Anas platyrhynchos – mallard duck, Boulder, Colorado, March, 2024. I am no great fan of mallard ducks (we have almost as many as we have Canada geese, but at least they seem to be housebroken). This one, a male, must have had especially clean, new feathers, because he clearly shows the green, iridescent coloring on his head. That is, the coloring is not due to pigment, but rather interference colors owing to layering in the feathers. You can tell because the color faces you, but is absent elsewhere. Mallards also show bluish iridescence farther back, but that is not visible in this picture. Like many things, the green head looks better in life than in a photograph, but a photograph is the best I can do.
