Nature Done Wright

On Mnday I wrote:

This is one last mystery from Yellowstone — a duck (left, above) seen on our trip that is considered rare for there this time of year.

What do you think it is?  Uncropped shot with Trumpeter Swans below.)

Photo by Lesley Hawkins. (Thanks, Lesley!)

Several folks said "Gadwall," so it must be true.  Congrats to all!