The Mystery of Bat Echolocation Finally Unraveled

Proceedings of the National Academy of Sciences (PNAS), reveal an unprecedented behavioral and acoustic strategy that calls into question several theories accepted so far.

An aerial enigma finally clarified

The enigma has been intriguing for a long time. How, in the middle of thousands of fellows in tight flight, does a bat manage not to strike the others? The challenge seems insurmountable. Individuals emit each of the ultrasound to perceive their environment. But when they do it simultaneously, the echoes essential to orientation should be masked by neighboring cries. This jamming, called jammingwould theoretically make precise navigation impossible. However, the collisions are almost nonexistent. To understand this paradox, the research team has chosen to leave the laboratories to observe animals in natural conditions.

For two years, Aya Goldshtein, Omer Mazar and Yossi Yovel have equipped dozens of bats with location beacons and ultrasonic microphones. These devices made it possible to record the signals collected by animals in real time when leaving the cave. To compensate for the technical impossibility of capturing sounds inside the opening – Maximum density zone – the researchers completed the data with a sensorimotor modeling developed by Mazar.

Thanks to this faithful reconstruction of the collective theft, the researchers were able to access the sensory reality of a bat surrounded by congeners in a situation of extreme jamming. The study then reveals a capacity for behavioral adaptation hitherto unsuspected, based on ultra-rapid adjustments of the trajectory and the signals issued. An elegant, emerging, and above all extremely effective strategy.

Chaos at the exit of the cave for bats

The land chosen by researchers is not trivial. Located in the Hula valley, north of Israel, the Ein Mimon cave shelters exclusively male colonies each summer Rhinopoma microphyllum. This species can form dense and mobile swarms. During the night emergence, individuals rush outside the cave with a dizzying rate, up to 115 bats per second, through an opening of only three square meters.

The researchers equipped 96 bats with Atlas tags. This high -precision terrestrial geolocation system allows a frequency at a frequency of 1 to 2 Hz. Sixteen of these individuals also carried a miniature microphone capable of recording the ultrasonic signals emitted and perceived. The sounds were captured at 100,000 Hz, well beyond human hearing.

Only 40 meters from the cave, the microphones revealed a cacophony where 94 % of the useful echoes are masked by the cries of other bats. However, the collisions remain almost zero. Thanks to their sensorimotor model, scientists have shown that rapid dispersion – without rupture of the group – leads to an immediate drop in interference. At 300 meters, the average spacing between quadruple individuals, drastically reducing the risk of shuffle.

This collective behavior is not disorderly, but results from a precise compromise between maintaining the group and reduction of acoustic chaos. It shows that bats do not depend on an individual strategy, but on a shared spatial dynamic and adjusted in real time.

Adapt your voice to avoid the other

Faced with a saturated acoustic environment, bats are not content to move away from each other. They actively modify their way of emitting. “” The most important for a bat is to avoid the one right in front of it “Explains Omer Mazar. This prioritization of front detection conditions the entire vocal adaptation strategy.

Rather than trying to issue at a “free” moment or frequency, as the hypothesis of the Jamming Avoidance Responsebats adopt a more targeted solution. They emit shorter signals, less powerful, but at higher frequency. This drastically improves spatial precision on nearby objects. These modifications allow them to perceive the most relevant echoes, those of the immediate congeners. But while filtering the rest of the ambient noise.

Aya Goldshtein stresses that this response does not aim to reduce global interference, but to maintain a precise directional control, even in a context of massive jamming. It is an orientation strategy more than communication.

This behavior, described as CLUTTER Responsehad already been observed in certain species in a congested environment. Here, it applies to a dynamic and collective context, with very high density. It shows that the adaptation of bats is not a simple reaction to noise. It constitutes an active sensory response, integrated into their group movement mode.

Realistic simulation and minimum collision rate in bats

As mentioned earlier, to test their hypotheses in conditions that are impossible to observe directly, the researchers have designed a sensorimotor simulation reproducing the group flight of bats. Developed by Omer Mazar, it incorporates the known biological parameters of Rhinopoma microphyllum. There are sounds, flight speed, field of action of echoes, hearing threshold, density and distribution of individuals. The model simulates a flight over 1.3 kilometers with a realistic density of 25 to 115 bats per second.

Result: the average collision rate remains below 1.2 per individual, and the impacts are generally mild. In reality, animals start a avoidance maneuver even if the detection is late. This shows that a simple echolocation system, without centralized coordination or sophisticated strategy to avoid interruption, may be enough to navigate in a sound chaos … provided you are well adjusted.

The simulation also confirms that, even in a saturated environment, bats capture the most critical echoes-those of the congeners within a meter-thanks to their high intensity. By adding the vertical dimensions of real flight (absent from the model), as well as twilight vision or passive hearing, the real performance of bats is probably even better.

In the end, what some saw as an insurmountable acoustic headache may be just good management of promiscuity. Like what, in the animal kingdom, even in the middle of 10,000 noisy neighbors, you can keep your distance …

Source: A. Goldshtein, o. Mazar, l. Harten, e. Amichai, r. Assa, a. Levi, y. Orchan, s. Toledo, r. Nathan, & Y. Yovel, “Onboard Recordings Reveal Howuver Under Severe Acoustic Interference”, Proc. Natl. Acad. SCI. USA 122 (14) E2407810122. (2025).