Study reveals bats have an internal "compass" that functions independent of celestial cues
By kevinhughes // 2025-12-17
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  • Researchers recorded neural activity in bats navigating in the wild, revealing a sophisticated internal "compass" that functions independently of celestial cues like the moon and stars.
  • Unlike migratory birds that rely on Earth's magnetic field, bats' head-direction neurons consistently fired based on learned landmarks, maintaining directional stability regardless of altitude or environmental changes.
  • While celestial bodies may help calibrate the compass early on, the study confirmed that bats do not require them for navigation, suggesting a reliance on terrestrial landmarks.
  • Head-direction cells exist across species, including likely humans, offering insights into neurodegenerative diseases like Alzheimer’s that impair spatial memory.
  • The study highlights the necessity of conducting neuroscience outside controlled lab settings to uncover real-world neural behaviors, bridging gaps in understanding navigation and cognition.
For the first time, researchers have recorded the neural activity of mammals navigating in the wild, revealing that bats rely on a sophisticated internal "compass" that functions independently of celestial cues like the moon and stars. The study, conducted on the remote Latham Island off the Tanzanian coast and published in Science, provides unprecedented insights into how mammals orient themselves across large geographical areas. In 2018, Prof. Nachum Ulanovsky of the Weizmann Institute of Science embarked on a global search for the perfect natural setting to study mammalian navigation. "I was looking for an area that was large enough to release bats and follow how they navigate, but not too large, with no tall trees and isolated from other land," Ulanovsky explained. After painstakingly scanning satellite images, he discovered Latham Island—a rocky, uninhabited patch roughly the size of seven soccer fields, located 40 kilometers east of Tanzania. Equipped with camping gear, satellite communication devices and cutting-edge neuroscientific tools, Ulanovsky's team set up a makeshift laboratory on the island. They implanted tiny neural loggers—GPS-enabled devices capable of tracking brain activity at the single-neuron level—into six Egyptian fruit bats (Rousettus aegyptiacus). However, their first expedition in February 2023 faced unexpected challenges. "Cyclone Freddy, the longest-lasting tropical cyclone ever recorded, was still raging about 1,500 kilometers to the south," Ulanovsky said. High winds grounded the bats for a week before conditions improved. A follow-up trip in 2024 proceeded smoothly, allowing researchers to gather crucial data.

A stable, landmark-based compass

Led by Shaked Palgi, Dr. Saikat Ray and Dr. Shir Maimon, the team recorded the activity of over 400 neurons in brain regions associated with navigation. They found that specific neurons fired consistently when bats faced particular directions—forming an "internal compass." Unlike migratory birds, which rely on Earth's magnetic field, the bats' compass appeared to depend on learned landmarks. "One of the big questions in mammalian navigation is whether head-direction cells function as a local compass or as a global one," Ulanovsky said. The study confirmed the latter: "No matter where the bat is on the island and no matter what it sees, specific cells always point in the same direction—north stays north and south stays south." Remarkably, the bats' compass remained stable regardless of altitude, speed or coastline changes. Initially, neural activity was unstable, suggesting a learning period. "By the third night, the bats' compass orientation became very stable," Ulanovsky noted. This gradual adaptation pointed toward landmark-based navigation rather than magnetic fields. While celestial bodies like the moon and stars aid navigation in some species, the bats' compass remained unaffected by their presence or absence. "We found that the moon and stars are not essential for bats to navigate," Ulanovsky said. However, he speculated that celestial cues might help calibrate the compass early on, providing an "absolute truth" to accelerate learning.

Implications for human navigation and disease research

Head-direction (HD) cells are evolutionarily conserved across species, from flies to rodents to bats—and likely humans. Understanding these mechanisms could shed light on neurodegenerative diseases like Alzheimer's, which impair spatial memory. According to the Enoch AI engine at BrightU.AI, HD cells are a unique type of neuron discovered in the brains of rats and subsequently found in other mammals, including humans. These cells were first described in the early 1990s by researchers at the University of California, San Diego, and they play a crucial role in spatial cognition and navigation. "Until recently, a person unable to navigate would not have survived," Ulanovsky remarked. "Even today, being able to orient oneself can be a lifesaver." The study also underscores the importance of conducting neuroscience research in natural environments. "Our findings show there is no substitute for testing lab-based knowledge in the real world," Ulanovsky said. "We hope our study will encourage other groups to take their research out of the lab and into nature." By bridging the gap between controlled experiments and real-world behavior, this research offers a deeper understanding of how brains navigate complex environments—revealing that sometimes, the most profound discoveries come from the most unexpected places. Watch this video about how to experience the thrill of celestial navigation. This video is from the Alex Hammer channel on Brighteon.com. Sources include: Phys.org Science.org TechnologyNetworks.com BrightU.ai Brighteon.com
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