I am surprised that the Vikings didn’t discover this first.  The Vikings did, after all, develop a sun compass for use on sunny days and used sunstones to find the direction of the sun when it was overcast.  One might have though that they would have perfected the defecating dog compass, as well.

Recently, researchers have documented that when dogs defecate they usually align their bodies along the magnetic north-south axis, not unlike the needle of a magnetic compass.

Dogs align themselves with Earth’s magnetic field when it comes time to poop

Czech and German researchers studied 70 dogs during 1,893 defecations and 5,582 urinations over the course of two years, and found that when the Earth’s magnetic field was stable the dogs chose to align themselves with it. When it was unstable, such as during a solar flare, the dogs would become confused.

Their findings, published in the journal Frontiers in Zoology, show that the dogs were sensitive to the polarity of the field, though not as much to its intensity.

Dogs on leashes, however, do not consistently align themselves as such, mainly doing so when they are free to choose. Researchers are yet to figure out why dogs exhibit this preference.