On my March 18, 2016, trip to the Ridgefield NWR, I spent some time observing a group of about a half dozen American Coots, one of which appeared to be a real bully. After a couple of charges by the bully bird I realized that when the bird ducked its head down toward the water with outstretched neck, it was about to charge. I caught him doing his charge toward another Coot in this image.
Canon 5D Mark III, 1/1250, f4, ISO 400, 500mm, 3:02 p.m.