Black Ducks

I found this on Flyways.us: "The Black Duck is dusky brown with a paler head. The drake and hen look very similar except for their bills. The drake's bill is greenish yellow while the hen's bill is an olive green. Both sexes have a dark blue wing patch and a white under wing visible in flight. They both have a dark eye line" My conclusion; the first picture is the drake and the second is the hen.