16 January 2015

A fox dives into DEEP snow - update #2



I first posted this video several years ago, but I find it to be endlessly fascinating.  A hat tip to 22 words for reminding me.

Addendum:  And a hat tip to several readers for pointing out that this diving skill has some intriguing scientific roots, nicely summarized at one of my favorite science blogs, Not Exactly Rocket Science:
Jaroslav Červený has found that when red foxes pounce, they mostly jump in a north-easterly direction. He thinks that they’re using the Earth’s magnetic field to hunt.

Červený spent over two years studying wild red foxes in the Czech Republic, with the help of a 23-strong team of wildlife biologists and experienced hunters. The team recorded almost 600 mousing jumps, performed by 84 foxes at a wide variety of locations and times.

They found that foxes strongly prefer to jump in a north-easterly direction, around 20 degrees off from magnetic north. This fixed heading was important for their success as hunters. They were more likely to make a kill if they jumped along their preferred axis, particularly if their prey was hidden by high cover or snow. If they pounced to the north-east, they killed on 73% of their attacks; if they jumped in the opposite direction, they success rate stayed at 60%. In all other directions, only 18% of their pounces were successful...

Červený suggests that a red fox could use the Earth’s magnetic field as a “rangefinder”, to estimate the distance to its prey and make a more accurate pounce. This targeting system works because the Earth’s magnetic field tilts downward in the northern hemisphere, at an angle of 60-70 degrees below the horizontal. As the fox creeps forward, it listens for the sound of a mouse. It’s searching for that sweet spot where the angle of the sound hitting its ears matches the slope of the Earth’s magnetic field. At that spot, the fox knows that it’s a fixed distance away from its prey, and it knows exactly how far to jump to land upon it...
This totally fascinating ability is discussed in more detail at the link, and illustrated here -


- from an article in Nature.  Evolution is so amazing.

Reposted from 2011 to add this video of a domestic dog pouncing the shadow of a bouncing baby:

13 comments:

  1. Max MeyersFebruary 25, 2011 at 7:43 PM

    This is beautiful!

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  2. lerchbaseFebruary 25, 2011 at 8:12 PM

    Far out. And none the worse because I originally read "moose" instead of mouse...

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  3. pambambooFebruary 25, 2011 at 11:47 PM

    But why the sad music?

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  4. James MacAonghusFebruary 26, 2011 at 5:50 AM

    Animals, eh, is there anything they can't do. I feel a bit sorry for the mouse - I hope he didn't have any plans for the rest of the day.

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  5. AvrilFebruary 26, 2011 at 8:32 AM

    This might interest you

    http://www.bbc.co.uk/news/uk-england-london-12573364

    ReplyDelete
  6. MaraKFebruary 26, 2011 at 12:52 PM

    Firefox is retrieving your file...

    ReplyDelete
  7. AnonymousFebruary 26, 2011 at 1:04 PM

    Some Czech researchers recently published their finding that foxes appear to be able to judge the distance and depth of their pounces by calibrating against an innate perception of the earth’s magnetic field. Nutshell explanation and helpful diagram here:

    http://blogs.nature.com/news/thegreatbeyond/2011/01/fox_rangefinder_sense_expands.html

    Further info and details of the mechanisms for biological magneto-reception here:

    http://blogs.discovermagazine.com/notrocketscience/2011/01/11/foxes-use-the-earth’s-magnetic-field-as-a-targeting-system/

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  8. AnonymousFebruary 26, 2011 at 2:39 PM

    I heard the other day that the foxes not only use their incredibly acute hearing to do this, but they can also sense magnetic fields, much the same as birds. Apparently the organ they do it with is located in (or behind?) the right eye, again the same as birds. They can actually "see" the mouse's magnetic field against the normal field of the earth.

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  9. MinnesotastanFebruary 26, 2011 at 3:42 PM

    Thank you, anons. That info re magnetic fields warrants a separate post. After the weekend...

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  10. charlieMarch 4, 2011 at 12:10 AM

    The explanation seems preposterous. I'll have to read the Nature article. But consider this
    1) would it not be more logical to assume that either the angle of sunlight matters more? in winter, northeast would be facing away from the sun in mid afternoon when it would be the warmest

    2) would it not be more logical to assume that the direction of the wind would matter immensly to accurate hearing or to keep ones scent downwind

    3) isn't it insane to to suggest foxes could not only sense magnetic fields but to be able to sense slopes in these fields??? bonkers.

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  11. MinnesotastanMarch 4, 2011 at 7:49 AM

    Charlie, it does seem preposterous, but as you read, pay attention also to the documented examples of cows and deer aligning themselves with magnetic fields.

    Migrating birds and turtles may use the earth's magnetic fields for their navigation, and I've previously blogged -

    http://tywkiwdbi.blogspot.com/2010/01/monarchs-use-earths-magnetic-field-to.html

    - about butterflies having magnetoreceptors.

    It's possible. It may or may not be proven, but it is possible.

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  12. AnonymousJanuary 16, 2015 at 11:04 AM

    or maybe the fox is sensing the perturbation to the magnetic field that is being caused by the movement of the prey? like tuning in a radio beacon, or seeing stacked lights?

    I-)

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  13. AnonymousJanuary 16, 2015 at 11:08 AM

    in that baby / dog video, i don't think there is any interspecies teaching going on. it looks like the dog is pouncing on the shadow that the baby is making on the floor. the dog is seeing a moving shadow as well as a reflection of light from the other room and jumping at the coincidence of the two?

    I-)

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