Where do you go to my lovely

Now here is a mystery that I hope someone further along the coast can solve. Its like this, ever since we have been here we have noticed large flocks of seagulls heaing south every evening at dusk. We have christened them the “squadrons". There can be anything from a handfull to a few hundred birds in any one formation. Question is where do they come from and where are they going to. You never seem to see gulls in large numbers down on the playa so we are assuming theses birds live inland. If they spend their days or nights near you please get in touch as we would love to know. We have thought about giving chase but that would be crazy would'nt it? It’s interesting that they fly in a V formation too, never knew that until we came here. Flying in a V formation helps the birds in covering long distances efficiently. All the birds except the first are flying in the upwash from the wingtip vortices of the bird ahead. The birds in the formation take turns flying first. A little upwash assists the bird to support its own weight in flight in the same way a glider can climb or maintain height indefinitely in rising air. In V formation of 25 members, each bird can achieve a reduction of induced drag by up to 65% and as a result increase their range by 71%. The birds flying at the tips and at the front are rotated in a timely cyclical fashion to spread flight fatigue equally among the flock members. The formation also makes communication easier and allows the birds to maintain visual contact with each other. Nature never ceases to amaze me.