Bats are silent when flying in groups

We still know that bats create a mischievous racket that helps them navigate in space. But it turns out they flapped their wings in a quiet environment when flying in flocks.

A new study shows that even in about a millionth of a second, bats have silently listened to the first baby while avoiding confusion because there are too many signals at the same time.

Sound navigation system

The directional bat through the same process as the locator system is called echolocation, in which they emit high-frequency calls and measure the distance to the surrounding objects by time. sound echoes.

Scientists wonder whether this exact method of calculation is eliminated when the bat in the herd makes sound, because it is difficult for bats to distinguish echoes from the sound itself. they emit among the echoes of other bats.

So Chen Chiu, Wei Xian and Cynthia Moss of the University of Maryland have recorded the sounds that bats emit when they fly in the lab. They found about 76% of the time at least one silence with a duration of 0.2 seconds.

Moss said: 'It doesn't sound like long to us. But in the perspective of bats, 0.2 seconds were long. They emit sounds with intervals of 0.02 to 0.05 seconds.

Silence breaks become more frequent as bats get closer together as well as the similarity of the sounds they emit.

Those who fly stealthily

According to Moss, scientists cannot be sure whether the bat's silence period is to avoid confusion and mistakenly fly into the object, but this seems like a reasonable conclusion.

Bats rely on spatial memory to navigate.(Photo: Jessica Nelson)

Replying to LiveScience, Moss said: 'It is a reasonable hypothesis. Maybe they are playing pouting together, they show some stealthy activities. Or maybe they're trying to save energy. But it seems that the most important reason is to minimize the noise interference phenomenon. This makes them more silent when the signal is more similar. '

Because bat's sound-based positioning method is very accurate, it is clear that the competing signal from a flying bat may damage the calculation of another. For example, if the bat confuses the echoing sound of another bat in its city even though this sound comes out a little earlier, it will think that the object that the sound is mistakenly echoes is located closer. real location.

Moss said: 'We think that they can use the sounds and echoes of the children with the piano to generalize, but for the extremely precise positioning activity needed to catch insects, the Bats need to know where they are when they make a sound '.

The researchers explained their findings on August 25 in the Proceedings of the National Academy of Sciences. The research was funded by the National Science Foundation, the National Institutes of Health, thesis scholarships William Hodos and Ann G. Wiley.

Air traffic control

If bat's silent method is really a way to control air traffic, it can answer the question that torches bat researchers.

Moss said: 'Bats sleep in the herd, and they fly out and follow the herds close together. So many people have wondered how they could fly out like that without being confused. Perhaps in such a situation, only some bats actually sound and others listen to those sounds. '

The behavior of bats varies from species to species, so scientists want to find out if there are other bats that control the sound in the same way as the big brown bats Eptesicus fuscus they studied.

Researchers also want to know how bats decide which sounds will emit sound and the order of silence to listen to them.

Moss said: 'We still don't understand this. Usually it is the last flying bat. The children in the herd easily listen to the sound when the sound is heard behind. There are many things we still don't know but this is the first important step to understand the interaction of bats in the flock. '