This protein helps birds traverse via magnetic field

Researchers have established that birds can sense the earth's magnetic field and use it to orient themselves. How this internal compass works, though, remains poorly understood.

Physicists at the University of Oxford are exploring one possible explanation: a magnetically sensitive protein called cryptochrome that mediates circadian rhythms in plants and animals. Blue or green light triggers electrons in the protein to produce pairs of radicals whose electron spins respond to magnetic fields.

Behavioral experiments have shown that even subtle disruptions to the magnetic field can impact birds' ability to navigate. In a study led by Henrik Mouritsen, in collaboration with Hore, robins were placed in wooden huts on campus at the University of Oldenburg in Germany. Without supplementary visual cues like the sun's position in the sky, the birds struggled to navigate.

They only regained their ability to orient themselves when the huts were covered in aluminum sheeting and electrically grounded, blocking external oscillating electromagnetic noise but not the earth's static magnetic field.

The researchers concluded that even low-level electromagnetic noise in the frequency range blocked by the aluminum screens, probably coming from AM radio signals and electronic equipment running in buildings, somehow interfered with the urban robins' magnetic orientation ability.

One explanation was that the electromagnetic noise has quantum-level effects on cryptochrome's performance. This would suggest that the radical pairs in cryptochrome preserve their quantum coherence for much longer than previously believed possible.

Such a finding could have broader implications for physicists hoping to extend coherence for more efficient quantum computing.