Why Don’t Bats Get Disoriented By Each Other's Sonar?

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Contrary to popular clichés, bats are hardly blind. Yet, when it comes to getting around and locating food, vision takes a backseat to echolocation. By emitting high frequency sounds and listening to them bounce off various objects with their remarkably sensitive ears, bats are able to construct a mental picture of their environment. Amazing research about how bats locate bodies of water has recently shown that this strategy is, at least partially, instinctive:

However, many species are communally inclined, with as many as several hundred individuals occupying the same cave before taking off in massive swarms. With so many screeching at once, providing what would appear to be near-endless interference, a simple question emerges: Why don’t bats get distracted by each other’s cries?

It would appear that a variety of strategies exist. For instance, the call of the North and South American moustached bat is, according to biologist John D. Altringham, “so weak that other bats are very unlikely to hear it.” Because of the sound’s relative quietness, neighboring moustached bats simply ignore it and go on hunting undistracted by their kin.

Furthermore, Gareth Jones and Marc W. Holderid of the University of Bristol have observed that, in the lion’s share of species, most individuals have different call lengths to help them navigate different environments: When a bat flies in a wide open space, it will often use a lengthy vocalization, which will travel farther. Conversely, should the bat in question fly into a crowded environment, a series of short screeches, which can only bounce back a comparatively short distance, is preferable. Because the latter technique has a smaller range, fewer noises can interfere with the interpretation process—including the sonar of other bats. 

For more info on the subject of bat echolocation and its evolution, check out this story.