What are the three mergansers in the above photo up to, and why does the one on the right look as though he’s about to charge at the others? They’re engaged in a pair-bonding display, a competition of sorts. They’re trying to win the praise of a female merganser off to the side (just out of the picture).
There’s a lot of head-shaking and strutting about during these pair-bond sessions. The birds shake their heads from side to side, rear back the necks, raise the front of the bodies out of the water, and give out a rolling, frog-like croaking sound all in an effort to outdo one another, and of course, impress the ladies.
Note that in the above photo, and again below, there’s another female who seems to be watching the events, but seems little interested in participating.
This shaking, strutting and chasing about will go on until the female selects the male she prefers to spend time with. The pair will spend the remainder of the winter together while the rest of the crew pursue other females until they themselves are bonded.
The pairs will, throughout the rest of the winter, reinforce the bond with occassional displays by the male until its time to head off to the breeding grounds. Already bonded upon arrival, they will waste little time getting down to the business of nesting.