The individuals varied in how much black there was on the head and also the amount of orange at the base of the bill.
It was interesting to watch their various strategies when a wave approached. Sometimes they swam up and over the wave, other times they dove through and emerged on the other side, and occasionally they took to the air and flew up and over.
Here are two shots of birds emerging from a dive through the waves.
And two more of birds in flight. It was a great chance to see their wing patterns — note the bold white wing stripes.
I don't know how long these birds will stay in the area, but if you're at Doran Beach, it would be worth looking for them!