Why do migrating birds fly in a V formation?

September 21, 2014 3:02 PM

"It was always assumed that V-formation flight was learned from the adult birds. But these guys are all the same age and they learned to fly from a human in a microlight. They learned V-formation flying from each other. National Geographic reports on some of the fascinating intricacies of the V formation observed in migrating birds.
posted by paleyellowwithorange (28 comments total)

Yes, but do you know why one side of the V is longer?
posted by zamboni at 3:11 PM on September 21, 2014 [16 favorites]

And when they fly in that V formation, did you ever notice that one side of the V is longer than the other? Do you know why that is?

There are more birds on that side.
posted by Floydd at 3:12 PM on September 21, 2014 [12 favorites]

Iced by zamboni!
posted by Floydd at 3:13 PM on September 21, 2014 [5 favorites]

How can you fly in a V formation without being taught? This one weird old trick may surprise you.
posted by nzero at 3:37 PM on September 21, 2014 [4 favorites]

I'm somewhat surprised the article claims that the leader bird in a V isn't experienced/adult/been there-done that.

But that statement is mentioned casually...apparently based on some microflight stuff.

When N=1 I tend to wait for more data....
posted by CrowGoat at 3:46 PM on September 21, 2014

the upper-crust birds fly portside out, starboard home.
posted by bruce at 3:51 PM on September 21, 2014 [6 favorites]

the poshest place on vortex street
posted by hortense at 4:01 PM on September 21, 2014 [1 favorite]

I've been photographing feathers for a while now and have consistently been amazed at their structure. In the course of all this, I laid hands on a pair of duck wings (yes, gross. I'm vegetarian, too.) One thing that was really interesting was seeing how they felt when i moved them thru the air. They resist movement because they catch air so well. So yes, they generate lift when they push down, but when they pull up the wings are also exerting some resistance as well, sort of like a swim fin.

So I'd assume that the bird feels that resistance, and because it's flying all the time, can just figure out what feels better, easier. Sure, it would be nice to have an adult around to tell them what to do, but without it, they're still going to figure out a lot of stuff on their own.
posted by nevercalm at 4:07 PM on September 21, 2014 [5 favorites]

This is all very interesting, but National Geographic missed an obvious connection here.
posted by flapjax at midnite at 4:12 PM on September 21, 2014 [2 favorites]

Why is this hard to understand? Birds want to fly in a direction. Flying is hard. Flying behind a buddy heading in the direction you want is physically easier than going alone.

I mean, are we doing studies about how amazing it is that cats seem to just naturally sleep on fluffy beds without anyone telling them to do so?

Amazing! The cat just seems to gravitate toward the cozy spot! There must be a neurological explanation!
posted by Cool Papa Bell at 5:56 PM on September 21, 2014 [4 favorites]

cool papa bell, do cats sleep on fluffy beds in a specific orientation relative to earth's magnetic field, so they can get somewhere they need to be to survive? my guess would be no, but i might be persuaded to accept funding for any new cat research that doesn't hurt the cats.
posted by bruce at 6:28 PM on September 21, 2014

bruce: "cool papa bell, do cats sleep on fluffy beds in a specific orientation relative to earth's magnetic field..."

Well, not cats, necessarily.
posted by symbioid at 6:35 PM on September 21, 2014

cool papa bell, do cats sleep on fluffy beds in a specific orientation relative to earth's magnetic field

I think you're conflating the V formation with the urge to migrate itself. They're not the same thing.

But hey, if it makes you feel better to be fussy and try to correct me, then let me play along. "Holy shit, no way! GTFO! I never thought of it like that before!"

Nothing but love for you, sparky.
posted by Cool Papa Bell at 7:27 PM on September 21, 2014

you asked a cat science question in a bird thread (ok), i asked another one, and now you're meowing at me?
posted by bruce at 7:50 PM on September 21, 2014

Lanchester–Prandtl lifting line theory: This was a stock question that showed up in my final BSC Aero Engineering exam at Queens University Belfast back in 1976: Calculate the energy saved, for a given bird weighing w, positioned x and y etc. from the bird in front. I recall that it was one of the few questions I think I got right during the whole ordeal.
posted by marvin at 8:10 PM on September 21, 2014 [1 favorite]

I'm somewhat surprised the article claims that the leader bird in a V isn't experienced/adult/been there-done that.

But that statement is mentioned casually...apparently based on some microflight stuff.

When N=1 I tend to wait for more data....

More precisely, CrowGoat, the leader bird in a V isn't necessarily experienced/adult/been there-done that - because they take turns flying in that highest-energy position.

Since all the birds rotate through that position, it follows that the lead bird at any given point isn't in that spot because of age and experience.
posted by IAmBroom at 8:52 PM on September 21, 2014

It doesn't seem all that mysterious to me. When birds are migrating, they are working at their metabolic limits. You can actually see geese with their tongues hanging out as they struggle to keep up.

In lots of endurance sports -- cycling, canoeing, swimming, auto racing, even running -- you find yourself struggling to keep up with the pack and then suddenly you fall into the perfect position and it feels like someone attached a tow line. You start breathing easier and your muscles work easier. The instant you fall out of position, it feels like someone grabbed you from behind. It doesn't take long to figure out how to work easier. I would expect birds to easily figure it out as well. The feedback is strong and their life depends on it. They really are working at physiological limits. If you can't keep up, you are probably going to die.
posted by JackFlash at 9:08 PM on September 21, 2014 [2 favorites]

Because vortices are the best and they want everyone to know. So they make a big letter 'V'. (Actually, their really bad for drag, so why not use all the wasted energy from the guy in front to help yourself)

C-130 wingtip vortices
Passenger plane
Modern F1 aerodynamics are crazy
posted by TheJoven at 9:42 PM on September 21, 2014 [1 favorite]

U V, all right?! They learned it by watching U V!
posted by aaronetc at 9:56 PM on September 21, 2014 [2 favorites]

Why is this hard to understand?

It doesn't seem all that mysterious to me.

Some of us aren't scientifically-minded or sporty-types, so this kind of article is quite informative.

As I was walking home yesterday afternoon, I was admiring a flying V of birds; I wanted to know why they fly in that formation, so I looked for an informative article from a reliable source, and subsequently shared it for the benefit of other MeFites like me.
posted by paleyellowwithorange at 10:08 PM on September 21, 2014 [4 favorites]

Back off man, I'm a cat scientist.
posted by XMLicious at 10:25 PM on September 21, 2014

Sorry, paleyellowwithorange, I wasn't implying that it wasn't an interesting article. It certainly is. What I was objecting to is the part of article that expresses mystery in how these dumb animals could possibly figure this out without being taught (or a bunch of physicists to explain it to them).

The simple answer is that the feedback is strong, they can instantly feel the changes, so they can figure it out on their own and they are highly motivated because their very lives depend on figuring it out. A bird that falls behind the flock stands little chance of making it to their migratory destination on just their own energy.

If a bird is in the right position but lets their flapping get out of sync or slides slightly out of optimal position it will begin to fall behind. And then they have to work desperately hard to catch up working on their own. They will quickly learn not to slip up again.
posted by JackFlash at 10:59 PM on September 21, 2014 [1 favorite]

JackFlash has the real answer. Next up: How do wolf cubs learn to eat meat, without a momma around to tell them that they are carnivores? And how can stray cats learn that belly rubs are pleasant, getting chased by dogs is scary, and fleas itch?

Because, duh, feedback informs the individual.
posted by IAmBroom at 5:05 AM on September 22, 2014

Scientists have found that if they prevent certain sequences in birds' genomes from being expressed, they fly in formations shaped like other letters of the alphabet and punctuation marks.
posted by XMLicious at 5:33 AM on September 22, 2014 [3 favorites]

Here's the start of the article:

Why do some birds fly in a V?

Most people would say that they do it to save energy, which would be right. But it turns out that birds in a V are actually pulling of a feat that’s more complicated and more impressive than anyone had imagined.

Here is the standard explanation for the V-formation:

As a bird flaps, a rotating vortex of air rolls off each of its wingtips. These vortices mean that the air immediately behind the bird gets constantly pushed downwards (downwash), and the air behind it and off to the sides gets pushed upwards (upwash). (See this image if that’s not clear.) If another bird flies in either of these upwash zones, it gets free lift. It can save energy by mooching off the air flow created by its flock-mate.

This all makes sense, but it represents decades of largely theoretical work. Scientists calculated how air should flow around a flying bird based on what we know about planes, but almost no one had taken any actual measurements.

You'd almost think the guy who wrote the article knew they do it to save energy, and was writing about some interesting details that had been learned! Fortunately, the stern gang of MeFites knows better, and has taken it upon themselves to point out what an ignoramus he is and how pointless the entire article is. They knew it all along!
posted by languagehat at 7:55 AM on September 22, 2014 [2 favorites]

One interesting thing is that some scientists believe that the bird actually leading the flock is not always the one at the front of the V but one that is farther back in the V. To understand how this works, you need to know that there are two different components to the air drag felt by the bird. There is the strong air resistance up front, from pushing through the air, but there is also a smaller parasitic drag from behind due to the vortices coming off the wings. It is like the bird is being pulled backwards by their vortices.

These parasitic vortices are why newer airplanes have those vertical fins on the end of the wings. The fins reduce the vortices and increase efficiency. You can also reduce the parasitic vortices by drafting.

When two cyclists, for example, are drafting, the cyclist in the back feels less air pressure up front and feels like he is being pulled. But there is also an advantage for the cyclist in front. Because the cyclist behind is in his vortex, the lead cyclist feels less parasitic drag from behind. It feels like a slight push. The effect is smaller than the rider in back feels, but it is still there.

So for birds, lets assume that it is actually the fourth bird back in the V who is the most experienced and determines the correct heading necessary. If that bird turns slightly to the right, all the birds behind will also turn to the right to stay in the best drafting position.

But what about the birds ahead of the fourth bird? They will feel a slight increase in the drag from behind because the fourth bird is no longer in their vortex so they will move to the right as well to maintain the optimum position in front of the bird behind them to reduce the drag. This propagates forward to the bird at the front of the V and soon all birds are on the new heading steered by the true leader, a bird towards the rear.

The real mystery is how they decide who is leading and who is following.
posted by JackFlash at 8:26 AM on September 22, 2014

Guilty as charged, languagehat.
posted by IAmBroom at 8:34 AM on September 22, 2014

So do geese get into punch-ups when one of them doesn't take a pull in front?
posted by TheWhiteSkull at 8:44 AM on September 22, 2014