Talk about animal magnetism: Cattle may have a built-in compass.
Somehow, cattle seem able to find north and south, say researchers who studied satellite photos of thousands of cows worldwide.
Most cattle that were grazing or resting tended to align their bodies north-south, a team of German and Czech researchers reports in today's issue of Proceedings of the National Academy of Sciences.
The finding held regardless of continent, according to the study led by Hynek Burda and Sabine Begall of the University of Duisburg-Essen in Germany.
“The magnetic field of the Earth has to be considered as a factor,” the scientists said.
The study sent Tina Hinchley, who with husband Duane runs a dairy farm in Cambridge, Wis., to look anew at an aerial photo taken of their farm a few years ago.
“Only about two-thirds were north-south,” she reported.
That's close to what researchers found in their look at 8,510 cattle in 308 pastures. Sixty percent to 70 percent of cattle were oriented north-south, which Begall termed a “highly significant deviation from random distribution.”
Hinchley said one factor to be considered is cow comfort.
“They don't like to get hot. Their body temperature is 102, and they are wearing black leather jackets, literally! If turning north-south would keep them cooler, they would stand that way.”
The team noted that in windy conditions cattle tend to face the wind, and have been known to seek the sun on cold days. But researchers said they were able to discount weather effects by analyzing clues, such as the position of the sun based on shadows.
“This is a surprising discovery,” said Kenneth Lohmann of the biology department at UNC Chapel Hill. “Nothing like this has been observed before in cattle or in any large animal.”
But Lohmann, who was not part of the research team, cautioned that “the study is based entirely on correlations. To demonstrate conclusively that cattle have a magnetic sense, some kind of experimental manipulation will eventually be needed.”
Joseph Kirschvink of the California Institute of Technology wondered whether fences could affect cattle orientation.
Passive alignment of animals to magnetic fields has been reported in honeybees and termites, he noted. It requires a special sensory organ to detect the magnetic field.