How Does a Fox Hunt Under Snow?

Step 1 of 5

Two ears give a direction.

A sound from the left reaches the left ear less than a thousandth of a second earlier, and slightly louder. The brain turns that difference into a direction — and a fox's ears are big, far apart and steerable.

Step 2 of 5

Tilting the head gives a depth.

Left and right is not enough; the fox needs to know how deep. By tilting and turning its head it changes the difference between the ears and works out the angle down as well.

Step 3 of 5

Then it commits, blind.

The fox rears up and dives nearly vertically, punching through the crust with its nose. It cannot see the mouse at any point — the whole strike is aimed at a memory of a sound.

Step 4 of 5

Low sounds carry through snow.

Snow soaks up high notes quickly but lets low rustling and scratching through. A fox's hearing is unusually sharp at exactly those low frequencies.

Step 5 of 5

It works better facing one way.

Foxes pounce far more successfully when facing roughly north, and nobody is certain why. The leading idea is that they use the Earth's magnetic field as a fixed line to judge distance against.

A fox's pounce carries it a body length or two into the air. The tail swings to keep the nose pointed at the target on the way down.