Birds of North America says that the "most distinctive" of the Common Goldeneye's courting displays "are the Head-throw-kicks, where male thrusts his head straight forward, then lowers it to his rump with his bill pointed back past vertical, at which point he utters a single, grating call, thrusting his head rapidly forward (sometimes flicking it from one side to the other) while kicking water out with his feet." This picture shows the forward thrust stage; for the next stage, see http://www.pbase.com/image/148701267 .