Power Lines Upset Cows' Compass

Cows rest under power lines. i i

hide captionWhen near power lines, cows and deer position themselves facing random directions rather than in their usual magnetic north-south alignment.

K2D2vaca via Flickr
Cows rest under power lines.

When near power lines, cows and deer position themselves facing random directions rather than in their usual magnetic north-south alignment.

K2D2vaca via Flickr
Roe deer graze under power lines in the Czech Republic. i i

hide captionPower lines are known to locally change the Earth's magnetic field, and the researchers say the animals, like these Roe deer in the Czech Republic, may sense the magnetic fields and respond.

J. Cerveny
Roe deer graze under power lines in the Czech Republic.

Power lines are known to locally change the Earth's magnetic field, and the researchers say the animals, like these Roe deer in the Czech Republic, may sense the magnetic fields and respond.

J. Cerveny

High voltage power lines can interfere with the ability of cows and deer to respond normally to the Earth's magnetic field, according to a team of European researchers that has been studying these animals with the help of Google Earth.

"Under these power lines, the orientation of the animals is random, in all directions," says Hynek Burda of the University of Duisburg-Essen in Germany.

Last year, Burda and his colleagues made headlines when they first reported that cows seemed to have an internal magnetic compass.

By using Google Earth to study thousands of cows in pastures around the world, they discovered that resting or grazing cows tend to face magnetic north or south. The researchers also discovered a similar north-south orientation in resting deer.

Previously, the only mammals known to have magnetic compass orientation were a few species of bats and rodents.

The researcher's new follow-up study also used Google Earth, but this time to specifically look for animals under or near high voltage power lines.

Measuring Magnetic Impact

Burda says they were interested in these power lines because they are known to locally change the Earth's magnetic field.

They looked at 1,699 cattle under or near power lines in 153 locations in Belgium, Germany, Great Britain and The Netherlands. They also looked at 47 herds of deer near electricity pylons in the Czech Republic.

What they found is that resting and grazing cows and deer do not show the usual north-south body alignment when they're close to power lines. Instead, they position themselves in random directions.

Farther away from the power lines, cows and deer again begin to show the usual north-south alignment.

An Unexpected Twist

If the power lines were running east-west, however, the researchers noted that nearby animals tended to align their bodies in that direction, so Burda says "there is some interesting effect" with those particular lines.

The results of this study are reported in this week's issue of the Proceedings of the National Academy of Sciences. Burda says he thinks the evidence is compelling that these large mammals do in fact sense magnetic fields and respond.

"It is clear, if the animals change their behavior, there have to be some changes in the brain, on the cellular level, on the molecular level, and so on," Burda says. "That is what we want to study now."

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