internal compasses

Using satellite images on Google Earth, German scientists were able to see that all over the planet, cows stand with their bodies pointing to magnetic north.

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.

You have probably seen how cows will tend to face together in the same direction in a field, usually to face head on into a wind (reduces heat loss) or sideways to the sun (maximize heat gain), but because the photos on Google Earth are so widespread and taken in generally good weather, it appears that cows have a "default setting" of north-south orientation when local conditions don't override it.