I recently watched about 2000 seagulls return to Felixstowe, (East Anglia, UK). They were fyling in skeins of about 20-30 birds and in many of the skeins there was a, larger than the others, gull flying at number 2 or number 3, as though it was training the leader of the skein.
Today, I was in the same place, again watching the birds flying home, but today it is incredibly windy and there was not a skein in sight. This time there was no discernable formation, they were flying in loose masses and circling and flying seemingly at random and were not noticably affected by the wind.
I don't particularly like seagulls, in any shape or form as I think they are bullies, having watched some of them gang up to knock a heron out of the sky, but their flying behaviour fascinates me.
Any chance you could explain the flying, please, especially the skeins with the larger bird following the front one?

the skeins and lack of them is easily explained: in the V formation each bird is located so that it profits from the wake vortex created by the one in front. The V develops because the wakes are strong near the wing tips, and useless behind the body. Thus, there are two good places to fly wind shadow behind a bird, which is where the next birds go.
Birds change positions in skeins for the simple reason that the first on does not profit from anyone, tires more easily, and will slip back to find an advantageous position.

by the way, you seem to suffer from what I call "nice bird syndrom"! I used to have this, too: one believes that birds, elegant and beuatiful as they are, should be "good guys". Remember, birds are theropod dinosaurs, with a long time evoliving for predation under their belt before some became specialized for other diets ;) Herons, by the way, are pretty nasty buggers, too. They eat gul hatchlings if they can get them, which explains why gulls do not like them very much.