Last night, while watching Harry Potter and the Temple of Doom, I noticed a night scene where a cloud of bats swerved around to enter a narrow crevice in the ground. These bats were probably cgi, but don’t real bats do that too? I can see how a flock of birds could gyre and swerve past obstacles using light, by following the nearest wingtips, but how is that accomplished with each bat generating its own sound?
Are bat chirps individualized enough so that every bat can pick out its own voice from the cacophony, or is there some sort of hierarchy in which only certain bats echolocate when they’re swarming? Perhaps bats at the edges of a cloud let out a different style of chirp?
I’m not sure echolocating bats hunt in groups.
Whenever I’ve seen large numbers of bats in flight, they’ve never swarmed; they always are traveling in many different directions. It’s kind of looked like the choatic space battle scenes between fighters in the Return of the Jedi. My experience with bats is not extensive, however. So take that with a grain of salt.
Echolocation would not only be useful for hunting. A solo bat could use it to navigate around obstacles, as described.
However, ‘blind as a bat’ is not an appropriate aphorism - most bats have vision and can see pretty well in dim conditions, IIRC. Thus, they probably navigate by sight in flocks. WAG.
You might even have coplex behaviour where a lead bat is using echolocation, (and maybe a few flanking bats at different pitch,) and every other bat in the flock is following their lead, either by sight, or by following their cries sonically.
Bump for the nocturnal posters.
Bat swarm at Carlsbad
These bats may have enough light to see and flock outside the cavern, but how do they manage swarming flight inside, where it’s always dark?
Bats ‘recognise other’s voices’
The above is good for a few flying bats, but doesn’t yet adress how thousands of them manage to swarm out of a cave.
Well, this study is a little limited since it involved a bat distinguishing between the ‘voices’ of two other bats in an otherwise bat-free environment
Compared to flying in the middle of a swamp, this does not sounds like very much of a challenging task. Basically, you expect any mammal or bird to do this effortlessly.
Nevertheless, one should point out that:
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we humans perform pretty well in an equivalent situation, e.g. when we are chatting in a crowded bar. It’s not easy, but we can focus our attention on the voice of our neighbours. With a little bit of extrapolation, we can expect bats to dicriminate their own voice in rather noisy environment, especially since bat must have had quite some selective pressure on their ability to echolocate during their evolution.
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the ultrasound emissions as well as bat earing are directional:
This means that bat are not so much disturbed by the emissions of other bats flying in front of them (since these emissions are not directed toward them), nor by the bats behind them (since they don’t hear in this direction).