What is the lift generated by geese or other birds flying in formation?

[Attack_from_the_3rd_dimension]

I got this glurge about working together that references geese and the lift they generate by flying in formation, thus decreasing the effort of individual birds. I reproduce this below:

Lessons From the Geese

As geese flap their wings, they create an uplift for the bird following. By flying in a V formation, the whole flock adds 71% greater flying range than if any bird were to fly alone.

Whenever a goose falls out of formation, it suddenly feels the drag and resistance of trying to fly alone, and quickly gets back into formation to take advantage of the lifting power of the bird immediately in front.

When the lead goose gets tired, it rotates back into formation and another goose flies at the point position..

When a goose gets sick or wounded or is shot down, two geese drop out of formation and follow it down to help and protect it. They stay with it until it is able to fly again or dies. They then launch out on their own, with another formation or catch up with the flock.

I’ve snipped the anthropomorphic bullshit, leaving only the statements asserted as fact. If anyone can cite information regarding lift generated by flying in formation and changes in range I’d appreciate it.

[Philster]

Wing tip vortices.

http://www.warren-wilson.edu/~physics/PhysPhotOfWeek/20060929GeeseV/index.html

http://www.niquette.com/puzzles/gooses.htm

Wingtip Vortices

Wingtip vortices

[Alka_Seltzer]

Flying in formation results in the trailing birds experiencing less drag, not more lift. Flying in formation is much more efficient, they take turns to lead the group. Cyclists in a peloton make use of the same trick, the wiki article says up to a 40% reduction in drag.

Edit - This wiki article suggests 25 geese in a v formation can increase their range by 71%. It says the benefit is due to increased lift, not just slipstreaming as I said above.

[Chronos]

If the birds are in level flight, then the total lift force is equal to their total weight, full stop. The amount of effort needed to generate that lift may vary, but the lift itself does not.

[Attack_from_the_3rd_dimension]

Thanks. I appreciate your efforts.