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A couple of flocking thoughts , without much consideration on my part, so take
them with a grain of salt.
1) The 'leading edge' of the skein can be expected to be the least turbulent
position in the formation.
2) Theoretically, the bird in front suffers highest drag because induced drag
is reduced for all other birds in the formation, plus (if appropriately spaced)
they are flying in the upwash from the preceding bird's wingtip vortex and
therefore require less power to maintain altitude.
2a) To the best of my knowledge, no effort to test or quantify #2 above using
real birds, has been successful.
3) As you know, a bird loses significant weight during a long flight, first
as it burns off fat during the early portion of the flight, then as it
metabolises and burns off muscle mass later in the flight. Consequently, all
the birds' airspeeds will gradually tend to increase during the course of a
flight. I would suggest perhaps that on average, due to mass variations, half
the birds in the formation are flying at a slightly slower speed than they
would wish, and since within a species the lighter birds tend to be faster --
possibly when the leader tires, it is replaced by one of the other birds that
is lighter than average, therefore having generally both a faster beat
frequency, a faster airspeed, and an urge to shift to a more comfortable gait
(the more comfortable position).
4) I done said more than I know about this.
> , but why would the Flying
> > V's [skeins?] opt for the morew turbulent leading
> > edge?
> , and one of the others overtakes it. Then the rest settle into the most
> comfortable positions.