If there's a term of the year for 2020, "social distancing" is in the running. But we're not the only ones keeping our distance. A study, published in Behavioral Ecology in October 2020, showed that vampire bats distance themselves from healthy bats when they are sick.
Previous research has shown similar findings with different animals in a lab setting, but to get the same results in the wild was "really cool," says Simon Ripperger, the study's lead author and postdoctoral researcher at The Ohio State University (OSU).
"There are [similar] reports from mice, for example, that act similar to vampire bats but also social insects and lobsters and all kinds of animals," Ripperger says. "It's really exciting to see that experiments from the lab and in the wild give the same results."
Researchers from OSU and the University of Texas at Austin traveled to Lamanai, Belize, in April 2018 where they found a hollow tree with a vampire bat colony. They blocked every exit from the tree but one and used a hand net to cover this exit.
The team captured 31 female vampire bats and injected 16 of them with a substance that made them feel sick but didn't give the bats a disease. The substance kicked in after three hours and lasted around six to 12 hours. They injected the other control group of bats with saline, as a placebo. Then, they glued miniature computer sensors to the backs of every bat before returning them back to their home.
"The sensors started collecting data on associations. All these tiny backpacks, they talk to each other, and we know 24/7 who has been near whom," Ripperger says. "Technology like this will help researchers get rich data sets and a deeper understanding of the consequences of such pathogen spreads in populations."
For three days, researchers tracked the bats' movements and social encounters in real time during the six-hour treatment period. The scientists found the sick bats spent 25 fewer minutes interacting and socialized with four fewer bats than their healthy group mates did during the treatment period. Also, the healthy bats had a 49 percent chance of associating with a healthy bat, while the sick bats only had a 35 percent chance of associating with another sick bat. While the control bats normally associated for 15 minutes an hour, the sick and healthy bats only associated for 10 minutes each hour.
"[We saw] increased sleep and reduced movements [in the sick] bats," Ripperger says. "Changes in behavior can really change how a pathogen spreads."