Bats have acoustic mental maps to navigate total darkness

Bats navigate effortlessly over vast distances using their natural GPS – echolocation. A recent study published in the journal Science has provided new insights into the extraordinary navigational capabilities of bats, and these abilities are more fascinating than we realized.

Echolocation – a technique not disrupted by darkness – is used by bats to avoid obstacles and orient themselves in the vastness of their environment.

A new dimension of bat navigation

By bouncing sound waves off objects and listening to the echoes, these nocturnal creatures can skillfully navigate their surroundings. Now, a new dimension has been added to their echolocating prowess.

The research was led by Iain Couzin’s group at the Max Planck Institute of Animal Behavior and the Cluster of Excellence Centre for the Advanced Study of Collective Behaviour at the University of Konstanz.

Through experiments, the experts found that bats can recognize their location even after displacement and utilize echolocation for map-based navigation over long distances.

Tracking a bat’s journey home

In Israel’s Hula Valley, a bat species named Kuhl’s pipistrelle (Pipistrellus kuhlii), weighing only six grams, was put to the test.

Across a few nights, 76 bats were relocated to various spots within a three-kilometer radius of their home. Each bat was equipped with an innovative lightweight reverse GPS tracking system, ATLAS, which offered high-resolution, real-time tracking.

Interestingly, even when solely dependent on echolocation, 95 percent of the bats found their way back home within mere minutes, demonstrating that bats are capable of navigating long distances using their localized, highly directional mode of sensing.

The researchers discovered that bats also employ vision, if available, for enhanced navigation.

Science of bat navigation

To investigate further, the research team generated a detailed map of the entire valley.

“We wanted to visualize what each bat experienced during flight and understand how they used acoustic information to navigate,” explained Xing Chen, an expert in the School of Zoology at Tel Aviv University, who was responsible for developing the valley’s reconstruction.

The model revealed that the bats have a preference for flying near areas with substantial “echoic entropy,” or regions that provide rich acoustic information.

The bats, during the localization phase, would meander around until a certain point – after which their flight was directed toward their destination.

This behavior clearly indicates that the bats possess some acoustic mental map of their home range. This allows them to identify distinctive environmental features such as a tree or a road, which they use as acoustic landmarks.

Mental maps and memory

Beyond their acute sensory perceptions, memory plays a crucial role in a bat’s ability to navigate efficiently. Researchers suggest that bats, like Kuhl’s pipistrelle, develop and refine a cognitive map of their environment over time.

This mental map is not a static image but a dynamic collection of experiences and stored acoustic information that aids in re-orientation after displacement.

Bats may rely on memory to access familiar routes or locations, integrating both real-time echolocation data and past experiences to optimize their flight paths.

This complex interplay between memory and sensory input enhances their adaptive navigation strategies, enabling them to thrive even in rapidly changing environments.

Future research directions

The findings of this study serve as a potential blueprint for developing advanced navigation systems. By understanding how bats combine echolocation with memory to navigate, scientists can draw parallels in designing autonomous vehicles or drones that require minimal visual input.

The high efficiency of bats in interpreting environmental acoustics presents opportunities to innovate and refine sonar-based technologies.

Future research might focus on exploring how bats adapt their echolocation strategies over different terrains or in varying atmospheric conditions, contributing further to our knowledge of sensory integration and its applications in technological advancements.

As our understanding deepens, the biosonar abilities of bats may inspire developments across various fields such as robotics, communication, and environmental monitoring.

Combining senses for navigation

Kuhl’s pipistrelles are capable of navigating over several kilometers using echolocation alone, but when vision is accessible, they optimize their navigational efficiency by combining both senses.

After being displaced, they strategize by first identifying their new location and then flying home, using distinctive acoustically marked environmental features as their landmarks.

Drawing parallels from such remarkable findings could enhance human navigation methods, particularly in situations where traditional GPS systems fail.

The study is published in the journal Science.

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