Finding, catching and holding them captive is not difficult, Stockmaier said, “if you know where to get blood.” (His team gets everything it needs from local slaughterhouses.)
For the experiment, the scientists injected 18 female bats once with lipopolysaccharide (LPS), a compound that induces an immune response similar to a bacterial infection, without causing disease, or threat of infection, in the bat. It usually lasts between 24 and 48 hours. Females were used because they are more sociable than males, as they are more often engaged in grooming and community feeding and maintain ties to their young for long periods.
Later, the researchers injected the same group of female bats with saline as a control. In both cases, they removed the bats from the largest group, but within the hearing distance, and recorded and measured their calls.
They found that, on average, bats made 30 percent fewer calls, and 15 of 18 recorded fewer calls compared to the control group.
In another study, Stockmaier said, researchers found that bats injected with LPS produced symptoms of illness, slept more, moved less, and performed less grooming. He also noted that previous studies have shown that many similar animals require eight times more energy to call than not to call.
Thus, they concluded that bats are more likely to feel too bad to call, rather than intentionally suffocating as a naturally selected self-sacrifice to prevent transmission of pathogens to the general group.
Stockmaier regrets that “bats are getting a lot of bad press right now”, mainly because the new coronavirus, which causes Covid-19, is widely believed to originally have jumped out of horseshoe bats. He is quick to point out that it is a different species from vampire bats, and that they all offer something unique to study.
“I love bats,” he said. “I think they are fascinating animals.”
