It’s always nice when similar species pose side by side for direct comparison. These two wigeons, Eurasian on the left, American on the right, were engaged in some synchronized grazing. The female Eurasian Wigeon is a warm brown color, compared to the colder gray/brown tones of the American.
Male wigeons are easier. The Eurasian has a rusty head with just a hint of green behind the eye, and a clear demarcation between the pinkish breast and the gray vermiculated sides.
Ethical Birder 
Nice photo comparisons! I like the new photo you have as a header, I haven’t been to your site in a while so maybe it’s not so new.