Science

Sick bats shown to socially distance

vampire bats
Vampire bats shown to reduce group contact when ill. Source: Oasalehm (via Wikimedia Commons)
Research shows sick bats reduce contact with other bats and move around the group less in a natural method of socially distancing.

By Holly Giles | Deputy Editor 

Social distancing is a term that has exploded into our vocabulary in the last year; most of us had never heard of it before, but it is not a normal part of life. Whilst it may be new to us, researchers at the Ohio State University have shown that vampire bats commonly social distance from the group whilst sick.

During the experiment the team injected 16 bats with a substance that induced an immune challenge (to simulate illness) and 15 with a placebo. The bats were then reintroduced to our group and three parameters were measured: “We focused on three measures of the sick bat’s behaviours: 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,” explained co-lead author Geral Carter. 

This was possible due to proximity sensors attached to the bats that take measure every few seconds to detect which bats are interacting together. Co-lead author, Simon Ripperger, explained the importance of these sensors: “The proximity sensors gave us an amazing new window into how the social behaviour of these bats changed from hour to how and even minute to minute during the course of the day and night, even whilst they are hidden in the darkness of a hollow tree”. The technology allowed the researchers to monitor the bat in conditions similar to their natural environment so their behaviour is not affected. 

They found that on average the sick bats associated with four fewer groupmates and spent less time interacting with each partner. The time any two bats spent together was lower if one of the bats was sick. 

Explaining the results Carter said:

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

A limitation to the study is that it did not use a real pathogen to cause disease which, depending on the pathogen, may change behaviour to make interactions more or less likely. While the study did not use an actual disease it is still important in showing how disease spread through the bat population, an important factor as they are a reservoir for zoonotic disease (animal diseases that then spread across to humans, for example COVID-19). 

Linking the results to COVID-19, Ripperger added:

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. 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.” 

This may be why social distancing feels so hard when we are well, but it is comforting to know that we are not alone in social distancing, nor is it a new phenomenon. 

 

Science and Technology Holly Giles

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