The Navigation of Pigeons Unlocked: They Sense Earth's Magnetic Field with Their Inner Ear.

According to ТСН: Researchers have found that pigeons perceive Earth's magnetic field not through their eyes or beak, as previously thought, but through their inner ear. This discovery is the result of a study by a team of scientists from Ludwig Maximilian University (LMU) in Munich, Germany.

The experiment involved 27 pigeons in a specially equipped laboratory. Initially, the magnetic field was completely turned off and then, for 72 minutes, a controlled signal of 150 microteslas was applied. This allowed researchers to determine which areas of the brain respond to the magnetic stimulus.

Brain Activity of Pigeons

Mapping the brain activity revealed a clear order of reactions. The vestibular nuclei — parts of the brainstem linked to the inner ear and balance control — were activated first. The signal then passed to the mesopallium, responsible for various sensory signals, and further to the hippocampus, which regulates spatial memory and navigation. No other significant changes in the brain were recorded, indicating a specific response.

To identify active neurons, researchers used the c-FOS marker — a gene activated in cells after stimulation. It is worth mentioning that these brain areas remained active even in complete darkness, which provides evidence against the theory of perceiving the magnetic field through light-sensitive cryptochrome proteins in the eyes.

Inner Ear as a Sensor

Additionally, researchers studied the cells of the inner ear. RNA sequencing showed that one type of hair cell in the semicircular canals contains many voltage-gated ion channels sensitive to small electrical changes that occur when fluid in the ear moves due to Earth's magnetic field.

This phenomenon is associated with electromagnetic induction: when a pigeon moves its head, the fluid in the semicircular canals shifts, and the intersection of the magnetic field generates microscopic electrical signals. Unlike balance signals that arise from mechanical bending, induction creates a separate electrical "channel," which the brain likely recognizes as magnetic information.

Researchers note that debates surrounding magnetoreception have been ongoing for decades. Previously, the primary theories were the role of cryptochromes in the retina and the presence of magnetite. Meanwhile, a 2012 study found that iron-containing structures in pigeons' beaks are immune cells rather than magnetic sensors, redirecting attention to the inner ear.

Study Limitations

Despite the impressive results, scientists admit that the recorded neuronal activity does not prove that pigeons necessarily use this mechanism in natural conditions. Laboratory magnetic fields differ from natural ones, and different species of animals may orient themselves in space differently.

However, the study's findings allow for a deeper understanding of how magnetic signals are transformed into nerve impulses. Researchers believe that the inner ear may play a more significant role in animal navigation than previously thought, and this mechanism may not be unique to pigeons but might also be characteristic of other species.

New discoveries that challenge old theories are not common in science. This research emphasizes the importance of the inner ear in developing navigation strategies in animals that have long been known to researchers, and now may gain new insights through these new research methods. It is possible that in the future, scientists will be able to observe similar mechanisms in other bird species or even in mammals.