Brant

Today, down at Fulton Ferry, I saw a large flock of about 100 Brant flying over the East River. Brant don't fly in formation like Canada Geese; they're more like a crowd of birds flying in the same direction. What interested me was that even though they have no leader, they all flew in the same direction, circling over the river a few times before they landed in it, and, more interesting, they all beat their wings in unison and glided in unison. Their timing was precise; there was no delay from the front of the flock to the back of the flock. They all stopped beating their wings at the same moment and started flapping again at exactly the same time.

You'll see lots of bird species doing this, as if there is a group mind, but they seem to fly in tighter formations and I don't know if they have the same marching band precision these relatively big birds achieve. How do they do it?

Later, on the lawn, I saw about 45 Brant grazing on the brown grass of Empire State Park, With them was one Canada Goose, huge next to them, wandering among the flock and seeming completely out of place.