An international research team led by experts from the University of Bonn, University Hospital Bonn, and the Max Planck Institute for Animal Behavior has discovered supermagnetic macrophages in the livers of homing pigeons (Columba livia domestica). These specialized immune cells are believed to be crucial for navigation when solar cues are absent, unveiling a novel method of magnetic perception in animals.
Lisowski et al. employed various assays to reveal the presence of superparamagnetic macrophages in the livers of homing pigeons (Columba livia domestica). Image credit: Spainguitar101 / CC BY-SA 4.0.
The capability to navigate and maintain a trajectory towards a goal is vital for the survival of numerous species.
Field studies have indicated that diverse species depend on the Earth’s magnetic field for orientation, especially when visual indicators are lacking or inconsistent.
Birds serve as significant models to investigate this navigational ability. For instance, migratory songbirds are capable of sustaining a magnetically adjusted flight path over extensive distances, including at night or during overcast conditions.
Homing pigeons are assumed to utilize a mix of visual markers and environmental scents for positioning, alongside magnetic information.
To adhere to a designated path, birds employ either a solar or magnetic compass, both of which can function independently.
Unlike other vertebrate sensory mechanisms that feature distinct receptor organs, the processes underlying magnetic perception remain obscure and widely debated despite extensive research efforts.
“We never anticipated that immune cells could function as sensors for magnetic fields,” remarks Professor Christian Kurz from Bonn University Hospital.
“Our findings unveil an unprecedented mechanism of magnetic perception in animals.”
In this groundbreaking study, Professor Kurtz and colleagues have pinpointed a specialized population of macrophages in homing pigeon livers, exhibiting magnetic properties capable of responding to Earth’s geomagnetic field.
Upon the experimental removal of these cells, pigeons released under cloudy conditions completely lost their ability to navigate home.
In contrast, birds liberated on sunny days successfully returned even when macrophages were depleted, indicating that the liver’s magnetic system works optimally without visual cues.
Professor Martin Wikelski, director of the Max Planck Institute for Animal Behavior, states: “What might seem like ‘gut feeling’ in avian navigation potentially has a physical foundation.”
The macrophages in question are superparamagnetic, behaving like tiny magnets under low temperatures.
Researchers believe these cells acquire such properties through standard biological functions—breaking down aging red blood cells, accumulating iron released from hemoglobin, and storing it as ferritin.
Previously identified superparamagnetic macrophages in the spleens of mice and humans had not been associated with directional sensing until now.
In their experiment, the researchers trained 34 pigeons to navigate a 12-mile route from west to east.
The team then divided the birds, depleting macrophages in one group and subsequently releasing all under cloudy conditions.
Control birds successfully returned home within 70 minutes, while none of the macrophage-depleted pigeons made it back that day, instead drifting in random directions.
However, the same depleted birds were tested again under clear skies and managed to return home successfully.
Dr. Klivia Lisowski, a researcher at the University of Bonn and Bonn University Hospital, notes: “The liver and spleen’s magnetic characteristics arise from their role in red blood cell breakdown and iron storage.”
Dr. Ulf Wiedwald from the University of Duisburg-Essen adds: “The iron crystallizes with oxide nanoparticles, making the cells superparamagnetic and sensitive to magnetic fields.”
“Our strongest magnetic responses were detected in liver tissue.”
The authors suggest liver macrophages, located near nerve fibers, transmit geomagnetic signals to the brain via the vagus nerve, a recognized communication route linking peripheral organs to central processing.
They propose that multiple macrophages work collaboratively to sense geomagnetic fields, rather than a single cell independently detecting it.
If validated, this discovery could transform our understanding of magnetic reception beyond just pigeons.
“These findings offer the first tangible evidence of how the body’s perception of Earth’s magnetic field informs brain signals for movement,” concludes Dr. Lisowski.
“This study integrates established biological processes like iron metabolism with immune and nervous system communications, addressing fundamental questions about animal navigation.”
“Animal navigation remains one of nature’s most captivating phenomena,” Dr. Wikelski remarked.
“If immune cells play a role in avian direction sensing, it would significantly alter our comprehension of navigation.”
This important study was published in the Journal on May 28, 2026.
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Clivia Lisowski et al. 2026. Homing pigeon navigation relies on superparamagnetic macrophages under cloudy conditions. Science 392 (6801): 985-991; doi: 10.1126/science.ady2486
Source: www.sci.news
