In 2013, Czech researchers studied 70 dogs across 37 breeds and found north-south alignment during defecation; the findings suggested dogs may sense Earth’s magnetic field

All dog owners have noticed their dogs circle over a grassy area for a seemingly longer-than-necessary amount of time before they take a seat. For most of us, it's a matter of sense of smell or instinct or just plain stubbornness. However, a 2013 study titled “Dogs are sensitive to small variations of the Earth’s magnetic field,” published in the journal Frontiers in Zoology, suggests that there could be another influence: that of Earth's magnetic field.

The study, conducted by Vlastimil Hart of the Czech Republic, included a total of 70 dogs from 37 breeds, and the scientists recorded almost 1,900 defecations and over 5,500 urinations during the two-year period. The central finding, which sparked interest beyond the Czech Republic, was that when the Earth's magnetic field was calm and stable, the dogs would regularly turn their bodies north-south whilst defecating and showed a strong statistical preference against turning east-west. The preference completely disappeared if the magnetic field was fluctuating. The study drew attention in part simply because it was peer-reviewed research that took canine magnetoreception seriously as a subject.

The experiment


The scientists didn't simply look at a handful of dogs and end their investigation there. Each dog's body orientation was recorded on site, using a handheld compass, while taking sex, age and breed effects into account, and was compared with real-time geomagnetic data from a German observatory. Dogs were released in open areas, away from roads, fences or power lines, in order to have no reason other than their own instincts (and possibly the field) determining their direction.

However, the pattern was observed only when the declination of the magnetic field, which can be described as the directional drift, was stable. This could account for the "messy and inconsistent results" of magnetoreception studies in other species, the study's authors wrote in their conclusion, noting that Earth's magnetic field is calm during only about 20 percent of the daylight period. Without taking the magnetic "weather" into account, you're missing the picture.

Dogs aren't alone in this club

It's not only dogs that have been thought to have an internal compass. A 2008 study titled “Magnetic alignment in grazing and resting cattle and deer,” published in the Proceedings of the National Academy of Sciences, analyzed Google Earth satellite images of 8,510 cattle across 308 pastures worldwide, along with field observations of nearly 3,000 red and roe deer at 241 locations in the Czech Republic, and found that both species tend to align north-south while grazing or resting. Foxes have been seen to launch their jumps more successfully north-east. Some migratory birds, sea turtles and even bacteria are known to have a sense of magnetic field and use it to navigate their path.

A little skepticism

The researchers concede that they still don't understand how dogs might be able to feel the magnetic field, nor why they would line up while they are going to the bathroom. In a published comment on the paper, Ludek Pekarek of the Czech Republic's National Institute of Public Health argued that the criteria the researchers used to classify "calm" magnetic field periods were not clearly justified, raising doubts about how strong the statistical evidence really was. Though even the scientists in a 2014 PBS NewsHour report described the behavior as "enigmatic.”

So, should you purchase a compass?

Probably not, but the study is a reminder that dogs may be picking up on something as old and intangible as Earth's magnetic field. With GPS pins and step tracking apps, it's a good reminder that there are some navigation systems that have been operating in the background all along. When your pooch takes the longest time to settle down into its bed next time, you may just be witnessing the compass setting itself.