German scientists using satellite images posted online by the Google Earth software program have observed something that has escaped the notice of farmers, herders, and hunters for thousands of years: Cattle grazing or at rest tend to orient their bodies in a north-south direction just like a compass needle.
Studying photographs of 8,510 cattle in 308 herds from around the world, zoologists Sabine Begall and Hynek Burda of the University of Duisburg-Essen and their colleagues found that two out of every three animals in the pictures were oriented in a direction roughly pointing to magnetic north. The resolution of the images was not sufficient to tell which ends of the cows were pointing north, however.
Cows are known to align their bodies facing uphill, facing into a strong wind to minimize heat loss or broadside to the sun on cold mornings to absorb heat, but the fact that the pictures were taken at many locations, at different times of day and in generally calm weather minimized the effect of environmental factors, the researchers said.
Similar results were found in field studies of 2,974 red and roe deer in the Czech Republic, the researchers reported today in the Proceedings of the National Academy of Sciences. The researchers had been studying magnetism in smaller animals and were looking for a way to extend their work to larger species.
26 August 2008
Hey, if a cow can figure it out
The Los Angeles Times has an article about an unusual use of Google Earth photography: determining which way cows stand.
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