Naturalist Notes

It’s not intuitive to think of a four legged mammal as an aerial hunter. Yet, foxes clearly depend on their ability to take prey from the air. Watching a fox hunt is spectacular but the suspense can be almost unbearable! Their spellbinding leaps appear to happen like magic – how does the fox know exactly where the mouse they are hunting might be? They seem to have a sixth sense. Well… It turns out they might.

Researchers studying foxes in the Czech Republic found that a fox’s leaps are much more likely to result in dinner if the fox is oriented in a Northeasterly or Southwesterly direction. Why? It seems foxes are using magnetic inputs in addition to sound to accurately determine their distance from their prey. This is particularly interesting because other documented cases of animals using magnetic information do so to determine direction, not distance.

To imagine this, it’s helpful to understand how a fox hunts prey it cannot see. First, a fox hears something that sparks her interest. She tilts her head so that each ear is at a different height above the ground, a technique that is typical of dogs, wolves, coyotes, and foxes – all members of the Canid family. By orienting her ears in this way, she is better able to determine the general location of her prey. Then, she approaches the prey she can hear, but not see, until the sound she hears aligns with the angle of the magnetic field of the Earth-when this happens, she knows precisely where her prey is located.

A coyote performing a precision dive in an attempt to catch a vole.

Amazingly, foxes who approach their prey from a Northeasterly direction are successful 73% of the time, regardless of whether the fox is hunting in a field, in brush, or in deep snow. Her ability to sense the geomagnetic field is like a rangefinder-she is using the Earth’s magnetic field to determine her exact distance from her prey and she does not need to be able to see to gather this data. Regardless of the terrain and conditions, she listens, cocks her head to gather more information, uses her magnetic sense to determine her distance from her prey, and relies on her remarkable athleticism to attack her prey from above.

Sources

Cervený, J., Begall, S., Koubek, P., Nováková, P., & Burda, H. (2011, March 02). Directional preference may enhance hunting accuracy in foraging foxes. Retrieved January 12, 2021, from Royal Society Publishing.

Yong, E. (2011, January 11). Foxes use the Earth’s magnetic field as a targeting system. Retrieved January 13, 2021, from National Geographic