Thursday, January 23, 2014

Animal magnetism--literally (and a note to some young fans)

The dam. 20 January 2014
The dam is in good shape. Maybe better than any of the four  I've seen in the last two years. Let's hope it holds.

You all may recall the neat videos of a fox hunting that I captured last month.
You can see the sequence of three videos here.  

If you look closely at the third video, you can just see the prey escape.

The fox failed to catch its prey. Talking with various friends, the question arose; how often are fox successful in pouncing. Good question, isn't it?  

The answer depends, amazingly, on which compass azimuth they are aligned with.  It seems that foxes have a magnetic sense.  If the fox is facing north to northeast, it's successful in 73 % of its pounces. Facing other directions, the success rate is 18%.

A quick search revealed other examples of animals having some sort of internal compass.

  • Water birds are most likely to land in a north-south line.
  • Dogs are most likely to excrete while on a north-south axis.
  • Migrating birds have a compass map of the world, and use it to know where they are.
  • Cattle and deer tend to browse on a north-south axis.
  • Loggerhead Sea Turtles have a magnetic sense and use it to navigate.
  • Sockeye Salmon have a magnetic sense, and use it to return to their spawning grounds.
  • Spiny lobsters appear to have a" magnetic map" that they use to know their location in the world.
That's what I found with just a quick search. There are probably other examples. It seems pretty clear that many animals have the ability to sense earth's magnetic field.

And this sense allows them to do more than recognize a north-south line. Every place on earth has a unique magnetic map; a map that some animals appear able to recognize.

So, after reading this, maybe you are curious to know what direction the fox was aligned when it failed to catch dinner?  Just a little bit south of west. 


Hey, Jack, I'm not making this up myself.  See below for some references.

And a special note to some young fans who left me a message via camera on 19 January 2014 at 2:18 pm. I do read my comments; and I did see yours. I also enjoyed your art installation. It was great. I look forward to your next one. I'm glad you're enjoying the blog; really glad.

More later.

"Pathfinders", by Doug Stewart., February/March issue of National Wildlife.

Monday, January 6, 2014

Snug as a bug in a rug

the dam and ice-covered pond. 4 Jan 2014.
I had a chance to check the camera and the dam last Saturday. There was snow on the ground, and I was
looking forward to seeing lots of track. I thought I might learn a thing or two about animal activity around the beaver pond.

I did learn a thing or two--just not what I expected.

What surprised me was that there was very little track of any sort in the area, and absolutely no beaver tracks.

I assume that means the beavers are doing what beavers do. That is, staying under the ice where they are safe from predators. They've already stashed a lot of food under the water, in the form of sticks. The entrance to their den is under water so, again, no predators can get at them when ice forms on top of the pond.

This drawing gives shows you how it works, and saves me a thousand words to boot. Can you imagine how our beaver family is happily and safely whiling away the winter under the protection of the ice. They've got a house, food, shelter--everything but high def TV.  And no predators can get at them.

While scouting around, I saw a Great Blue Heron. Probably, it's the same one the camera picked up in this video on the 30th of December.

This is not the only Heron that has benefited from a beaver pond. See this link for another story of the symbiosis of beaver ponds and birds.

More later.