Last week, Cleo the four-year-old yellow Labrador retriever showed up on the doorstep of the home her family moved away from two years ago, reports Caitlin O'Kane for CBS News. As it turns out, Cleo traveled nearly 60 miles from her current home in Kansas to her old one in Missouri. Cleo is just one of many dogs who have made headlines for their homing instincts; in 1924, for example, a collie known as “Bobbie the Wonder Dog” traveled 2,800 miles in the dead of winter to be reunited with his people.
Now, scientists suggest these incredible feats of navigation are possible in part due to Earth’s geomagnetic field, according to a new study published in the journal eLife.
Researchers led by biologists Kateřina Benediktová and Hynek Burda of the Czech University of Life Sciences Department of Game Management and Wildlife Biology outfitted 27 hunting dogs representing 10 different breeds with GPS collars and action cameras, and tracked them in more than 600 excursions over the course of three years, Michael Thomsen reports for Daily Mail. The dogs were driven to a location, led on-leash into a forested area, and then released to run where they pleased. The team only focused on dogs that ventured at least 200 meters away from their owners.
But the researchers were more curious about the dogs’ return journeys than their destinations. When called back to their owners, the dogs used two different methods for finding their way back from an average of 1.1 kilometers (about .7 miles) away. About 60 percent of the dogs used their noses to follow their outbound route in reverse, a strategy known as “tracking,” while the other 30 percent opted to use a new route, found through a process called “scouting.”
According to the study authors, both tactics have merits and drawbacks, and that’s why dogs probably alternate between the two depending on the situation.
“While tracking may be safe, it is lengthy,” the authors write in the study. “Scouting enables taking shortcuts and might be faster but requires navigation capability and, because of possible errors, is risky.”
Data from the scouting dogs revealed that their navigation capability is related to a magnetic connection. All of the dogs who did not follow their outbound path began their return with a short “compass run,” a quick scan of about 20 meters along the Earth’s north-south geomagnetic axis, reports the Miami Herald’s Mitchell Willetts. Because they don’t have any familiar visual landmarks to use, and dense vegetation at the study sites made “visual piloting unreliable,” the compass run helps the dogs recalibrate their own position to better estimate their “homing” direction.
Whether the dogs are aware that they are tapping into the Earth’s magnetic field is unclear. Many dogs also poop along a north-south axis, and they certainly are not the only animals to use it as a tool. Chinook salmon have magnetoreceptors in their skin that help guide their epic journeys; foxes use magnetism to hone in on underground prey; and, sea turtles use it to find their beachside birthplaces.
Catherine Lohmann, a biologist at the University of North Carolina, Chapel Hill, who studies magnetoreception and navigation in such turtles tells Erik Stokstad at Science that the finding of the compass run, however, is a first in dogs. This newfound ability means that they can likely remember the direction they had been pointing when they started, and then use the magnetic compass to find the most efficient way home.
To learn more about how magneto-location works for the dogs, the study authors will begin a new experiment placing magnets on the dogs’ collars to find out if this disrupts their navigational skills.