A new study has found that homing pigeons owe their remarkable ability to fly long distances not to their eyes, brains, or beaks, but to special cells in their livers.
The ability of pigeons to travel hundreds of kilometers and still find their way home has long puzzled scientists.
Previous theories suggested that these birds could detect Earth's magnetic fields using light-sensitive molecules in their eyes or tiny magnetic particles in their beaks.
However, none of these ideas have received convincing experimental support, despite decades of research.
New research shows the answer may lie in an unexpected place – the liver.
Scientists have discovered that homing pigeons can use specialized immune cells in their liver and spleen to detect the Earth's magnetic field, providing them with an internal navigation system.
These immune cells, called macrophages, were found to accumulate iron while simultaneously destroying old red blood cells.
According to a new study published in the journal Science , the accumulated iron gives these immune cells unique magnetic properties, including the ability to respond to the planet's magnetic field.
Scientists release a homing pigeon (Christian Ziegler/Max Planck Institute of Animal Behavior)
Researchers found that after removing the macrophages, pigeons had difficulty finding their way home, suggesting a previously unknown role for them in navigation.
«"What looks like 'intuition' in bird navigation may actually have a physiological basis," said Martin Wikelski, director of the Max Planck Institute for Animal Behavior in Germany.
«"If immune cells play a role in birds' direction finding, it will fundamentally change our understanding of navigation," Dr. Wikelski said.
While scientists have long known that migratory birds and homing pigeons use the Earth's magnetic field as a navigation tool, how exactly the animals detect this field remains one of the biggest mysteries in biology.
This new study found that the liver and spleen may play a key role in navigation, combining insights from immunology, physics and animal behavior.
In the study, the scientists examined several organs in homing pigeons that have previously been linked to the ability to sense magnetic fields, including the eyes, beak, and brain.
«"We had some indication that the liver and spleen have magnetic properties because they break down red blood cells and thus accumulate a lot of iron in the body," said Clivia Lisowski, another author of the study.
Pigeon liver tissue depicting iron-containing macrophages (blue) (Lisowski et al. (2026) Science)
Of all the tissues and organs analyzed, the liver had the highest iron concentration and demonstrated the strongest magnetic response.
Further studies confirmed that liver macrophages are responsible for these magnetic properties.
The scientists then tested whether macrophages actually influence navigation.
To do this, they extracted macrophages from the livers of pigeons that had been trained to return to their enclosure from locations more than 20 km away in Germany.
The researchers found that on cloudy days, when the sun was hidden, pigeons lacking macrophages became disoriented and had difficulty finding their way home.
However, on sunny days they were still able to return successfully, indicating that the birds use magnetic information along with solar cues to navigate in flight.
Then, using advanced microscopy techniques, the scientists assessed how information from the pigeons' livers was transmitted to the brain.
They found that iron-rich macrophages were located near nerve fibers, suggesting a possible pathway for transmitting magnetic information from the liver to the nervous system and ultimately to the brain.
«"These results provide the first concrete evidence of how the Earth's magnetic field can be sensed by the body and transmitted to the brain to control movement," said Dr. Lisowski.