Pigeons sense the Earth's magnetic field—with their livers

Maja Mielke

Superparamagnetic cells in their livers help homing pigeons navigate on cloudy days.

It was an overcast day when a team of researchers released 34 homing pigeons into the sky. As part of a research project on bird navigation, the pigeons were supposed to return to their home base 19 km away. On that day, however, 18 of them failed to find their way home.

Photo by NATasha Nguyen on Unsplash

One day earlier, those 18 pigeons had received an injection of an agent that depleted a certain type of white blood cell in their liver. With their study, published this year in Science1, the scientists showed that these white blood cells—macrophages—appear to play a crucial role in the pigeons’ ability to use Earth’s magnetic field for navigation.

Macrophages contribute to the recycling machinery of an organism. As part of the innate immune system, they engulf and digest pathogens as well as some of an organism’s own material, such as aged or damaged red blood cells (erythrocytes).

The digestion of erythrocytes is what gives these macrophages a rather special trait. Erythrocytes carry iron. After engulfing them, macrophages store some of the iron in the form of dense packages called ferritin. These iron packages are what make the macrophages superparamagnetic. That means they can get magnetized by external magnetic fields—magnetic fields such as the geomagnetic field of planet Earth.

The exact mechanism by which these macrophages help homing pigeons determine magnetic direction is still not known. The researchers discovered that they are located near certain nerve fibers. This may indicate that these nerves transmit magnetic signals to the brain, where the information is processed and used for navigation.

Photo by Pavan Kumar Nagendla on Unsplash

You might wonder what happened to the 18 pigeons that got lost after being released. Don’t worry, they returned home safely after the sky cleared and cloud cover vanished. The Sun appears to be their primary navigational cue, serving as a visual compass. With the sun visible, homing pigeons navigate just fine without the paramagnetic superpower of their livers.

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  1. Lisowski, C., Quetting, M., Klaus, D., Lazarevski, L., Seep, L., Germer, M., … & Kurts, C. (2026). Homing pigeon navigation relies on superparamagnetic macrophages under overcast conditions. Science, 392(6801), 985-991. ↩︎