Birds Have Chemical Compass to Aid Navigation

Filed under Features

For decades scientists have been puzzling over an intriguing wildlife mystery: how is it that birds navigate? Each year thousands of these feathered creatures make massive journeys halfway around the globe – yet exactly how they find their way to their destinations each year just boggles the mind.

Until recently, there were two theories with regard to this amazing natural phenomenon in bird species. The first is that birds have tiny particles in their upper beaks. These particles, called magnetite, respond to shifts in the Earth’s magnetic field. The theory was credible and proved by research done with homing pigeons four years ago. The second theory, however, was still unsubstantiated. This theory revolved around the idea of a photochemical compass. It was thought that a protein, which was triggered by light through the bird’s eye, responded to magnetism thus providing a guiding compass that they could navigate by. This theory was considered to be weak since no one knew of a molecule that could respond to the Earth’s geomagnetic force so sensitively. However Oxford University has recently given weight to this concept by creating a compound that shows that this sort of chemical compass is possible.

Though this compound has thus far only been made and tested in a laboratory, it links the two biological pigments known as carotenoid and porphyrin with a carbon molecule known as fullerene. The process starts when a burst of light is used to excite the compound, resulting in the creation of ‘radical pairs’ of electrons. These each have a property called spin and research has shown that a magnetic field can cause the spins to become aligned. In theory, when the Earth’s gravity aligns these spins in the bird’s built-in compass, it most likely triggers a biochemical reaction that tells the bird what it needs to know about the magnetic field and helps direct it to its destination.

To scientists the new research is proof that the concept is possible. It also ties in nicely with previous research and it is thought likely that this is just one aspect of a complex navigational system that is commonly used by birds. However the debate is not over yet as it is still not known how the bird’s brain would be able to receive these informative signals and interpret them. Theories abound regarding this but have yet to be proven and properly understood.

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