One of the most intriguing abilities birds have is their skill at navigation. Even without maps or GPS, avian creatures seem to instinctively know where to go while they fly. While this ability has been somewhat conclusively linked to the Earth’s magnetic field, how they actually utilize it for navigational purposes has remained a mystery.
Until now, that is. Science News reports on new research that presents a strong case for exactly how birds can use magnetic fields for navigating during flight.
According to two different studies (one conducted on European robins and one on zebra finches), the mechanism by which birds navigate with magnetic fields might not be located in the beak as many predicted, but the eyes. The papers both identify Cry4, a special light-sensitive protein these birds have in their eyes’ retinas.
As a cryptochrome protein, Cry4 helps to regulate a bird’s circadian rhythm, otherwise known as the internal clock. However, based on observations made during the research, it might also react in some way to magnetic fields using principles of quantum mechanics.
In order to confirm these suspicions, the scientists observed the interactions between the Cry1, Cry2, and Cry4 proteins in the birds’ brains, muscles, and retinas to chart their activity throughout the day. While the former two proteins were seen to ebb and flow predictably throughout the day, Cry4 was shown to be constantly active, indicating it was continuously produced at all times.
Additionally, one study found that the robins happened to produce more Cry4 protein during migration season, further linking its appearance to the need for flight. That same study found that the highest levels of the protein were in an area of the eye exposed to large amounts of light, leading to the theory that it acts somewhat like a magnetic compass that birds can use to direct themselves in flight.
While the evidence is strong, it is not yet conclusive. Further study will need to be done before any major conclusions can be drawn, particularly study related to birds that lack the Cry4 protein. Even so, it does present several interesting ideas as to how birds can be so good at getting around, with compasses almost literally in their eyes being one way to finally explain it.
