Cow Compass

Cattle and deer might sense Earth's magnetic field

If you're lost and looking for north, you might have a better option than scouring the sides of trees for moss: New research indicates cows and deer tend to orient themselves toward the Earth's magnetic poles when grazing or resting.

Using Google Earth satellite imagery, German and Czech scientists looked at 8,510 domestic cows in 308 random pastures across six continents and photographed or studied the prints of 2,974 red and roe deer in the Czech Republic to determine body alignment. After eliminating reasons like wind or sun, they discovered that the animals tended to point their heads north or south. In the case of the Czech deer observed in the northern hemisphere, they usually pointed north.

The researchers discovered that in places where magnetic north differs from true north, the cows faced magnetic north, meaning they must have an internal sense of the Earth's magnetic field. Studies have shown other mammals, birds, fish, and even insects to be able to sense the magnetic field of the planet. They usually use it to navigate over long distances.

The scientists from the University of Duisburg–Essen in Germany who conducted the study aren't sure why cows and deer possess this ability, but they theorize that they might use it to map their surroundings and note basic landmarks.

Unlike their animal brethren, humans have never shown evidence for possessing an internal compass of any kind; watching my dad try to find his way through the grocery store helps prove this. Yet we continue to use humans in our mapping endeavors; have we overlooked the navigational possibilities of our silent, cud-chewing friends? Maybe it's time to give Ol' Bessie a chance.

— Ted Alvarez

Moo North: Cattle and Deer May Sense Earth's Magnetic Field (SciAm)