Grazing cattle and sleeping deer tend to align their bodies in the north-south direction of Earth's magnetic lines, European researchers said in a study in Tuesday's issue of Proceedings of the National Academy of Sciences.

Herdsmen and hunters have long known that cattle and sheep tend to face the same direction when grazing, and have believed they were simply positioning themselves according to prevailing winds or the sun's rays.

But Sabine Begall of the University of Duisburg-Essen in Germany and colleagues found that whether grazing or resting, these animals face either magnetic North or South.

They ruled out other reasons, such as wind or sun, for why grazing animals might orient themselves that way, since the direction of the wind and sun varied widely where the images were taken.

"The magnetic sense is virtually ubiquitous," said sensory biologist John Phillips of Virginia Polytechnic Institute in Blacksburg, who studied it in other animals.

The study employed 8,510 satellite images of cattle and deer herds derived from Google Earth from around the globe, including 308 pastures and plains.

The researchers also noted that humans and even whales are suspected of having an innate magnetic compass.

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