For many years, bats have fascinated us with their remarkable ability to navigate in the dark using echolocation—emitting sound waves and decoding the returning echoes—similar to the sonar technology used in submarines. While echolocation has until now been regarded as a short-distance navigation tool, a new study reveals that bats can use it to orient themselves over kilometer-scale distances, relying on an internal “acoustic map” of their surroundings even when deprived of other senses such as vision, magnetic sensing, and smell.

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Navigation is a complex task for any animal, and bats face unique challenges because most of them are nocturnal. Their echolocation system is inherently directional and short-ranged, usually effective only up to several tens of meters, comparable to the beam of a small flashlight. This limitation has raised an interesting question: can bats use this sense to navigate over long distances?

Previous studies [1, 2, 3] have shown that bats can employ various navigation strategies, such as path integration relative to the starting point, a cognitive map, i.e., the ability to imagine a three-dimensional space and navigate within it, following a specific route, visual cues, and even the Earth’s magnetic field. Yet the question of whether bats can rely solely on echolocation for long-distance navigation remained unanswered.

In a new study [4] published in the journal Science, led by Dr. Aya Goldshtein and Prof. Iain Couzin from the Max Planck Institute and the University of Konstanz, together with Prof. Yossi Yovel from Tel Aviv University, the researchers found evidence that echolocating bats can navigate several kilometers using echolocation alone.

The research team conducted an experiment on the Kuhl’s pipistrelle (Pipistrellus kuhlii), a tiny insect-eating bat weighing about six grams that is very common in Israel and Europe. This species is known for its excellent echolocation abilities, its limited reliance on vision, and its relatively low-altitude flight that allows it to sense the ground through echolocation. The bats were captured near their roost in the Hula Valley and transported to one of two points about three kilometers away—still within their habitat.

The bats were divided into three experimental groups and one control group. In all experimental groups the researchers temporarily and reversibly blocked one or more of the bats’ senses:

First group—vision prevented: blindfolded bats.

Second group—vision and magnetism prevented: blindfolded bats with their magnetic sense disrupted.

Third group—vision, magnetism, and smell prevented: blindfolded bats with their magnetic sense disrupted and their sense of smell neutralized.

Control group: bats whose senses were not interfered with.

Seventy-six bats were equipped with a tiny tracking device that allowed the researchers to monitor their movements with high accuracy almost in real time. About 95 % of the bats successfully returned to their roost or to a known feeding site within minutes, regardless of sensory interference. Even bats deprived of vision, magnetic sense, and smell managed to find their way home, apparently relying solely on echolocation. However, the control bats navigated best: sighted bats flew faster and followed shorter, more direct paths toward their roosts than blind bats, enabling them to reach their destination in a shorter period of time. In other words, echolocation alone is sufficient for navigation over these distances, but combining it with vision improves efficiency.

After release at the distant points, bats from all groups initially flew in random directions but soon switched to a direct course toward their destination. This behavior indicates that the bats quickly identified their location and the relative direction and distance of their target. This finding is particularly significant for the third group, which could use only their sense of hearing, as all other relevant navigation senses were temporarily blocked; they perceived only their immediate surroundings and could not sense the destination from the release site. Their navigation implies the existence of a cognitive map based on acoustic information.

To understand how bats might build such a map in the brain and use it, the researchers employed advanced computational techniques to create a three-dimensional model of the terrain and of the echo returns the bat experiences along its flight path.

The researchers found that different environments generate unique acoustic signatures. For example, complex surroundings such as orchards and populated areas provide rich acoustic information that can serve as landmarks for the bats. It appears that the bats used these features to make navigation decisions, especially as they were deciphering their position after release and in instances when they had to change direction. In addition, the researchers applied advanced statistical measures to assess how distinguishable various acoustic environments were. The resulting values showed that certain areas had unique acoustic profiles that enabled bats to recognize specific locations within their habitat and navigate accordingly. In other words, these profiles allow bats to distinguish between a plowed field and an orchard, and in some cases even to identify a particular orchard.

The study provides the first piece of evidence that bats can use echolocation alone for long-distance navigation while constructing and employing an acoustic cognitive map. It challenges previous assumptions about the limitations of echolocation and reveals the complex navigation strategies bats use. Understanding how bats navigate also has broader implications: such research can spawn biologically inspired technologies, including advanced sonar and drone navigation systems. Moreover, this remarkable ability highlights the cognitive capacities of animals with small brains and offers insights into the evolution of navigation and memory in the animal kingdom.

The researchers suggest that future studies should examine how bats develop their acoustic maps over time and whether they can adapt to environmental changes. They also aim to explore how bats integrate information from multiple senses to optimize their navigation strategies.

Thank you to Dr. Goldshtein for her advice in writing this article.

*Disclosure: Yomiran studies bats in Prof. Yossi Yovel’s lab at Tel Aviv University.

Photo: Eran Amichai

Hebrew editing: Galia Halevy-Sadeh
English editing: Elee Shimshoni

References:

1. Navigate like a bat
2. An article about how bats hunt insect swarms
3. The bats’ internal GPS
4. The article in Science