New study suggests that cows and at least two species of deer may be able to detect magnetic north
Roger Di Silvestro
WHEN RED and roe deer (European species) and domestic cattle across the globe graze or lie down to rest, they orient themselves along a north-south axis, according to a study published recently in the Proceedings of the National Academy of Sciences by zoologist Sabine Begall of Germany’s University of Duisburg-Essen and four colleagues from biological institutes in Czech Republic. In fact, the roe deer oriented their heads northward.
Biologists have known for years that some smaller mammals—a few rodent species and one bat—can detect magnetic north and that various birds, turtles and fish use magnetic north as a guidepost during migration. Begall and her associates decided to look for a similar sensitivity in large mammals.
Realizing that it would be difficult if not impossible to investigate the behavior with lab studies, the biologists looked for areas across the world where magnet north was a few degrees off of geographic north. They then used Google Earth images of 8,510 cattle in 308 grazing sites around the world and of 2,974 deer in more than 225 sites in the Czech Republic. All the animals, when eating or resting, faced either magnetic north or south. The study was done in a way that eliminated exposure to wind or sunlight as factors in the animals’ orientation.
Why the deer and cows oriented to magnetic north remains unknown.