Scientists say the sick animals were more likely to keep to themselves.
Wild vampire bats socially distance when they're sick, according to a study published in the Behavioural Ecology journal.
Scientists had previously seen this behaviour in lab conditions, but wanted to find out if it happened in their natural habitat.
To conduct the study, researchers made half of a group of bats sick by injecting them with immune-challenging substance lipolysaccharide, and the other half with saline, before releasing them into 'natural conditions' and watching their behaviour over the next three days.
The researchers found the ill animals spent less time near others and associated with fewer group mates for around 48 hours.
Researchers Simon Ripperger, Sebastian Stockmaier and Gerald Carter said the "sickness-induced 'social distancing' can be important for modelling pathogen transmission as a social network changes over time".
The study was approved by the Institutional Animal Care and Use Committee and the American Museum of Natural History.
You can read the full study on the behaviour of Vampire bats here.
