All the pigeons in the control group successfully navigated their way back to the aviary; those that received the injections lost their sense of direction and did not return home until the following day, when the sun was out. A follow-up experiment with the clodronate-treated pigeons under sunny conditions did not affect their homing ability because they were able to use solar cues. This suggests that pigeons use a combination of the sun’s orientation and magnetic sensing to navigate—and the latter is a previously unsuspected mechanism for magnetic perception in animals.

The authors think these results could also explain magnetoreception in bats and blind mole rats, which don’t have functioning cryptochromes or live in environments with little to no light. They might also apply to certain species of shark capable of swimming in straight lines over long distances—such as scalloped hammerhead sharks, which seem to orient themselves using seamounts found to have geomagnetic anomalies. “Beyond magneto reception, our findings contribute to a broader emerging concept: tissue-resident macrophages can function as peripheral sensory cells, providing direct, biologically meaningful feedback to the brain,” the authors concluded.

In an accompanying perspective, Simon Spiro of the Zoological Society of London and Hal Drakesmith of the University of Oxford noted some caveats. For instance, the iron-rich cells in the liver could have been due to the diet of captive pigeons, given that many zoo-housed animals have iron overloads. They also don’t think it’s yet clear that the liver is the best and most likely organ for sensing magnetic fields. It’s possible that doping the pigeons with clodronate also depleted macrophages located elsewhere in the body, skewing the histological results.

Spiro and Drakesmith cite a 2025 study, also published in Science, that used a different, more global methodology and suggested a different mechanism: Special cells within the pigeon forebrain encode magnetic information, thereby facilitating effective navigation. Both potential mechanisms do not require light stimulation, so it’s possible there could be two or more complementary processes at work to help pigeons navigate.

“Perhaps one process dominates for long-distance navigation, whereas another is used for more specific destination-finding, with both operating with different degrees of precision,” Spiro and Drakesmith concluded. “Indeed, it could be prudent to have more than one way of getting home in the dark.”

DOI: Science, 2026. 10.1126/science.ady2486  (About DOIs).