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?

[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?

[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?

[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.

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.

This makes me optimistic

[Anonymous Coward]

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

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.

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.

The lesser-known second cousin...

[gweilo8888]

Would that be Elbert Einstain you speak of?