How ducks use magnetic field for landing

Zoologist Hynek Burda from Duisburg-Essen University in western Germany observed thousands of ducks and geese from Botswana to Canada. PICTURE: THOMAS HOLDER

Zoologist Hynek Burda from Duisburg-Essen University in western Germany observed thousands of ducks and geese from Botswana to Canada. PICTURE: THOMAS HOLDER

Published Aug 11, 2013

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Essen, Germany - It has long been known that migratory birds and homing pigeons use the earth's magnetic field for orientation, but new scientific research shows that ducks and geese also use more than sun and wind to find their way.

Zoologist Hynek Burda from Duisburg-Essen University in western Germany observed thousands of ducks and geese from Botswana to Canada in an effort to understand how the birds always managed perfect landings on water.

“Until now, the use of the earth's magnetic field for orientation has only been investigated with migratory birds and homing pigeons,” said Burda.

“Often, scientists wanted to find out how birds found their way when travelling over long distances. We have discovered a new function: landing on water.”

Burda's team observed water birds over a long period of time. Normally, geese and ducks use the sun and wind for orientation when they land on a lake. However, the scientists noticed that a flock of birds remained on course even in the absence of wind and sun. They did not deviate from their course or collide with one another.

“Accordingly, there has to be something else apart from the sun and wind that they all use for orientation. The birds also land perfectly on the water, which is extremely difficult to do,” he explained.

Altitude and trajectory on approach have to be perfect when landing on water. Birds can use trees, streets and even cars to estimate their own altitude when flying over land, something that is not possible when flying over water.

To compound the problem, geese and ducks fly extremely fast and are relatively heavy. All these factors have to be taken into account when the birds are landing on water.

How the birds use the earth's magnetic field for orientation has not been completely answered yet.

“They probably take it in through the retina,” explained Burda.

“You can perhaps imagine that a spot or point appears in its view as soon as the bird's head is pointed north. The bird then uses this dot as an orientation point.”

However, the idea of a spot appearing in the bird's eye-line is only speculation at this point, because magnetic alignment is something that happens in the brain and cannot be measured by observing eye movements under a microscope. - Sapa-dpa

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