As one of those filial duties I pay for my mother’s subscription to BBC Wildlife magazine, and once she’s read it my mother passes the copies to me. So it was that last evening I was reading the May 2011 issue and came across this amazing report of foxes using the earth’s magnetic field. I hope I might be forgiven for reproducing the short news item here as it doesn’t otherwise appear to be online.

Magnetic foxes

Scientists reveal the otherworldly talents of red foxes.

The hunting skills of the red fox Vulpes vulpes are out of this world — literally. According to new work, this hunter taps into the cosmos to pinpoint prey.

The fox feeds mostly on small mammals such as mice and voles, and has a clever way of going about it. It often performs what is called mousing — leaping high into the air in an arc and landing on unsuspecting prey from above. Remarkably, it can pull this off in 1m-high grass (or, in winter, snow of that depth). It’s assumed that, under these conditions, the fox relies solely on hearing to locate its quarry.

But when a team led by Hynek Burda, from the University of Duisburg-Essen, Germany, scrutinised the hunting habits of wild foxes at various locations in the Czech Republic, they noted a peculiar trend: hunters tended to catch dinner most often when they were facing north. This was especially true if their prey was snuggled under vegetation or snow – the foxes then had a 75 per cent hit rate with north-facing strikes. Attacks in all other directions were mostly futile.

What’s so special about looking north? The researchers believe that the foxes use the Earth’s magnetic field to home in on prey.

Some other mammals, and also birds, are known to sense magnetic north — and some are thought to actually see it, when looking northward, as a bright (or dark) patch in their field of vision — a little like a sunspot in a camera lens — due to special receptors in their eyes. If foxes have this ability, they could use its fixed position to gauge their distance to prey.

Think of it as a circle of light from a headlamp aimed, say, 1m in front of your feet. No matter where you go, the circle is always 1m ahead. Thus, a northward-facing fox that has located prey with its hearing needs only to creep forward until that location is within the circle of light. At that point, it knows it’s exactly 1m away. All that’s left to do is pounce.

It’s the first evidence of an animal using the Earth’s magnetic field as a hunting tool.

Animal Magnetism
» This is the first case of an animal using the Earth’s magnetic field to judge distance rather than direction.
» Except for jump direction, no other factor — from an animal’s age/sex to the season, wind direction or time of day — affected the observed pattern.
» Animals that sense magnetic north probably also sense magnetic south to a degree. Indeed, 60 per cent of fruitful attacks that were not northward faced due south. Overall, 90 per cent were along the north-south axis.
» Cattle and deer tend to line up along the north-south axis – except near high-voltage power lines that disrupt the field.
» When foxes could see their prey they had success in all directions.