They do this all the time. It’s a territory thing.
One Egret wants the same spot another already has. It doesn’t matter that there are 300,000 + acres around here.
They just try to land right on top of the other one. Of course he moves. In a few minutes he may come back and do the exact same thing to reclaim the spot.
All during this the Anhinga sits with wings out spread, never moving. It had nothing to do with him.