Interesting. I never had really thought about the currents created by the flapping.

I wonder if they synchronize the flapping too?

Good read...

On a lighter note, they fly in V formation for V is pronounced as "We" whereas if the flew after one another, it would look like the character "I"...

Monday is over, I'm feeling creative again

Girish sir 

I had read about this long ago i dont know where but it was mentioned that due to flight over long distances the V formation increased flight efficiency of the birds, and also increased the attack angle so they didnt have to put as much effort to cut through wind in comparison to flying solo.
Also the leading bird will keep on changing and wont remain the same, when the leading bird gets tired another one replaces it from the flock.

I think its like flying in delta formation like a delta wing but what i dont understand is deltas are designed for speed and not efficiency so i must be wrong.
Is their angle of attack at a certain angle so to improve speed and efficiency?

addition to it...... The bird at the front has to put in more efforts than the ones at the back.... so they keep changing their positions ..... turn by turn they come in front.

not all birds fly in V

parrots fly in random formation

pigeons fly in random formation

the v seems to favoured by the geese types

logically

outer most needs to work harder, that too on the wing which is not being drafted. that is to say the right wing of the right most and left wing of the left most bird is most worked in the formation.

When you draft (technically cutting of wing tip vortex) it is win-win situation for both drafter and drafting bird. that's why the synergy. if you notice the shift is because the outer ones need to move inboard the formation.

There in another theory which says why leader keeps shifting. thoery postulates, birds remember the route selectively, meaning every bird remembers only a portion of the route (with adequate over lap), so when the leader starts to go wrong, the one who remembers the route replaces him, taking advantage of this shift the outer ones move inwards. (this theory has no proof though).

So much for formation flying

Saikat sir most migratory birds fly in this formation,  very few parrots( Swift parrots and Orange-bellied parrots) are migratory, and as for pigeons i dont know of any species that are migrtory, so you wont find them flying in this formation. Though domesticated pigeons used to fly for long distances but that was just to pass our messages from here to there.

Gusty sir why do you think migrtory birds fly in a V formation? its like deltas but they need to be fast to take advantage of this formation. Other than using drafts created by the leading birds wings do you think that if the leading bird catches a thin updraft of air, it will spread out from its wings uniformly and get distributed to the entire flock due to the V formation?