Do you spend much time thinking about the way dogs position themselves while going to the bathroom? No? Huh, weird. Well, some scientists do, and it turns out Fido’s  preferred squatting position is much more calculated than just “wherever he feels like” or “dammit, not the living room AGAIN.” Instead, researchers have found that dogs align their bodies with Earth’s north-south axis while doing their business.

To test the theory, researchers from the Czech University of Life Sciences studied the body positions of 70 dogs across 37 breeds as they went to the toilet on walks. They recorded over 5,000 urinations and nearly 2,000 defecations which, as you might imagine, is an awful lot of pee and poop. What they found was that the dogs preferred a western orientation in the morning, and a more easterly one as the day wore on.

Time of day and position of the sun were ruled out as factors, as they studied the animals over several seasons when the sun’s position in the sky varied. The only other explanation, then, is Earth’s magnetic field, which has been shown to affect the behavior of other animals, such as birds.

“In this study, we provide the first clear and simply measurable evidence for influence of geomagnetic field variations on mammal behavior. Furthermore, it is the first demonstration of the effect of the shift of declination, which has to our knowledge never been investigated before,” the researchers said.

They also studied the Earth’s magnetic field over the same period of time, noting any changes. What they found was that even the smallest of disturbances could affect the way the dogs aligned themselves while eliminating. For example, during periods of solar flare, the dogs positions became significantly more random.

Despite the finding, the researchers admit they aren’t sure why the dogs behave the way they do. An estimated 50 total species on Earth are thought to use the Earth’s magnetic field, primarily for navigation. Birds, for example, are often observed migrating along the axis. That wouldn’t explain toe canine behavior, as there’s no reason to believe one pooping spot is magnetically favored over another.

“It is still enigmatic why the dogs do align at all, whether they do it ‘consciously’ … or whether its reception is controlled on the vegetative level (they ‘feel better/more comfortable or worse/less comfortable’ in a certain direction),” they wrote.

Other mammals, like cattle and deer, can be affected by the magnetic field. No word on whether they use it for pooping, however.