Pigeons have an excellent homing ability. After being released in a remote location, they can find their way home on their own. Since ancient Roman times, people have recognized this ability of pigeons and used it to transmit information. Why do pigeons have this ability?
After being released in another location, pigeons usually turn around several times to orient themselves and then start heading in the generally correct direction. The key to finding their way home lies in having an accurate navigation system in their brains. Currently, there are three hypotheses about pigeons' navigation ability: solar navigation, geomagnetic navigation, and olfactory navigation, all of which have been verified to varying degrees in experiments.
When flying during the day, pigeons mainly use the position of the sun to orient themselves. On cloudy days or at night, they mainly rely on the Earth's magnetic field for navigation. Pigeons have magnetic substances in their upper beaks and brains, like a miniature compass, which can sense changes in the geomagnetic field. Narcotic experiments have shown that olfaction also plays an important role in pigeon navigation, but it cannot be proven that they can complete long-distance homing solely through olfaction.
Scientists from the University of Oxford have also found that pigeons can guide their flight by remembering roads and landmarks along the route. Overall, pigeons can use a variety of different methods to find their way home, and more reasons remain to be further discovered and verified.