American and Eurasian Wigeon Variations

The American Wigeon male in breeding plumage is a distinctive duck, with a light crown, wide dark stripe on the side of the head extending back from the eye, and a warm flank color.

A close-up front view shows the black line around the base of the bill:

The male Eurasian Wigeon is equally distinctive, with a striking uniform rufous color on the head and lighter gray on the flank, becoming more pink at the shoulder. A small area of green near the eye is sometimes seen and does not indicate a hybrid with the American. Note the absence of a black line where the bill joins the face on the Eurasian Wigeon.

We sometimes see male wigeons that show characteristics of both American and Eurasian Wigeons, likely representing natural hybrids of the 2 species. Sibley and others show that such hybrids are variable. They usually have a two-tone face like the American, but instead of a green iridescence we see a warm brown or rufous color, and variable coloration on the flank. The bill may show a black line at the face.

The male wigeon below shows a rufous brown stripe on the face. He lacks a strong black line where the bill joins the face, and has a mix of gray and rufous on the flank, all suggesting he may have some Eurasian Wigeon DNA:

Here's another shot of the above bird, with an American Wigeon close by for comparison. Alternatively, we may just be viewing an eclipse male American Wigeon that in well along in his pre-alternate molt:

Lastly, sometimes when the light strikes the face at just the right angle we can see a beautiful golden bronze color instead of green, a variation in iridescence and not the expression of brown pigment:

While there is no confusing the male Eurasian Wigeon from the male American Wigeon, the females of these species look quite similar. After consulting multiple sources I came up with this set of criteria that might help in picking out a female Eurasian from a flock of American Wigeons. Now I'd just like to find a female to photograph!