The Red-breasted Mergansers were far more active than the Common Eiders we saw. They were constantly diving for food, but they also seemed to be showing a lot of aggression towards the Eiders - without any obvious provocation.
This merganser was really making himself appear large and intimidating.
For the most part, the Common Eiders just watched dispassionately. They appeared unimpressed.
One eider finally reacted, showing himself to be larger and stronger looking than the merganser who started it all.
In this shot, it looks like he's dancing a ballet!