August 18, 2026

Written by Andrew Nguyen

Imagine you are dropped off in an unfamiliar city and need to find your way home – blindfolded. Humans typically rely on visual cues, like street signs or the position of the sun, to orient ourselves. Without those visual cues, how would you know which direction to go? It turns out that many animals, such as fish, sea turtles, seals, and birds, are able to navigate without visual cues by sensing the Earth’s magnetic fields, otherwise known as magnetoreception. This enables these animals to navigate home across long distances, even in low-visibility conditions like an overcast sky or in the dark. Recent work shows some surprising new findings about how pigeons use magnetoreception to help them navigate. 

From navigating the skies to the lab

Homing pigeons have long been of interest because of their unique ability to travel long distances, sometimes over a thousand miles, through rain or shine and still find their way home. Humans recognized this impressive skill and started to train them as domesticated messengers. Homing pigeons often carried messages to military groups, and eventually became used to carry news to journalists and newspapers¹. The history of humans training pigeons as messenger birds dates back thousands of years to ancient Egypt. Over time, technologies like the radio and telephones became more accessible and so pigeons became less employed as messengers and left abandoned by modern society leaving thousands of years of domestication to be forgotten. Despite being cast aside as messengers, scientists have taken pigeons in and employed them to help understand how these super navigators function.

Scientists have been studying how pigeons navigate for over a century, yet a lot of the underlying biology remains poorly understood. The current understanding of how pigeons navigate is called the map and compass model. 

First, the pigeons calculate where they are relative to a target location, usually their home, and create a mental map that helps to determine a direction home. Scientists think that pigeons build mental maps through sensory cues like smells in the wind or landmarks they can recognize like buildings or roads. 

Then, the pigeons rely on a compass to actually orient themselves in the right direction and ensure they stay on course as they navigate home². Scientists have confirmed that pigeons primarily use the sun as a compass on clearly visible days, when the position of the sun can be easily tracked by sight. But in less visible conditions, pigeons use a backup compass that is guided by magnetoreception instead of the sun, allowing them find their way home. However, how this magnetic compass works has been a big open question in the field. Scientists think that the sensory machinery enabling magnetoreception sits somewhere outside of the brain, but that magnetic information eventually gets relayed to the brain to successfully guide navigation. Based on recent studies, scientists may have narrowed down key magnetoreception hubs to two candidate areas: the ear or the liver.

Mapping the brain’s magnetic compass

Given that pigeons can use magnetoreception to navigate, scientists are interested in how the pigeon brain detects and responds to magnetic fields. To study magnetoreception in the pigeon brain, researchers generated magnetic fields that rotated around the birds and looked to see what areas of their brains were activated. Through these experiments, scientists observed that  brain regions that process sound became active during magnetic stimulation. When the team took a closer look at this brain region, they found unique cells in the ear canal that have specialized machinery for sensing magnetic signals. These ear cells send magnetic information to the brain, specifically a a hub for integrating sensory information called the mesopallium and the hippocampus, which is important for spatial orientation and navigation. While these data suggest that there are specialized cells in the ear that are magnetoreceptive and are connected to brain regions important for processing sensory information and navigating, there is no direct evidence of how manipulating the activity of the cells in a live pigeon changes how the birds can navigate. This incredible work highlights that specialized ear cells can detect magnetic fields, which might be an important part of the magnetic puzzle, but we still don’t know if they play a functional role in navigation. 

Liver immune cells: magnetic guides in the dark

Another prevailing theory of how magnetoreception works is that there are tiny crystals of magnetite iron inside the pigeon body that gets attracted to magnetic fields. Red blood cells are rich in iron that can respond to external magnetic fields. When red blood cells accumulate cellular damage, especially during aging, immune cells called macrophages engulf the iron-rich red blood cells and themselves can become reactive when exposed to external magnetic fields. Then, macrophages store this iron as a protein called ferritin. Researchers systematically looked at different organs of the pigeon to see which had strongest magnetic properties. To their surprise, the liver showed the strongest response to external magnetic fields⁴. When they took a closer look, the scientists confirmed the high presence of ferritin in the liver macrophages. Even with confirming liver macrophages respond to magnetic fields with stored iron-proteins, there is an open question of how liver macrophages transmit magnetic signals to the brain to influence navigation behavior. The team noticed that these iron-rich macrophages sit closeby nerve bundles that connect the liver to the brain and propose this is how magnetoreceptive liver macrophages communicate to the brain. 

To test whether these iron-rich macrophages truly do act as a magnetic compass in navigation, the researchers administered a drug that gets rid of macrophages. The researchers designed an experiment testing the ability of trained pigeons to navigate during cloudy, overcast conditions with or without iron-rich macrophages. Using GPS transmitters, they tracked each bird during low-visibility conditions and observed a striking result: pigeons depleted of macrophages were unable to successfully navigate home until visibility cleared. These results clearly show that the iron-rich macrophages are necessary for pigeon navigation by magnetic compass, but not other navigation (i.e. based on visual cues). The same birds were successfully able to navigate when it was sunny suggesting the drug did not have disorienting side effects. These findings represent a surprising and exciting new explanation for how magnetoreception may work in pigeons to guide navigation in the dark. 

Charting new territories

Magnetoreception has been known to exist in many different animal species, but how this sense works on a mechanistic level has been puzzling for a long time. These recent works describe two novel potential explanations of how magnetoreception may work in pigeons and allow them to navigate efficiently. Both the ear and liver are sensitive to magnetic field changes and there are compelling theories for how each of these areas may communicate with the brain to influence navigation behavior. While both areas can certainly respond to magnetic fields, the behavioral evidence for magnetic liver macrophages is compelling while the ear cells has yet to show functional, behavioral evidence. Iron-rich macrophages may be an attractive explanation for how many different animals, with varying exposure to light, may be able to sense magnetic fields. These exciting findings are a reminder about how complex biology is, that macrophage immune cells in the liver can function as modulators of a typically brain-centric behavior like navigation. Both the ear and liver models of sensing magnetic fields to guide navigation could exist and function independently of one another, demonstrating multiple regions that serve common goal of getting home in the dark. 

References

1. Pigeons through History https://www.rpra.org/about-rpra/pigeon-history/ 
2. Biro D Homing pigeons Current Biology, 28, R966-R967
3. Gregory C. Nordmann et al., A global screen for magnetically induced neuronal activity in the pigeon brain. Science 391, 1155-1160 (2026). DOI: 10.1126/science.aea6425
4. Clivia Lisowski et al., Homing pigeon navigation relies on superparamagnetic macrophages under overcast conditions. Science 392, 985-991 (2026). DOI:10.1126/science.ady2486

Claude Sonnet 5 was used to help with rewording. 

Cover photo by Colleen Sturtevant from Wikimedia Commons.