The study, led by Tel Aviv University Professor Yossi Yovel, is the first to demonstrate that bats are capable of orienting themselves across kilometers without relying on their sense of sight or other sensory aids.
By Pesach Benson, TPS
In a discovery that could inspire innovations in robotics and autonomous vehicles, Israeli scientists proved that bats can navigate over greater distances by echolocation than previously thought.
“While it’s well-known that bats use a natural sonar system to navigate by emitting sound waves and interpreting the returning echoes, previous research indicated that bats also rely on vision during flight,” researchers from Tel Aviv University and Tel Aviv’s Steinhardt Museum of Natural History said.
Echolocation is a biological sonar system used by certain animals, including bats, dolphins, and some birds, to navigate and locate objects in their environment by producing sound waves.
When these animals emit high-frequency sound waves, the waves travel through the air or water and bounce back after hitting objects.
The returning echoes provide information about the location, size, shape, and distance of objects, allowing the animal to “see” its surroundings using sound.
This approach could potentially enhance navigation systems in autonomous drones and underwater vehicles, offering efficient ways to interpret surroundings without relying on traditional cameras or GPS.
The study, led by Tel Aviv University Professor Yossi Yovel, is the first to demonstrate that bats are capable of orienting themselves across kilometers without relying on their sense of sight or other sensory aids.
The team’s findings were recently published in the peer-reviewed Science journal.
“In controlled laboratory settings, we’ve seen that bats can use echolocation alone to navigate within confined spaces.
However, echolocation typically detects objects only up to about 10 meters away, raising the question of whether bats can rely solely on this sense over open, natural terrains spanning many kilometers.”
To answer this question, Yovel and his team designed an extensive six-year study to test bats’ long-distance navigation abilities in Israel’s Hula Valley.
The team used a unique tracking system akin to GPS capable of following Kuhl’s pipistrelle bats (Pipistrellus kuhlii) — a tiny species weighing only six grams that is common in the Middle East, North Africa and parts of Europe.
The researchers began by capturing approximately 60 bats from a roost in the Hula Valley and transporting them about three kilometers away within their familiar environment.
To isolate the effects of echolocation, they temporarily impaired the bats’ other navigational senses.
Some bats were fitted with cloth strips over their eyes, effectively blinding them, while others underwent procedures to reduce their sense of smell and magnetic perception.
Despite these limitations, the bats demonstrated remarkable navigational capabilities, finding their way back to their roosts without difficulty.
“This finding alone was exciting, as it showed that bats could navigate home using only echolocation under real-world conditions,” said Dr. Aya Goldshtein, a researcher at Germany’s Max Planck Institute and a former student of Yovel who was involved in the research.
To understand how bats process environmental echoes to create a mental map, the researchers developed a computerized acoustic model of the bats’ natural surroundings in the Hula Valley.
This model allowed the scientists to simulate the echoes bats would experience in the environment, helping to shed light on the bats’ navigational decision-making.
According to Yovel, this model is based on a 3D map of the Hula Valley, which replicates the echoes that bats encounter during their flights.
“We found that bats actively choose routes rich in acoustic information, such as areas with dense vegetation, where echoes offer more detail than in open fields,” he explained.
“They avoid open spaces where the echoes provide less navigational data. Some regions produce distinct echoes, which become auditory landmarks for the bats, helping them maintain a mental map of the area.”
This map, composed of “sound landmarks,” enables bats to recognize their environment much like humans use visual landmarks to navigate familiar surroundings.
The study provides the first empirical evidence that bats construct such detailed acoustic maps in natural settings, which enhances our understanding of their complex sensory and cognitive abilities.
The findings challenge long-standing assumptions about the limits of echolocation.
“Bats have shown us that they are far more adaptable than we imagined,” said Yovel.
“Their ability to rely on a sophisticated system of sound-based navigation over vast distances not only reflects the remarkable evolution of their sensory abilities but may inspire new technologies in areas like robotics and autonomous navigation.”