When seeing a flock of geese or any other bird migrating south for the winter you often see birds flying in a V formation. This V formation also known as an echelon is seen because of one lead bird and two lines of birds equally spaced behind them. There are some reasons of the V formation which can be explained through two science based theories. The first theory is about the birds conserving energy on long flights while the other theory is about communication between the birds.
When consuming energy on long flights some birds in the flock have it easier than others. When a bird flaps its wings, “each downward push of the wing creates a vertical vortex (swirl) in the air trailing the bird (flyingcircusofphysics.com)”. If a bird following behind a lead bird positions itself in the perfect spot of the vortex that gives an up-flow, the bird catches onto the flow and is able to glide along without much work to stay in flight. A solo bird not flying in a formation receives some drag from the air hitting the wings making the birds work much harder than if the birds flew in a flock. When being in the V formation, “flapping the wings less often means that the bird's muscles do not work as hard and its heart rate drops. As a result, the bird does not tire as quickly and is able to fly farther (aerospaceweb.org).” If each bird in the flock positions itself properly behind other birds in the flock, many of the birds will not have to work as hard as others. To be in the up-flow of the bird in front, the trailing bird needs to be off to the side of the bird in front of it. When each bird in the flock is in this positioning, it creates the V-shape. There are some negative factors of the V-shape however. The leading bird and the last two trailing birds have to work harder than the birds in the middle of the flock. Once the lead bird gets tried it drops back in the formation allowing other birds in the flock to take the lead position until they themselves get tired. The last two trailing birds work harder because they get some drag on the side that does not have a bird behind them. The two last trailing birds also switch positioning with birds in front of them once they get tired. This theory however does not always work as stated from the article, “Organized Flight in Birds,” “close formation flight might provide the advantage of a turbulence-free zone which is like the vortex that gives an up-flow, behind a bird ahead, but that would seem to apply only if the birds flew immediately behind the bird in front.” It is especially hard to be in the correct position in the flock to catch the up-flow because the spacing in the V formation is often uneven, making it harder to fly in the formation.
The second theory of why birds fly in a V formation is because of communication in the flock. The formation allows the birds to see everyone in the group. Scientificamerican.com states that, “Knowledge of birds visual axes, "blind spots" and field of vision have allowed researchers to pinpoint the best locations for birds within a flock to maintain optimal visual positioning.” Because of the way geese’s eyes in particular are located on their head, the V formation allows them all to see where everyone in the flock is located making sure not to lose one of the birds in the flock on long journeys when migrating. The lead bird in the formation has a major role in the flock leading all the other birds. But this lead position often changes as the birds become more tired in this position compared to the middle of the flock where there is more of an energy advantage. This formation can also be seen in military aircraft flying. The aircrafts however are usually spaced too far apart to gain the benefits of not having as much drag unlike the birds that can get closer together that can have a slight energy advantage. This V formation however is useful because it allows them to view all of the other aircrafts when flying.
"Aerospaceweb.org | Ask Us - V-Formation Flight of Birds." Aerospaceweb.org | Reference for
Aviation, Space, Design, and Engineering. Web. 16 Oct. 2011.
This is a website explaining V formation of birds. This source was useful to me because there was more explanation of the theories behind it. The website also includes many photos and diagrams showing what happens when the bird’s wings catch air and the importance of the bird’s position in the formation. I thought the source was pretty credible. The site was from a science website showing that it was credible and the information given on the site went with the other information I found.
Bajec, Iztok Lebar (01/01/2009). "Organized flight in birds". Animal behaviour (0003-3472), 78 (4), p. 777.
This is an article that I found online from the University of Wyoming’s library about organized flight in birds. This source was useful to me because it gave me more information behind all the theories. This article also gave another view on why the V formation may not allow birds less drag because of the distance between the birds in the formation. This article is peer reviewed which makes it credible. There was a lot of research and information behind all of the statements in this article making the information reliable.
"Why Do Migratory Birds Fly in a V-formation?: Scientific American." Science News, Articles
and Information | Scientific American. Web. 16 Oct. 2011.
This site discusses briefly why migratory birds fly in a V formation. This site was useful because the information given to me matched with the other things I found with my other resources but also gave me more information on why they fly in the V formation. This site is credible because the information is reliable and the article on the site was written by a biologist in Tennessee.
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