According to foreign media reports, it is well known that bats use echolocation to locate prey in the dark, but... Is that really all there is to it? The scientists decided to get more details about the animal hunting process by equipping them with tiny wearable "computers." The study, conducted by a team at Aarhus University in Denmark, was conducted in a bat colony cave in Bulgaria from 2017 to the summer of 2019.
The researchers captured a total of 10 female rat ear bats, temporarily glued 3.5 grams of electronic tags to the fur on their backs, and then released them. After 2 to 14 days, the labels were taken off by hand when the bats were recaptured, or retrieved after they had fallen off on the floor of the cave.
Each unit contains a battery, a microprocessor, an inertial measurement unit (motion sensor) and a miniature ultrasonic microphone. As bats fly and hunt each night, motion sensors record their changing positions in three-dimensional space, while microphones record echolocation calls they make, as well as echoes from flying insect prey and other objects.
Bats can catch their prey hundreds of times a night, which means that the label does not hinder their ability to hunt. Interestingly, when they actively track insects, their echo-localized calls are far weaker than those simply used to locate their surroundings. In fact, the echo is described as "like a whisper".
Scientists believe that by using weaker calls, bats are better able to concentrate their sound in front of them than on their prey. In contrast, louder calls spread to both sides, producing interference echoes from different sources. It has also been noted that bats minimize these disturbances by remaining in open spaces.
"When bats are hunting, they maintain at least one prey detection distance from vegetation," said Professor Peter Teglberg Madsen, senior author of the study. "We think they did this to avoid faint prey echoes obscured by the huge echoes of vegetation." By constantly adjusting their flight patterns and sensory volume during hunting, bats simplify the information they need to process. ”
The research paper, led by Dr. Laura Stidsholt, was recently published in the journal Science Advances.