While watching raptors over Los Tarrales (Suchitepéquez, Guatemala) in January 2020, I got these record shots of the striking flight display of an adult Black Hawk-Eagle / Schwarzer Haubenadler (Spizaetus tyrannus). The (male?) bird was circling over its territory for a long period of time, constantly calling. From time to time it would slightly cock its tail in flight (see photo 3) and shake the wings like you would expect it from a wet bird. This video on youtube shows the behavior better (but the tail-cocking is missing).