The world's largest carnivorous bat is a hugger

With a metre wingspread, a wicked sting and a human face square come out of a creature feature, you'd be hard pressed to describe spectral bats as cute. But new research shows the apex predator is much more social — and cuddly — than we thought.

Published in PLOS One on Wednesday, researchers at the Museum of Natural History in Berlin documented complex social behaviours in a wild group of Vampyrum spectrum for the first time. 

Following a family of four, they found the bats hug each other when returning to the nest, share prey, co-parent their young, and sleep in tight huddles, among other behaviours.

Lead author Marisa Tietge said she came across a roost by chance in a hollow tree, while studying a different bat species in Guanacaste, Costa Rica. She installed a motion-activated camera in the base of the tree to capture two parents and two pups over three months.

One noteworthy behaviour was a "hug-like" greeting, Tietge said, where bats in the nest would leave their spot to welcome a family member back. 

"There's kind of a short wrapping of its wings around the other, like a short hug, then letting go, and then both or all of them go back to the main roosting spot," she said.

Tietge theorizes the hug helps them identify each other based on smell, and builds necessary social bonds for survival.

Spectral bats live in remote rainforests from Mexico to South America. Contrary to their Latin name, they do not drink blood. They hunt small birds, reptiles, mammals and sometimes smaller bat species. 

Spectral bats are monogamous — fewer than 20 bat species are — and parent their young together. The new research suggests that they raise their young for longer, with one grown pup staying in the nest alongside its newborn brother. 

The family Tiege captured on video was also seen roosting and sleeping tightly together in a "cuddle-ball." 

Spectral bat greets two others

Most bat species roost in large groups ranging from the dozens to the thousands. While there can be bodily contact, Tietge said it doesn't happen with the same individuals intentionally — or in balls.

The bats were seen leaving and returning to the nest together, which Tietge says challenges the previous idea that spectral bats are solitary foragers. 

The team also recorded the bats play-fighting with each other, chasing cockroaches around the nest without eating them, and messing around with the camera.

"They're very strong animals. They can bite through bones. They have a lot of power," said Tietge. "So they could have really destroyed them or really scratched them, but they didn't do it."

Rodrigo Medellín, an ecology professor at the National Autonomous University of Mexico who has studied bats for more than 50 years, said the research was not just surprising, but exciting.  "We have always suspected that particular species … had similar cooperative [behaviours] among themselves. But nobody had really documented all of that."

Tietge is now studying the family's diet and social vocalizations, and hopes to compare what she's found to other spectral bat roosts. 

While she doesn't want to reduce the bats to simply being "cute," she said these newfound behaviours might help soften people's perception of them.

Medellín said on top of their scary reputation, bats tend to be associated with evil and disease. "All of that I think comes from Bram Stoker's Dracula novel," he said. Medellín said he spent much of the COVID-19 pandemic defending bats from accusations that they were the cause of the illness.

"People can really see they're not these dangerous creatures that bite your head off right away or even drink your blood," said Tietge.

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