It’s easy to be amazed at what a dog can smell – Covid-19, cancer, fear, time, the smell of its owner – but at least its sense of smell is a feeling we understand. As weak as our human sense of smell is compared to that of our dog, we still have the ability to detect chemical smells with our nose.
The idea of being able to sense the earth’s magnetic field is almost as incredible to me as the ability of Haley Joel Osment’s character in the film The sixth Sense to see dead people. I just can’t relate to it. Dogs aren’t the only animals with this ability, however. Birds, whales, dolphins, turtles, honeybees, and mole rats are some of the animals that share this widespread trait.
A 2013 study found that dogs preferred to eliminate with their bodies along the north-south axis of the Earth’s magnetic field. While it’s not clear why they do this, the study suggests that dogs can sense the magnetic field and that it affects their behavior. A few years later, in 2016, a study was published that may explain how dogs can perceive this field. Researchers found that dog eyes contain cryptochrome 1, a light-sensitive molecule that reacts to the magnetic field when stimulated by light at the same time.
This molecule plays a role in birds’ navigational skills and enables them to sense the magnetic field by activating the visual system. (Birds also sense the magnetic field through iron particles at the cellular level called magnetite, as do mole rats who live underground.) In mammals, cryptochrome 1 was found in only two of the 18 orders of mammals – carnivores (including canines, but excluding them.) Cats) and primates (including orangutans).
Now, in 2020, another study shows how sensing the Earth’s magnetic field affects dog behavior. In this study, researchers focused on hunting dogs as it is widely believed that they have amazing homing skills. They equipped 27 hunting dogs of 10 breeds with GPS trackers and collected data from a total of 622 daylight excursions at 62 locations. The dog drives lasted 30 to 90 minutes and were conducted in wooded areas away from buildings, power lines and roads. The routes they took back and forth were the subject of the study.
Many dogs followed their own scent back to the starting point using a method called “tracking” that was observed on 399 returns. On 233 excursions, the dogs returned to the starting point via a new route known as “scouting”. In 50 cases, dogs combined both strategies on a single return path.
Most of the dogs that returned through scouting began with a short run (about 20 m) along the north-south axis of the earth. They did this no matter which direction they had to go to get back to the starting point. The researchers hypothesized that the dogs perform this first “compass run” to orient themselves.
Although it was much more likely that scouting dogs’ routes began along a north-south axis, the direction of the start of the return route for tracking dogs was random. Another difference was that the scout dogs returned to their owners faster than the sniffer dogs. Gender and race did not affect the likelihood of using scouting versus tracking, nor did wind or sun.
Activity is observed in many animals along the north-south orientation of the compass axis. Such behavior enables animals to access a universal frame of reference that is so useful for navigation. While dogs share some of the same skills and mechanisms as migratory birds, marine mammals, and sea turtles, there is so much more to discover when it comes to the ability to search for dogs. What we know so far is that they have their own internal compasses, as people have been saying for ages.