Researchers led by Lisowski et al. injected pigeons with clodronate to deplete liver macrophages and then tested their homing ability. Control birds returned to the aviary within hours, while treated birds wandered until daylight revealed the sun. The experiment shows pigeons rely on both solar cues and a newly identified magnetic sensing system.

Electron microscopy revealed iron‑rich macrophages in pigeon liver tissue contacting nerve fibers, suggesting a direct route for magnetic information to the brain. The authors argue this peripheral sensor could explain magnetoreception in species lacking light‑dependent cryptochromes, such as bats, blind mole rats and certain sharks that navigate using geomagnetic anomalies.

Critics note the study may reflect iron overload from captive diets and question whether the liver is the primary magnetoreceptor. A 2025 Science paper identified forebrain cells encoding magnetic fields, indicating at least two independent mechanisms. Both pathways operate without light, hinting that pigeons switch between them depending on distance and precision needs.

The combined evidence reshapes how biologists view animal navigation, positioning tissue‑resident immune cells as sensory hubs. If future work confirms multiple magnetic detectors, engineers could mimic these biological antennas for low‑power orientation devices. For now, the pigeon study adds a tangible piece to the long‑standing mystery of how birds find home.