Thursday, July 26, 2012

The Fox's Animal Magnetism

For a while now, it has been thought that birds could see the magnetic field, in order to help them migrate.  It has been hypothesized that, when they are facing north, they can see a little blurry patch at the bottom of their eye.  If they are facing east or west, then they can't see the patch, so they know where to put the patch in their field of vision to get where they want to go.  Recent research by a Czech team of scientists seems to indicate that the red fox can also use the magnetic field, but for a different purpose: hunting.

The red fox (Vulpes vulpes) ("Least Concern" by the IUCN) has the largest geographical distribution of any member of the Carnivora, with habitat on all of the continents except for South America and Antarctica.  In North America, it inhabits the United States and Canada, in Europe and Asia it lives almost everywhere, and in Africa it lives in Morocco, Algeria, Tunisia, Egypt, Sudan, and Libya.  Not only does it possesses the range shown in the map below, it has been introduced to Australia, where, like the Dingo, it poses a threat to native species.

The red fox hunts by leaping up into the air, and coming down right on top of its prey, literally (for the prey, at least) appearing out of nowhere.  But how to pinpoint its jump?  The answer lies in the magnetic field, which is visible to the foxes.  But how does this work?  Out of all of the explanations set forth by various journals and such, I thought the explanation from Nature was easiest to understand.  Here's what they have to say:

"Think of a laser pointer attached to you that always points slightly downwards in the same direction. Now think of some object on the ground. If you walk towards the object until the laser spot is on top of it you know that object is a set distance away."

Generally, it was thought that foxes would pinpoint their location solely using their very acute sense of hearing.  But then the Czech team found that, when the red fox was leaping in a northerly direction, 74% of the attacks were successful, while the leaping attacks in other directions had the success rate of a mere 18%.  That's a very big difference, and seems to point to the magnetic field theory.
A picture of the red fox outside of the house that our friends the Beckleys rented in Breckenridge one summer.  Awesome place to stay, especially if you are looking to escape the summer heat!  Photo Credit: Julie Neher

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