A red fox stands motionless on a snowfield, head cocked, ears pointed at the ground. Then it springs high into the air and dives headfirst into the snow, coming up, with luck, with a vole in its jaws. This hunting leap, known as "mousing", was filmed for Discovery's North America series, and it is one of the most remarkable pieces of winter animal behaviour you can watch.
How a red fox hunts mice under the snow
In winter, voles and mice live in tunnels beneath the snowpack, out of sight. The fox finds them by sound. Red foxes can hear a mouse squeak from about 100 m away and can pinpoint a sound to within a single degree in the 700–3,000 Hz range.
The hunt follows a set pattern:
- Listen. The fox stops, tilts its head and turns its ears to triangulate the noise.
- Creep. It edges forward a step at a time until it is in position.
- Leap. It jumps high, steering with its bushy tail in mid-air, and drops onto the target, which can be up to 5 m away.
Do foxes use Earth's magnetic field to aim?
The most intriguing research on mousing comes from the Czech Republic. Over two years, Jaroslav Červený and a 23-strong team of wildlife biologists and experienced hunters, working with Hynek Burda and colleagues, recorded almost 600 mousing jumps by 84 wild foxes. Their results, published in Biology Letters, were striking:
- Foxes strongly preferred to jump towards the north-east, about 20 degrees off magnetic north.
- North-east jumps succeeded 73% of the time, and jumps in the opposite direction 60%.
- Jumps in all other directions succeeded only 18% of the time.
- The preference held regardless of time of day, season, cloud cover or wind direction, and mattered most when the prey was hidden by snow or tall grass.
Červený's explanation is a "rangefinder". In the northern hemisphere Earth's magnetic field slopes downward at 60–70 degrees. If a fox can sense that slope, it could creep forward until the sound of its prey reaches it at the same angle. At that point the mouse is always the same distance ahead, and the fox knows exactly how far to jump. Nobody yet knows how a fox would sense the magnetic field, and the idea remains a hypothesis, but it would explain why aim improves so dramatically in one direction.
Red fox facts
- Size: adults weigh 2.2–14 kg, with a body length of 45–90 cm plus a tail of 30–55 cm. Vixens are 15–20% lighter than males.
- Range: the red fox is the most widespread member of the order Carnivora, found across the Northern Hemisphere and introduced to Australia.
- Diet: mainly small rodents, along with rabbits, birds, insects, fruit and seeds when prey is scarce.
- Winter coat: dense, soft and long, especially in northern populations.
Watching foxes in winter
Fresh snow makes their hunting easy to spot: look for lines of neat, single-file tracks and small craters where a fox has dived. Keep your distance, use binoculars or a long lens, and never feed a wild fox. Watching a fox mouse undisturbed is the real reward.
Related reading
- A Red Fox’s Headfirst Pounce into Snow
- Eleven Fox Photographs: Fur, Snow and Small Changes of Pose
- A Roadside Fox Found Alive: What the Original Rescue Account Establishes
- Fox Grom’s reflective husky photographs
- a dog enjoying snow in Leukerbad
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