Cutting edge researchMany animals behave in ways that show that they can use the Earth's magnetic fields to guide themselves. The most common examples of magnetic sensitivity are found in birds, which makes intuitive sense because birds often migrate over large distances. But now, for the first time, magnetic sensitivity has been shown in dogs, and the way that scientists discovered Fido's internal compass is a bit unusual.
Researchers gathered data over two years by following 70 different dogs, from 37 different breeds, as they... defecated and urinated. 1,893 poops, and 5,582 urinations in all. That's dedication to science!
The results show that "Dogs preferred to excrete with the body being aligned along the North–South axis under calm [magnetic field] conditions." If the magnetic field conditions are unstable, especially if there are changes in polarity, this "directional behavior" doesn't take place, which reinforces the hypothesis.
The "why" of it all is still nebulous:
It is still enigmatic why the dogs do align at all, whether they do it “consciously” (i.e., whether the magnetic field is sensorial perceived (the dogs “see”, “hear” or “smell” the compass direction or perceive it as a haptic stimulus) or whether its reception is controlled on the vegetative level (they “feel better/more comfortable or worse/less comfortable” in a certain direction). (source)
This study opens the door to more studies of magneto-sensitivity in animals (and humans?). Past studies might not have taken into account the magnetic field conditions, especially polarity, so their results might not be reliable. With this new methodology, maybe we'll find other animals that have evolved to use the Earth's magnetic field for various uses, some more useful than others -- birds going South during the winter, that's easy to understand, but pooping while looking, North? Not quite sure...