The Early Morning Dance of Birds

The birds are gathered in flocks veining from the tide to 200 ft inland. When I try to disrupt their gathering they do the same dance every time.

One bird rises and then they all follow, swooping into line - a crescendo beat of wings. Half the flock heads over water and the other half inland, completing arches that meet and land simultaneously 100 ft away from where they were and where I now stand.