Migrating Geese
Migrating Geese
[Caption above the panel:] Understanding Migration of Geese
[20 geese are shown flying in a typical migratory V-formation. As they are shown in silhouette it is not possible to determine if they are seen from above or from below.  They are flying toward the top of the image with the first goose close to the top in the middle of the image.  There is one head goose, and then there are 7 geese in the left arms and 9 geese in the right arm. Behind the left arm there are two stragglers that are not in line with the others, but closer to the middle than those above and not as close to each other as the rest but still flying in the same direction. Finally there is one goose at the bottom right corner flying at a 45 degree angle away from the other to the right. The first goose is flapping its wing, which is also the case with six other geese, no. 4 and 6 in the left and 3, 5 and 6 in the right arm as well as the middle of the two in the rear towards the middle. The rest are soaring with straight wings and all of these look the same except no.  7 in the right arm which has two tails, which both goes ahead of the wings, making it look like a plane with two engines. The head goose and 5 of the 9 geese in the right arm as well as the one bottom right are labelled with and arrow pointing to them from the label. The front goose has the label in front to the left, the other have it in front to the right, except the second last in the arm which has the label inside the V and one flying away which has the label right above it. The two behind and right of the left arm have one label behind them with two arrows from the label pointing at both geese. There is a thick curvy line in front of geese no. 3 to 5 in the left arm. In front of that line is a thinner broken line. In front of this is a label written with the same curvature. There are two areas surrounded by dotted lines. The first one is behind the last of the left arms geese, extending in the same direction for a distance of about two geese. It has a label above and left with and arrow pointing to it. The other area is in the middle of the V forming a loose triangular structure with a label inside.] Head goose:  Head goose (4 th in line to the British throne) Right no. 1: Quarterback Right no. 3: Comptroller Right no. 5: Migration abort goose Right no. 7: Twin-engine model Right no. 8: CIA informant Bottom right corner: Kevin Behind center: Backups In front of left no. 3-5: Shock front Empty area behind left arm: Missing valence geese Empty area in center: Stealth cargo being escorted

Migrating refers to the changing of a habitat, which happens every year with birds like geese that travel long distances to avoid cold seasons and get back to the food in the summer time. When geese fly to their new habitat, they tend to fly in a very clear V formation . The V formation improves the efficiency of flying birds, particularly over long migratory routes. All the birds except the first fly in the upwash from one of the wingtip vortices of the bird ahead. The upwash assists each bird except for the "leading" one in supporting its own weight in flight, saving them up to 20% of the energy needed.
It should be noted that geese do have family structures with adult geese in "alpha" positions, but not a strict ranking order. An individual's position in formation flights is coincidental and constantly changing, so that the goose at the point of the formation can pull back and rest in the V wings while others "lead" the swarm. Popular earlier beliefs about an "alpha goose" heading a formation for the entire flight is a myth, easily disproved by watching geese formations in flight.
This comic shows such a formation with 20 geese, with several geese and areas in the V formation labeled, giving different roles to the geese and assigning these areas a new meaning. See the table below .
Apart from a "twin engine" goose in the bottom right arm of the V the only part of the formation that would not normally be seen is Kevin, who flies off at a 45-degree angle. In that direction there is no aerodynamic help from the other birds, and in the title text the rest of the geese also exclaim, "Dammit, Kevin" when he (again?) tells them that he has a great new idea for a migration (maybe referring to the new direction). This is either a reference to the fact that migrating birds manage to consistently arrive in the same general area every year, or to the way that vacations are sometimes suggested (by humans): "I thought of an idea for a vacation..." This was only the second time the name Kevin was used in xkcd for a fictive person, see more in this trivia .
[Caption above the panel:] Understanding Migration of Geese
[20 geese are shown flying in a typical migratory V-formation. As they are shown in silhouette it is not possible to determine if they are seen from above or from below.  They are flying toward the top of the image with the first goose close to the top in the middle of the image.  There is one head goose, and then there are 7 geese in the left arms and 9 geese in the right arm. Behind the left arm there are two stragglers that are not in line with the others, but closer to the middle than those above and not as close to each other as the rest but still flying in the same direction. Finally there is one goose at the bottom right corner flying at a 45 degree angle away from the other to the right. The first goose is flapping its wing, which is also the case with six other geese, no. 4 and 6 in the left and 3, 5 and 6 in the right arm as well as the middle of the two in the rear towards the middle. The rest are soaring with straight wings and all of these look the same except no.  7 in the right arm which has two tails, which both goes ahead of the wings, making it look like a plane with two engines. The head goose and 5 of the 9 geese in the right arm as well as the one bottom right are labelled with and arrow pointing to them from the label. The front goose has the label in front to the left, the other have it in front to the right, except the second last in the arm which has the label inside the V and one flying away which has the label right above it. The two behind and right of the left arm have one label behind them with two arrows from the label pointing at both geese. There is a thick curvy line in front of geese no. 3 to 5 in the left arm. In front of that line is a thinner broken line. In front of this is a label written with the same curvature. There are two areas surrounded by dotted lines. The first one is behind the last of the left arms geese, extending in the same direction for a distance of about two geese. It has a label above and left with and arrow pointing to it. The other area is in the middle of the V forming a loose triangular structure with a label inside.] Head goose:  Head goose (4 th in line to the British throne) Right no. 1: Quarterback Right no. 3: Comptroller Right no. 5: Migration abort goose Right no. 7: Twin-engine model Right no. 8: CIA informant Bottom right corner: Kevin Behind center: Backups In front of left no. 3-5: Shock front Empty area behind left arm: Missing valence geese Empty area in center: Stealth cargo being escorted
