. A lek is a type of courtship in which a panel of males will assemble in what’s termed a mating arena to posture, sing or otherwise display their manly wares in hopes of winning the right to mix their genes with female onlookers. If the wrinkled-face bats are indeed lekking, it would be an even rarer finding.

Though the new paper’s observations are compelling enough to suggest the possibility of lekking, Mariana Muñoz Romo, a bat biologist at the Smithsonian Tropical Research Institute who was not involved in the study, is holding out for more evidence, telling the Times she prefers to be cautious.

But Cory Toth, a Canadian wildlife biologist who has studied lekking in bats but wasn’t involved in the study, tells the Times he’s “not surprised that we’re finding another bat that’s a potential lek breeder.”

As for what role the masks play in making these male bats more attractive, Rodríguez-Herre tells Science News we simply “do not know.” While it’s not clear how the females are weighing their wrinkle-faced suitors against one another, the researchers speculate that the skin flap masks might serve to modulate the males’ songs or even waft alluring scents.

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