Humans use facemasks to avoid infection, but the wrinkle-faced bats use it for a totally different reason. A new study published in the recent issue of the journal PLOS One reported that these bats hide behind a mask to seduce mates.
Researchers at the Costa Rica University found that when breeding time rolls around for male wrinkle-faced bats, they gather in groups and cover the lower half of their remarkably wrinkly faces with white-furred flaps of skin that resemble face masks. They then chirp ultrasonic songs through the masks while twiddling their wings. Scientists long suspected that the skin flap under the chins of these elusive bats had something to do with courtship, and researchers recently observed and documented this astonishing sight for the first time.
Wrinkle-faced bats live in forests "from Mexico throughout Central America to Venezuela and Trinidad and Tobago," and eat fruits and seeds. Their puckered face is more deeply creased than that of any other bat species. They are difficult to capture, and little is known about their behavior and habits in the wild.
According to a report published Monday on the Live Science website, it was a stroke of good luck when a pair of nature guides unexpectedly spotted several of the bats perching together in a tree hanging exposed and rather calm, during a night walk in a tropical forest in San Ramon, Costa Rica, on September 15, 2018. When lead author Bernal Rodríguez-Herrera saw photos of the rare bats and their unusual behavior, he immediately knew the nature guides had stumbled upon "an incredible find."
Herrera, director of the Center for Research in Biodiversity and Tropical Ecology at Costa Rica University, quickly assembled a team to observe and record the bats. They made 13 visits to the location over six weeks, between September 27 and October 31 that year. Every night, the bats assembled in the same spot between 6 p.m. and midnight local time. The team recorded video with an infrared-sensitive camera, and captured audio of the bats' ultrasonic songs and echolocation calls.
"As many as 30 male bats perched during the same night. They were masked, and through their masks, they sang "courtship songs" composed of echolocation sequences, trills, and whistles, punctuated by sequences of wing beats," Herrera explained.
"When a male successfully attracted a female companion, he immediately lowered his mask to mate with her. After they finished, the male immediately raised the mask again and resumed singing and beating his wings with the rest of the male bats," he added.