How do pigeons released kms away find their way home?:New research suggests they use magnetic sensors in their livers to navigate

For nearly a century, scientists have been trying to solve one of nature’s most fascinating mysteries: how do pigeons released hundreds of kilometres away manage to find their way home with astonishing accuracy? These birds can navigate across unfamiliar landscapes, through changing weather conditions, and often return to the exact location they started from.
Researchers have long known that pigeons use Earth’s magnetic field as a kind of natural GPS, but one crucial question remained unanswered: how do they actually detect it? Mystery that has confused scientists for decades Now, a new study published in Science suggests pigeons may use iron-rich immune cells in their livers to detect Earth’s magnetic field and navigate over long distances.
The discovery could help solve the long-standing mystery of magnetoreception, the ability of animals such as pigeons, sea turtles, whales, bats, and lobsters to sense Earth’s magnetic field for navigation. Although scientists have known about this ability for decades, exactly how it worked remained unclear until now. Martin Wikelski, Director at the Max Planck Institute of Animal Behavior in Germany and one of the study’s senior authors, said the mystery has persisted for almost a century. This has been one of the longest-standing mysteries in biology. Researchers knew the magnetic field must somehow be detected by the body and converted into signals the brain could understand. The problem was finding the biological structure responsible for doing that job.
Scientists looked everywhere except the liver Over the years, several theories emerged. One popular idea suggested birds could “see” magnetic fields through special light-sensitive molecules in their eyes. According to this theory, magnetic fields might subtly influence visual signals, helping birds determine direction. Another theory focused on the beak. Some scientists believed tiny magnetic particles hidden within beak tissue could act like microscopic compass needles. Researchers also investigated the inner ear and various parts of the brain. But after years of experiments, none of these explanations produced conclusive evidence. The search continued. Also read: Apple confirms iPhone, Mac and iPad prices will rise soon:AI chip shortage to drive cost hikes, Tim Cook calls it a ‘hundred-year flood’

A chance meeting sparked a new idea The breakthrough began more than ten years ago when Martin Wikelski met immunologist Christian Kurts at a scientific conference. Kurts was studying macrophages, immune cells best known for removing old red blood cells and helping defend the body against disease. As macrophages break down aging blood cells, they collect iron. Over time, some of these cells become packed with iron-containing particles. That observation sparked an unusual question. Could iron-rich immune cells somehow react to magnetic fields? The idea sounded unconventional, but it offered a completely new direction in the search for animals’ internal compass.
Examining every possible organ To investigate the theory, researchers examined tissues from several parts of pigeons’ bodies. The eyes, beak, brain, spleen and liver were all carefully analysed. Scientists used highly sensitive techniques known as ‘vibrating sample magnetometry’ and ‘magnetic cell separation’ to measure how strongly different tissues responded to magnetic fields.
The liver produced the strongest magnetic response by far. Researchers discovered large numbers of iron-rich macrophages clustered inside liver tissue. These cells contained iron oxide nanoparticles, making them highly responsive to magnetic forces. In simple terms, these immune cells behaved almost like tiny magnetic sensors. The discovery wasn’t enough — scientists needed proof Finding magnetic cells was interesting, but it didn’t prove they helped pigeons navigate. To test that possibility, researchers designed a real-world experiment. At the Max Planck Institute of Animal Behavior, pigeons were trained to return home from locations more than 20 kilometres away. Scientists then removed the liver macrophages believed to be responsible for magnetic sensing. The birds were released, and their journeys were tracked. Why cloudy days changed everything The pigeons’ performance depended heavily on the weather. On sunny days, birds that lacked the liver macrophages still managed to find their way home. However, on cloudy days, when the sun was hidden, the same birds became disoriented and struggled to navigate. Scientists believe pigeons use several navigation systems simultaneously. The sun acts as one source of information, while Earth’s magnetic field serves as another. When sunlight was unavailable, pigeons normally relied more heavily on magnetic cues. Without the iron-rich macrophages, that backup system appeared to fail. The findings strongly suggest that these liver cells play a key role in detecting magnetic information. Also read: ChatGPT can now set reminders and automate tasks for you: OpenAI introduces ‘Scheduled Tasks’ feature to monitor things

How does the liver communicate with the brain?
Researchers then turned to another question. Even if the liver can sense magnetic fields, how does the brain receive that information? Using electron microscopy, they found that the iron-rich macrophages sit extremely close to nerve fibres. This suggests the cells may pass magnetic information directly into the nervous system, which then carries the signal to the brain. Lisowski explained: These findings provide the first concrete evidence of how the Earth’s magnetic field can be perceived within the body and passed on to the brain to guide movement. This is one of the strongest pieces of evidence yet showing how magnetic sensing could physically work inside an animal. Longest-standing mystery The study does not answer every question about magnetoreception. Scientists still need to understand exactly how the brain interprets magnetic signals and converts them into directional information. After decades of searching the eyes, beak, and brain for birds’ hidden compass, researchers may finally have found it in one of the most unexpected places imaginable: the liver.