Why Birds Fly In a V Formation

sciencehabit writes "Anyone watching the autumn sky knows that migrating birds fly in a V formation, but scientists have long debated why. A new study of ibises — where researchers took to microlight planes and recorded birds strapped with GPS in-flight — finds that these big-winged birds carefully position their wingtips and sync their flapping, presumably to catch the preceding bird's updraft and save energy during flight."

Comments

This is new?

[Anonymous Coward]

I remember being taught this as a child in the 80s.

Re:This is new?

[noobermin]

If you read the article, this has been posited, but now it has been tested by the experiment mentioned in the summary.

Re:This is new?

[iggymanz]

which was done decades ago, I laughed at the 80s mention, I was taught as child in the 60s and in 70s this was popular science fair homemade wind tunnel experiment.

About once a month slashdot runs article on "discovery" or "invention" that is decades old

Re: This is new?

[noobermin]

I'm assuming that they're saying because it works with plane wings, they can expect that's why birds do it (TFA says this), but I'm assuming they never tested the hypothesis on birds.

In fact, TFA suggests that a more rigorous test would be to put birds in a wind tunnel, which obviously wouldn't be too fun for the birds.

Re:This is new?

[nedlohs]

Right, because the guy should have remembered being taught it before he was born rather than so late in the game as when he was a child.

Re: This is new?

[Dan East]

They should also test an unladen swallow.

Re: This is new?

[i.r.id10t]

European or African?

Re:This is new?

[Rutulian]

This was my first reaction too. However, reading the article (I know, I must be new here) clears it up,

There are two reasons birds might fly in a V formation: It may make flight easier, or they’re simply following the leader. Squadrons of planes can save fuel by flying in a V formation, and many scientists suspect that migrating birds do the same. Models that treated flapping birds like fixed-wing airplanes estimate that they save energy by drafting off each other, but currents created by airplanes are far more stable than the oscillating eddies coming off of a bird. “Air gets pretty darn wiggy behind a flapping wing,” says James Usherwood, a locomotor biomechanist at the Royal Veterinary College at the University of London in Hatfield, where the research took place.

Just as aerodynamic estimates would predict, the birds positioned themselves to fly just behind and to the side of the bird in front, timing their wing beats to catch the uplifting eddies. When a bird flew directly behind another, the timing of the flapping reversed so that it could minimize the effects of the downdraft coming off the back of the bird’s body.

“From a behavioral perspective it’s really a breakthrough,” says David Lentink, a mechanical engineer at Stanford University in Palo Alto, California, who was not involved in the work. “Showing that birds care about syncing their wing beats is definitely an important insight that we didn’t have before.”

And from the actual research article,

Many species travel in highly organized groups. The most quoted function of these configurations is to reduce energy expenditure and enhance locomotor performance of individuals in the assemblage. The distinctive V formation of bird flocks has long intrigued researchers and continues to attract both scientific and popular attention. The well-held belief is that such aggregations give an energetic benefit for those birds that are flying behind and to one side of another bird through using the regions of upwash generated by the wings of the preceding bird, although a definitive account of the aerodynamic implications of these formations has remained elusive.

We conclude that the intricate mechanisms involved in V formation flight indicate awareness of the spatial wake structures of nearby flock-mates, and remarkable ability either to sense or predict it. We suggest that birds in V formation have phasing strategies to cope with the dynamic wakes produced by flapping wings.

So, it's a little bit of a behavioral science study...is saving energy why they do it, or is saving energy just a happy consequence? And it's also a bit of a mechanism study...to gain the most aerodynamic benefit requires adjustment of the wing and position to meet the updrafts, so how well do the birds do this?

Re:This is new?

[VortexCortex]

Right, because the guy should have remembered being taught it before he was born rather than so late in the game as when he was a child.

Well, whatever we do, by no means should science draw from the past experience and knowledge of the world.

If we ever create a world-wide instantaneous knowledge discovery system, it will be the end of all progress.

In other words: That he does not know it upon birth is a damn design flaw, human.

Re:This is new?

[bwanagary]

Seriously dudes, its much simpler than that.
Birds fly in a 'V' formation because they "poop in flight". Unless you want to be covered in excrement you learn to fly a little offset from the bird in front of you so that you don't get smeared with the "exhaust". Makes it really hard to see where you're flying. Even birds can figure that much out.

Re:This is new?

[TheloniousToady]

Now that they've got that one nailed down, they should do a similar study to test certain long-held theories about bicyclist behavior in the Tour de France.

Re:This is new?

[antifoidulus]

So, it's a little bit of a behavioral science study...is saving energy why they do it, or is saving energy just a happy consequence?

Its evolution. Up until humans invented the SUV evolution tended to favor those that conserved energy.

Re:This is new?

[Nyder]

Right, because the guy should have remembered being taught it before he was born rather than so late in the game as when he was a child.

If only we had places where information could be stored and searched so people who think they've figured out something new can actually look to see if it's new.

Re: This is new?

[Em Adespoton]

Pigeons fly in V formation, as do crows. Actually, most birds that size do. Once you start getting smaller though, they flock, but don't do the V formation -- even with migratory birds. Once you're down to Juncos, Chickadees and Sparrows, they use more of a chaotic swarm and weave method to confuse predators -- but they also tend to hop from tree to tree, and don't fly long distances in the open.

What really confuses me is seagulls -- they flock like smaller birds and yet travel distances and have few (land/air) predators.

Re:This is new?

[Immerman]

>So, it's a little bit of a behavioral science study...is saving energy why they do it, or is saving energy just a happy consequence?

That seems like a question that would be *extremely* hard to answer in any way except "of course they do it because it saves energy". Assume for the sake of argument that it can somehow be proven that each individual bird flies as it does simply because it "feels good", or any other reason. The question still remains *why* does it "feel good", with the answer almost certainly being that evolution, that old non-sentient intelligence, sculpted the species in favor of some random mutation that made a more energy-efficient behavior "feel good". If there hadn't been a survival benefit to the behavior then it's unlikely it would have spread throughout the entire population.

It's like the adage says: "We don't like sugar because it's sweet, sugar is sweet because we like it". There's nothing inherently "sweet" about a sugar molecule, sweetness is a function of our brains interpretation of the signals from the chemo-receptors on our tongues. Sugar triggers a pleasure-response (sweetness) because our metabolisms can harness it as a rich energy source. Some distant ancestor who found sugar pleasurable consumed more energy rich fruits, and thus had more energy available and could out-compete their "sweet-less" rivals, and so the mutation spread throughout the population. Cats on the other hand are obligate carnivores whose metabolisms can't efficiently process sugars, and they lack the appropriate chemoreceptors to detect them - for them sugar is *not* sweet, and any mutation that changed that would rapidly fall out of the population because it would reduce the amount of fats and proteins consumed in favor of sugars that don't provide them much energy, making the afflicted individuals less competitive.

Research into the actual *mechanism* of the energy savings is still interesting though, we are only just beginning to understand the subtleties of flexible-wing flight. Dragonflies for example actually appear to use their front wings specifically to generate vortices (generally considered energy-sapping flaws to be minimized in fixed-wing aircraft) rather than producing thrust - the rear wings then interact with those vortices in a manner that provides more thrust than they could hope to generate directly. *Extremely* sophisticated energy-optimizing behavior that makes our fanciest aerodynamics technologies look like dog-paddling in comparison.

Re:This is new?

[AK Marc]

It isn't. Someone else indicated that the devil is in the details. It was known they did it and why, but the synchronization of flapping wasn't documented before.

Re:This is new?

[Russ1642]

The BBC would report on the link between sex and pregnancy if they had the chance. You try filling that many hours day after day with news and you'll end up reporting anything that happens, whether it's newsworthy or not.

Re:This is new?

[neoritter]

HEY HEY GUYS!!! I just discovered this great thing, when an apple falls from a tree and lands on the ground there must be some sort of force doing it! I think I'll call it fallivity. Yeah! And if you notice everything pulled down by fallivity falls at the same speed! 9.81 m/s^2 by my calculations!

Re:This is new?

[Sique]

Actually, no. You weren't taught that birds use synchronous wing-flaps to minimize the drag. You were taught that the V-formation of birds saves energy. But until now it seems that while for planes with fixed wings, where the air flow around the wing of the plane in front is still laminary enough to provide lift, it wasn't clear how this works with birds, whose wings cause the air to become turbulent. Now it could be observed that the synchronous wing-flap with shifting the flapping half a cycle from bird to bird allows the birds to have the wing in laminary air flow for most of the time and thus still keep the lift while still saving energy.

Basicly the birds not only fly in formation, they even fly in lockstep.

Re:This is new?

[Capt.Albatross]

point is you don't even need synchronized flapping to have benefit in a V formation, the reason for the V formation is not to have syncronized flapping, it's just an additional benefit

Have you ever been in a discussion where some Dunning-Kruger type tries to make a big deal over something that everyone else knows perfectly well, and who has failed to notice that the discussion has gone beyond that point? That's the role that you are playing here, as are the AC who started this thread and everyone who thought it was insightful.

The point of the study, and the thing that makes it newsworthy, is that it demonstrates that birds are capable of extracting energy from the unsteady flow created by flapping. Neither theory nor experiment showing that there is a benefit in steady flow settle the questions of whether it could, let alone is, being used by birds.

Unfortunately, sloppy science education has given a simplistic idea of how the scientific method works. Ideas do not get accepted merely because they are plausible.

       

Who is John Galt?

[noobermin]

I'm assuming then that the other birds are freeloaders.

Re:Who is John Galt?

[Kyont]

No, it's an anarcho-syndicalist commune. They take it in turns to act as a sort of executive lead-bird of the flight.

Old news...very old

[Nethemas the Great]

This has long been the explanation of why birds fly in an echelon formation and why throughout a migration the front ranks cycle from the front to the rear. As the leading rank of birds tire, the next rank takes over allowing them a bit of a rest.

Re:Old news...very old

[Cramer]

Incorrect. Watch some windtunnel tests. The vortex is behind the vehicle, not beside it.

A better word for this is "slipstream". You get close enough to have no air to push through. If your car has radar cruise control, following close enough to make a huge difference isn't too dangerous. (obviously on a highway where people aren't very unpredictable. and you're far better off following semi's.)

Re:Old news...very old

[Immerman]

Actually no, vortices and slipstreams are two related but very distinct concepts. Slipstreaming or drafting involves taking advantage of reduction in aerodynamic drag available from traveling within someone else's the slipstream or "wind shadow" - the region directly behind them where the fluid is moving at approximately the same speed as the object itself. Vortex surfing is a related phenomena, but rather than traveling within someone's slipstream to reduce your air speed and thus drag at the same ground speed, it harnesses the well-ordered turbulence (vortices) generated by the wings of the leading airframe in order to amplify the lift generated by your own wings. Completely different mechanism, and you're traveling within a completely different part of the leader's wake.

Re:Old news...very old

[deroby]

I'm assuming the parent is European (Renault Laguna) and we tend to talk about fuel-efficiency in liter per 100 km. Hence, a lower number actually means better efficiency in that context, hence the confusion.

FYI: My dashboard allows for these 3 options: MPG, l/100Km, Km/l. I actually like the km/l as it is much more interesting and also has better 'scaling', but sadly the l/100Km is most widely used in that respect that I'm pretty sure that if I would say I got 20km/l on a given trip I'd probably meet blank stares only =)

Re:Old news...very old

[fatphil]

To be pedantic, the drag increases with the square of the speed, and the power required to overcome that drag increases with the cube of velocity. (F~v^2 and F~P/v, so P~v^3.)

Not always

[Anonymous Coward]

In the northern hemisphere they actually fly in an A formation. Only in the southern hemisphere do they fly in a V.

Something to do with the Coriolis effect.

Re:Not always

[SJHillman]

I once saw a flock in F formation meet up with a flock in U formation. I think they might be the descendants of the birds I pissed off with a BB gun when I was a child.

This makes me optimistic

[Anonymous Coward]

about getting funding for *my* study on why dogs lick their balls.

now, maybe, there's DATA not guesswork?

[dltaylor]

Although this may not be the first time the airflow effects have been measured "in the wild", I cannot remember any previous instance.

There are a lot of things "everybody knows" that have never been verified. It doesn't hurt to run the experiments and perform the verification.

"Everybody knew" that time passed slower on a body moving faster; after all, Einstain had said so. Still, it wasn't until we put sufficiently accurate chronometers on spacecraft that we really knew it, because they did, in fact, show that the spacecraft experienced less time than the ground stations. Although surface installations are "orbiting" at about 1000 MPH (too easy with a 24 hour day and 24000 mile circumference), and are at the 1G level of the Earth's gravity well (also has an effect), the space craft are moving at about 16000 MPH (90 minute orbit at 100 mile AGL) and still at nearly the 1G level of the gravity well. That 15000 MPH difference shows up readily, even after the adjustment for gravity.

READ TFA

[noobermin]

Damn it slashdot, read the article. Although it doesn't claim explicitly that this is the first time this hypothesis has been tested, if anything, it appears this was just a study that verified that this hypothesis is correct. People already posited this and apply it for jets (see jets that fly in echelon formation), but, at least what is said and implied in TFA, this seems to still be something that is a matter of debate.

The lesser-known second cousin...

[gweilo8888]

Would that be Elbert Einstain you speak of?

Re:If you asked this question...

[Immerman]

I know it was the accepted theory as long as I've been aware of it, but how many experiments have actually been done to confirm that the theory does in fact describe reality? Without experimentation to attempt to disprove your theories there's precious little difference between science and philosophy. Even if several independently corroborating experiments were done early on, it may still be worth revisiting the question them from time to time - both to discover new details hidden to old technology, and to confirm that theoretical or cultural biases didn't color the earlier results.

Example - for decades it was accepted in chimpanzee behavioral research that the males were the dominant actors in seeking out sexual pairings, and there were several studies documenting the evidence of that. Recently researchers have re-examined the question and discovered that the females are at least as active in seeking out pairings, though they employ different strategies. Examination of video footage from the earlier research clearly showed the same behaviors - it was not some new phenomena, just something overlooked by earlier researchers because it didn't fit with their preconceptions.

Re:Really that hard?

[Immerman]

If you actually examine it and it's creation process a beaver dam or termite mound is actually a pretty impressive feat of engineering possessing many functional details at least as impressive as anything found in most human dwellings. Passive environmental regulation systems. Near-optimal structural layout based on environmental factors. And in the case of ants at least this is accomplished with near-zero cognitive problem solving abilities.

There's no shame in recognizing the brilliance of emergent systems, our own brilliant self-reflective minds and all we've created are themselves a manifestation of the self-arranging pattern. Also vortex surfing is a far more complicated and dynamic process than drafting. When drafting you simply travel within the slipstream of another, reducing your airspeed to roughly zero regardless of groundspeed, virtually eliminating aerodynamic drag. In vortex surfing you are instead leveraging the eddy currents created by the wings in front of you, amplifying the lift generated by your own. In a way Dragonflies do an even more sophisticated version of this in solo mode - in forward flight their front wings generate almost no thrust, instead generating a stream of powerful vortex "bubbles", which their rear wings can then leverage to generate considerably more thrust than having both wings in "thrust mode" could possibly manage.

It's a flock of birds, Jim, not rocket scientists!

[fygment]

Think like an ibis, goose, or ... hey ... a human pilot.

You want to fly with your buddies. Do you form:
  - everyone in line a single long line one behind the other? No because then all you can do is see is the person ahead of you and you are constantly surprised by their sudden accelerations (+ or -'ve) and you'd find yourself flying way slow and then way fast to catch up ... like cars in traffic.
- everyone line abreast i.e. beside each other stretching out to either side? No because then you have to keep looking from one side to the other trying to keep your distance from the next person and the same speed as them who are trying to keep speed with you so everyone ends up kind of rushing ahead then slowing down especially 'cause you can't see the partner two individuals away.
OR
- a vee formation where everyone gets behind and a little to the left or right of someone else? Yes. A leader will emerge if not already defined by the flock/squadron as top alpha creature/plane end everyone can easily see the individual in front to adjust to their speed and position, everyone can see approaching obstacles (in which case they can anticipate the movement of the individual they're following), and everyone can relatively easily take a quick look at the individuals all around them ... an excellent formation for creatures or aircraft flying together and trying to avoid collisions ...
AND _THEN_ .... distances get adjusted to maximize flight efficiency.

See how that works? Formation shape for safety from collision and then distances adjusted for flight efficiency.
It's why aircraft fly in such formations ... and it's why birds do it. Oh, and wolves, small herds, orcas, etc. Kind of anything travelling close with purpose .. even schools of fish are composed of a fractal pattern of 'v' formations ie. if not in front of everyone, the individual fish will get behind of, and to the side of the fish ahead of them ... if they didn't we would see fish CUBES instead of fish BALLS

Honestly, formations based on aerodynamics?! It's a flock of ibises, Jim, not rocket scientists!