Migratory birds have iron deposits in their beaks that act as a biological compass for navigation.
While birds do detect Earth's magnetic field for navigation, the mechanism is not simply iron deposits acting as a compass. Birds likely sense magnetism through specialised proteins in their eyes (cryptochromes) involving quantum entanglement effects. Some research suggested iron in beaks was involved, but more recent evidence points to the eye-based mechanism. The exact process remains an active area of research.
Reception
Sources
- Nature: Bird Magnetoreception PRIMARY
- PLoS Biology: Avian Navigation PRIMARY