Birds can see Earth`s magnetic field
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Last Updated: Tuesday, July 13, 2010, 18:30
London: Birds can see the Earth's magnetic fields through their right eye and use that information to navigate effectively, German scientists have discovered.

Researchers at the Goethe-Universitat in Frankfurt found that a bird cannot navigate properly if its right eye is covered, but it won't have any problem if the left eye was covered instead.

Earlier studies had suggested that birds can sense magnetic fields and use them to navigate, particularly when migrating south for the winter.

But the latest research found the bird actually sees the magnetic fields with their right eye giving information to the left side of their brain.

The magnetic sensing overlaid over the normal vision with the magnetic fields creating light or dark shadings over what the bird usually sees.

"The shadings change as the bird turns its head, giving it a visual compass from the patterns of shading," the Daily Mail reported.

Scientists believe that the birds have molecules in their retina which shift into an active state when struck by blue light in which each molecule has an unpaired electron, creating a "radical pair".

"The presence of magnetic fields affects the time it takes for the radical pair molecules to revert to their inactive state.

"Both the visual and magnetic images involve variations in light and shade, but visual images tend to have sharp lines and edges, while the magnetic images have more gradual changes from light to dark," the report added. Researchers led by Katrin Stapput discovered that when this magnetic sense is distorted the patterns of light and dark make little sense because the bird cannot separate the information from the visual and magnetic images.

Stapput decided to test the theories by fitting robins with goggles that were covered with clear foil on one side and frosted foil on the other.

Both sides of the goggles were equally translucent, allowing 70 per cent of the light to get through, but on the frosted side the image was less clear. The birds were then kept in cages until it was time for them to migrate.

The birds were released into a funnel-shaped cage with its walls painted with fluid, which was scratched if the birds touched them. The results were that birds with no eye coverings, and birds with the left eye covered set off in a northerly direction as expected, while those with the right eye covered were disoriented and headed in random directions.


First Published: Tuesday, July 13, 2010, 18:30

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