Pulsed radiofrequency magnetic fields may disorient migratory birds, experiments suggest
Every year, millions of migratory birds travel between different geographical regions on Earth to find food, escape cold weather or reach safe environments to raise chicks. To determine which direction to fly, these birds rely on various types of sensory cues and information, including the magnetic field surrounding our planet, known as the geomagnetic field.
In a recent study, researchers from Saint Petersburg State University and the Zoological Institute of the Russian Academy of Sciences explored the possibility that pulsed radiofrequency magnetic fields could disorient migratory birds. The team focused on the magnetic compass system in birds, which is believed to be based on the protein cryptochrome inside their eyes.
The researchers proposed that the radical pair model, a leading explanation for how birds detect the Earth's magnetic field, may be more complex than previously thought. According to this model, cryptochrome molecules could serve as compass needles, and their operation is dependent on the presence of dim ambient light. When exposed to weak oscillating magnetic fields within the electron spin resonance (ESR) frequency range, these birds were found to become disoriented.
The researchers conducted experiments using pied flycatchers, a type of migratory songbird known to be sensitive to RF fields. They exposed the birds to weak RF oscillating magnetic fields with frequencies of 1.41 MHz and 1.5 MHz, as well as both unmodulated and amplitude-modulated signals. The amplitude-modulated signals were less powerful and more likely to affect the electron spins in cryptochrome, potentially allowing the birds to detect magnetic perturbations.
By comparing the effects of these different signals, the researchers aimed to test two alternative hypotheses: the radical pair model and the existence of a specific receptor for RF fields that detects the onset of a geomagnetic storm. The findings of this study could provide new insights into how migratory birds perceive magnetic fields and how they navigate across vast distances.
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