Foxes jump in a north-easterly direction

February 4, 2013 6:27 AM

Foxes hunt rodents in the snow by listening for their movements and leaping high to pounce on their prey. Interestingly, they hunt most successfully when they jump in a north-easterly direction - 73% of the time. Jumping in the opposite direction has a 60% success rate. Pouncing in other directions was successful only 18% of the time. This was consistent regardless of time of day, season of year and weather conditions.

The current theory is that the foxes have a magnetic sense that helps them pinpoint their prey. If you're thinking that this sounds rather bizarre, you're not alone: one of the first people to study the magnetic sense of birds, Roswitha Wiltschko, commented, "This explanation… has plausibility only because there’s hardly any other mechanism that indicates directions.”

There's several mechanisms by which creatures can detect magnetic fields. These include small crystals of magnetite which can attract or repel each other indirectly generating a nervous signal, and a molecule called cryptochrome which is found in the retina. This molecule is found in common birds like robins; astonishingly you can disable a robin's magnetic sense by blindfolding it's right eye.

posted by Stark (65 comments total)

EVERYTHING ABOUT THIS POST RULES
posted by Greg Nog at 6:33 AM on February 4 [21 favorites]

What about foxes raised in Australia?
posted by The 10th Regiment of Foot at 6:34 AM on February 4 [2 favorites]

A cryptochrome? Oh god, what an amazing word.
posted by Sokka shot first at 6:35 AM on February 4 [4 favorites]

clearly, rodents are moving to the northeast.
posted by quonsar II: smock fishpants and the temple of foon at 6:43 AM on February 4 [2 favorites]

you can disable a robin's magnetic sense by blindfolding it's right eye.

Well, that sounds easy enough.
posted by goethean at 6:51 AM on February 4 [30 favorites]

I would think that an obvious alternative theory is that rodents have a magnetic sense which helps them avoid foxes.
posted by XMLicious at 6:52 AM on February 4 [2 favorites]

Eventually all the foxes will be in Maine... And all the robins will look like Pirates.
posted by HuronBob at 6:52 AM on February 4 [13 favorites]

Červený’s next move should be to disrupt the magnetic field around the fox to see if that interferes with their ability to catch mice. “But doing such a study will obviously be very challenging, given that it would involve altering the magnetic field over a large, outdoor area!”

Maybe you could put a magnetic collar on the fox?
posted by 1970s Antihero at 6:55 AM on February 4

Magnetic Mr. Fox
posted by Kabanos at 6:56 AM on February 4 [9 favorites]

I'm just going to leave this here.
posted by nevercalm at 6:57 AM on February 4 [17 favorites]

>pounce ne
You pounce and devour a tasty rabbit!

>pounce se
Nothing happens.
posted by RobotVoodooPower at 6:59 AM on February 4 [63 favorites]

Fucking foxes, how do they work?
posted by octothorpe at 7:11 AM on February 4 [6 favorites]

"Fucking foxes, how do they work?"

Since magnets don't actually "fuck", the phrase "fucking magnets, how do they work?" means one thing... your question asks something else entirely. But, to answer it, the fox Kama Sutra pretty much has only one page.
posted by HuronBob at 7:13 AM on February 4 [5 favorites]

Awesome science! Great use of university time.
posted by BlueScreen at 7:21 AM on February 4

Science has confirmed what we already knew: Fox leans to the right.
posted by Strange Interlude at 7:27 AM on February 4 [36 favorites]

"But doing such a study will obviously be very challenging, given that it would involve altering the magnetic field over a large, outdoor area!”

Remember Tarkovsky's Stalker? Yeah, turns out this was the actual incident that started it all.

WARNING WARNING DO NOT ATTEMPT TO DE-MAGNETIZE THE FOXES WARNING
posted by Doleful Creature at 7:31 AM on February 4 [2 favorites]

This sounds daft - they equate the magnetic field as being akin to a flashlight pointing at the ground and when the flashlight reaches the sound source they pounce, but how on earth does that account for the 60% success rate when pointing the opposite direction? The magnetic field/flashlight would just be pointing up in the air right?
posted by zeoslap at 7:34 AM on February 4 [2 favorites]

Awesome science! Great use of university time.

If their results hold up, it is indeed awesome - amazingly counterintuitive, and may lead to further cool findings about a subject one would expect to be finished by now.
posted by Dr Dracator at 7:35 AM on February 4 [1 favorite]

I like how they challenge you to come up with another explanation (almost like we're talking about science or something) but don't give you much more than a thumbnail of their data and then ponce on about their conclusion. For all I know every observation was made from the very same blind.

An easy test of this hypothesis - foxes should prefer the same directions in the US Midwest but have a 30° - 40° skew in northern Canada and Alaska.
posted by Kid Charlemagne at 7:46 AM on February 4 [7 favorites]

This sounds like a dubious theory.
posted by steef at 7:46 AM on February 4 [2 favorites]

But, to answer it, the fox Kama Sutra pretty much has only one page.

That's because a majority of the info is in the audiobook version - the illustrated page doesn't convey a lot of the nuance necessary to truly master that foxy 'scream like a pair of PCP babies choking the shit out of each other' technique.
posted by FatherDagon at 7:55 AM on February 4 [6 favorites]

Mention of this phenomenon is correlated with a statistically insignificant rise in interest in feng shui.
posted by fantabulous timewaster at 7:58 AM on February 4

WHAT ABOUT WHEN THE FOX JUST YELLS
posted by fleetmouse at 8:11 AM on February 4

I don't know about the magnetism part, but I've seen film of coyotes in the snow hunting exactly the same way (leap and pounce).
posted by Chocolate Pickle at 8:11 AM on February 4 [1 favorite]

So who knew vulpine feng shui was a real thing?
posted by TedW at 8:21 AM on February 4

How fucking foxes work:

I had an internship watching video footage of an endangered species of fox on the Channel Islands, off the coast of California. They were a mix of captive-born and wild-caught foxes, and they were incredibly shitty at mating. My internship was literally scrolling through hours and hours of footage until I found mating attempts, and then I'd slow down and take very careful notes to see what was going wrong. Often, the male would mount the female, but not actually get his penis in, so he'd just thrust around on top of her back for a while. Often, the female would freak out when the male tried to mate, and run away. On those rare occasions when the foxes got it together enough to successfully intromit, sometimes it would work and they'd be blissful foxes until the male ejaculated and they went on their merry ways.

But it turns out that fox genitalia is weird. Fox penises and vaginas engorge with blood and they get stuck together in what is called a "copulatory knot," sort of like a lock and key, making sure that all the sperm gets in there and STAYS IN THERE, dammit. And sometimes what happens is that the foxes are ready to disengage before their copulatory knots are ready to let them disengage. And so, sometimes, they get stuck, endquarter to endquarter. The male can't get out, the female's trying to get away, and they run in circles pulling in opposite directions until something gives and they pop apart and can go off and try to regain their dignity and pain-free genitalia.
posted by ChuraChura at 8:24 AM on February 4 [132 favorites]

A fox in a Faraday cage flounders fastest.
posted by blue_beetle at 8:47 AM on February 4 [1 favorite]

Are there any prey that have adapted to this by evolving a "stand to the south-west of foxes" instinct?
posted by deathpanels at 8:49 AM on February 4 [5 favorites]

Is it possible that most foxes are just "sided" in the way that humans have a dominant hand? The Discover blog seems to suggest in a few places that the kind of data they have might rule that out, but it isn't entirely clear.

Great post!
posted by OmieWise at 8:50 AM on February 4 [1 favorite]

But OmieWise, they're stronger to the compass north-east, which isn't related to which side of the fox is facing where. If foxes were dominantly left-handed, that effect would be same even if they were facing south-west.
posted by forgetful snow at 9:18 AM on February 4

Cows and deer tend to align themselves in a north-south direction.
posted by dephlogisticated at 9:28 AM on February 4 [2 favorites]

Oh, of course. I was somehow thinking of this as a static situation.
posted by OmieWise at 9:28 AM on February 4

Fox went out on a chilly night
His cryptochrome would set him right
Many a leap to make that night
And always to the north east
North east, no-orth east

Many a leap to make that night
And always to the north east.
posted by yoink at 9:29 AM on February 4 [9 favorites]

I can almost hear the Watkins siblings singing, yoink.
posted by weston at 9:41 AM on February 4 [1 favorite]

nevercalm: "I'm just going to leave this here. "

Oh, how I love them canines. That video always cracks me up.
posted by InsertNiftyNameHere at 9:51 AM on February 4

Are there any prey that have adapted to this by evolving a "stand to the south-west of foxes" instinct?

Rabbits usually run in a circle. I wonder if this is to constantly cause the predator to reajust its magnetic alignment?
posted by The 10th Regiment of Foot at 9:52 AM on February 4

I would imagine it's because a rabbit can more readily alter its direction than the larger, heavier predators chasing it, whereas it has no comparative advantage when running in a straight line.
posted by dephlogisticated at 10:04 AM on February 4

Well, there's magnets, and then there's the sun rising in the east and setting in the west thing. Not sure how that would help in hunting (like the magnetic sense theory could explain,) but it would at least allow animals to know where N/E/S/W is.

And speaking of the earth's magnetic field, I found this incredibly interesting. (As is pretty much everything on that blog.)
posted by jetsetsc at 10:04 AM on February 4 [3 favorites]

I would imagine it's because a rabbit can more readily alter its direction than the larger, heavier predators chasing it, whereas it has no comparative advantage when running in a straight line.

True, but any predator with the intelligence level of a beagle (read: not so bright) knows to turn with the rabbit and cut off the circle.
posted by The 10th Regiment of Foot at 10:11 AM on February 4

Jetsetsc, I was just reading about how some paint pigments contain magnetic elements, which also align themselves to compass directions as the paint is drying, and can be very useful in dating cave paintings. I was wondering exactly what the basic research of charting out when each reversal happened. I suppose it's things like ancient pacific island cooking rocks.

Dude. Fucking science.
posted by fontophilic at 10:19 AM on February 4 [2 favorites]

YES SCIENCE
posted by Specklet at 10:22 AM on February 4

It's interesting that this ended up being related to magnetism. My first hypothesis would probably be related to NE being a low risk direction for casting a shadow that might give away an approach.
posted by feloniousmonk at 10:26 AM on February 4 [5 favorites]

NE being a low risk direction for casting a shadow that might give away an approach.

Or prevailing winds in the Northern Hemisphere.
posted by The 10th Regiment of Foot at 10:32 AM on February 4 [7 favorites]

I came to post the foxes-on-trampoline video but was not surprised I was beaten to it. Foxes are adorable to watch. (Although probably not if you have ChuraChura's job.)
posted by immlass at 10:34 AM on February 4

True, but any predator with the intelligence level of a beagle (read: not so bright) knows to turn with the rabbit and cut off the circle.

Rabbits and other small prey animals typically zig-zag, rather than circle. It's an inertial thing; it requires more energy for a large animal to change direction compared to a small animal, so the small animal gains a small advantage every time it alters direction. This video shows it pretty well.
posted by dephlogisticated at 10:45 AM on February 4 [3 favorites]

Usually, but rabbits circle. That's how a good rabbit dog brings them back to its master. They stay on the rabbit until they've turned it to intersect with their master's path. I don't know of other animals that will take such a predictable path.
posted by The 10th Regiment of Foot at 10:54 AM on February 4

All things serve the Beam.
posted by Addlepated at 11:08 AM on February 4 [3 favorites]

Interesting idea, and a magnetic explanation doesn't seem entirely impossible but, the mechanism offered in the Discover post sounds mighty fishy:

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.

In other words, they're proposing this as a way to measure whether or not a sound is coming at the fox 30 degrees from vertical? If there's one thing we know all mammals are instrumented for, it's sensing local gravity. Proposing an entirely new mechanism that only works under very limited conditions and does the same thing seems daft, without a lot more evidence. I assumed they were arguing that the presence of the mouse modifies the local magnetic field at a level the fox can sense, which seems mighty unlikely, but at least makes use of the magnetic field. (Of course this could be a case of mangled journalism.)

Given the large-scale patterns in the direction of wind, sunlight, and often terrain, eliminating other more likely explanations in the field seems a difficult task. Measuring the same fox behaviour in various momentary conditions isn't enough to eliminate the possibility that either the environment or the actors have adapted to longer term patterns. To pick an extreme example, I've seen several arctic environments where you an instantly tell which direction the prevailing winds blow by looking at the direction of the sastrugi on the surface of the snow. A fox in those places would almost certainly adapt their hunting strategy in response to those features. It isn't hard to imagine a less obvious version, where the time-of-day during direct sunlight or the prevailing winds change the snow consistency near objects in a way that makes things easier for the fox. That foxes have adapted a strategy that usually puts them in the leewind or shadow-free side of prey when and where they usually hunt also seems more likely than magnets.

Without a controlled experiment or detailed mechanisms, I'm skeptical.
posted by eotvos at 11:19 AM on February 4 [4 favorites]

What about foxes raised in Australia?

Please stop trying to flush them down the toilet. That is not science.
posted by qxntpqbbbqxl at 12:06 PM on February 4 [15 favorites]

ChuraChura: "Fox penises and vaginas engorge with blood and they get stuck together in what is called a "copulatory knot,""

This must have been what happened with the pair of dogs we saw as kids. They were stumbling up and down the street, joined, for a long time, and made for much amusement among us and embarrassed parents who had a difficult time explaining what was going on.
posted by exogenous at 12:27 PM on February 4

My dog catches mice like this and she always sets herself up so she's pouncing to her right. Popcorn and tennis ball based experiments have shown that she can, in fact, only catch things located on that side of her body. Throwing things to her left results in amusingly bad misses or a dog doing a 180 at speed.
posted by fshgrl at 1:00 PM on February 4

Fshgrl: does your dog have impaired vision in her left eye?
posted by aeschenkarnos at 1:24 PM on February 4

Was it L S B Leaky who used to claim that 90% of the time the rabbit you were chasing would dodge to the right?
posted by jamjam at 1:53 PM on February 4

ox penises and vaginas engorge with blood and they get stuck together in what is called a "copulatory knot,"

Wolves have this too, I understand. Stops other wolves from getting in on some Round 2 action and subverting dominant wolf-sperm.
posted by smoke at 4:50 PM on February 4

No she can see fine. She's just right footed.
posted by fshgrl at 4:55 PM on February 4

From the actual authors of the study:

Mousing behaviour was observed by 23 experienced wildlife biologists and hunters in 84 wild red foxes (V. vulpes) in 65 localities in the Czech Republic, in different habitats, between April 2008 and September 2010, and at different times of day. The body orientation of a fox while preparing for a jump was recorded in 95 hunting series, in which a total of 592 hunting jumps were observed. Body orientation was measured with a compass with accuracy of 10° with the angle indicating the head direction. In 200 jumps, the immediate success or failure of the attack could be clearly determined. We calculated means over repeated measures of individuals that were used in further analysis (second-order statistics). We analysed the heading direction of jumps with respect to the height of vegetation or snow cover, time of the day, season of the year, observer, sex and age of the fox, and other relevant variables.

TL;DR they observed many different foxes jumping at different times of day, in different locations, during different seasons. This would seem to rule out light angles or wind patterns as likely reasons for the direction of the jumps. I suppose the next obvious step would be to try to confuse some foxes with a magnetic field generator.
posted by BlueJae at 8:05 PM on February 4 [3 favorites]

Wolves have this too, I understand. Stops other wolves from getting in on some Round 2 action and subverting dominant wolf-sperm.

This is actually common to all canids (as far as I know) including domestic dogs.

http://en.wikipedia.org/wiki/Bulbus_glandis

http://en.wikipedia.org/wiki/Canine_reproduction

(Those are not links I would suggest clicking at work.)
posted by Vulpyne at 9:47 PM on February 4 [1 favorite]

That's an uncomfortable sounding eponysterical, "Vulpyne."
posted by ChuraChura at 4:39 AM on February 5 [3 favorites]

Does this mean we now know which way the quick brown fox was headed when he jumped over the lazy dog?
posted by TedW at 4:57 AM on February 5 [2 favorites]

"This explanation… has plausibility only because there’s hardly any other mechanism that indicates directions.”

Is that researcher from Seattle? In the rest of the world, we have this usually obvious glowing yellow orb that, on average, is South of us. She must have missed the memo about the dung beetles that navigate by the light of the Milky Way?
posted by Hello Dad, I'm in Jail at 5:26 AM on February 5

The Discover blog entry says

He found that the animals leapt in the same direction regardless of the time of day, season of year, cloud cover, or wind direction.

so it would appear to be unrelated to the position of the sun in the sky. But maybe they can sense neutrinos and somehow adjust for the Earth's rotation.
posted by XMLicious at 8:32 AM on February 5

Fox went out on a chilly night
His cryptochrome would set him right
Many a leap to make that night
And always to the north east
North east, no-orth east

Many a leap to make that night
And always to the north east.

He hoped for a healthy night hunt's yield
Observing Earth's magnetic field
He stalked, he ran, he leaped, he wheeled,
And always to the north east
North east, no-orth east

Many a mouse to catch that night
Leaping to the north east.
posted by Pirate-Bartender-Zombie-Monkey at 10:02 AM on February 5 [6 favorites]

I'm imagining Nickel Creek getting back together and recording an informative, kickass version about science and foxes.

For kids.
posted by Pirate-Bartender-Zombie-Monkey at 1:22 PM on February 5

A dog lover, whose dog was a female and in heat, agreed to look after her neighbours' male dog while the neighbours were on vacation.

She had a large house and believed that she could keep the two dogs apart. However, as she was drifting off to sleep she heard awful howling and moaning sounds. She rushed downstairs and found the dogs locked together in obvious pain and unable to disengage, as so frequently happens when dogs mate. Unable to separate them, and perplexed as to what to do next, although it was late, she called the vet, who answered in a very grumpy voice. After she explained the problem to him, the vet said, "Hang up the phone and place it down alongside the dogs." "I will then call you back and the noise of the ringing will make the male lose his erection and he will be able to withdraw." "Do you think that will work?" she asked. "It just worked for me," he replied.

via
posted by exogenous at 1:30 PM on February 12 [4 favorites]

A fox in a Faraday cage flounders fastest.
Nice alliteration, but a Faraday cage only screens electric fields, not magnetic.
posted by crazy_yeti at 11:10 AM on February 16