Wild vampire bat. (Credit: Sherri and Brock Fenton/Behavioral Ecology)

“In the wild, vampire bats – which are highly social animals – keep their distance when they’re sick or living with sick groupmates. And it can be expected that they reduce the spread of disease as a result.”

COLUMBUS, Ohio — There’s still a mystery surrounding the origin of the coronavirus pandemic. Much of the focus has centered around bats and the Chinese region of Wuhan. While previous studies have revealed bats have certain immunities to the viruses they carry, it turns out they also know about social distancing too. Researchers at The Ohio State University say sick bats instinctively keep their distance from each other when they’re ill.

Social distancing during the COVID-19 pandemic, when we feel fine, doesn’t feel particularly normal. But when we’re sick, it’s common to withdraw a bit and stay in bed longer because we’re exhausted. And that means we’re likely to have fewer social encounters,” says co-lead author Simon Ripperger in a university release.

“That’s the same thing we were observing in this study: In the wild, vampire bats – which are highly social animals – keep their distance when they’re sick or living with sick groupmates. And it can be expected that they reduce the spread of disease as a result.”

Researchers captured 31 female common vampire bats living in a hollow tree in Belize. They injected 16 of them with a substance to make them feel sick. The formula didn’t actually give the bats any diseases however, and the remaining 15 received a saline placebo.

After returning the animals to their natural environment, with a custom-made “backpack” computer attached to their backs to monitor movement, scientists tracked how sick bats interacted with healthy neighbors and vice versa.

“We focused on three measures of the sick bats’ behaviors: how many other bats they encountered, how much total time they spent with others, and how well-connected they were to the whole social network,” explains Gerald Carter, an assistant professor of evolution, ecology, and organismal biology at Ohio State.

‘Sick bats groom also groom others less, make fewer contact calls’

On average, study authors find sick bats associated with four fewer groupmates than their healthy peers. They spent about 25 fewer minutes interacting with each partner and the time two bats spent together was shortest if the meeting involved a sick bat.

“One reason that the sick vampire bats encountered fewer groupmates is simply because they were lethargic and moved around less,” Carter says. “In captivity, we saw that sick bats also groom others less and make fewer contact calls. These simple changes in behavior can create social distance even without any cooperation or avoidance by healthy bats.”

Researchers suggest this behavior is likely common among other animals as well. They caution that certain behaviors will likely change based on the virus they’re exposed to. Carter adds some diseases may actually cause more interaction between infected patients.

“The proximity sensors gave us an amazing new window into how the social behavior of these bats changed from hour to hour and even minute to minute during the course of the day and night, even while they are hidden in the darkness of a hollow tree,” Ripperger explains.

The study appears in the journal Behavioral Ecology.

About Chris Melore

Chris Melore has been a writer, researcher, editor, and producer in the New York-area since 2006. He won a local Emmy award for his work in sports television in 2011.

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