A birder once told me that the Gadwall was a fairly plain grey duck; I assume that he'd seen them only at a distance since close to the male has most delicate wavy lines and shell-like patterns . . .
. . . with russet, black and white as well as rich chocolate brown and mid-brown edged with pink-beige. The Gadwall is common in northern regions of Europe, Asia and America.
Like most northern ducks, the female is plainer than the drake, similar to female teal or mallard, distinguished by her smaller size and orange-edged bill. She also has delicately-edged feathers.
Gadwall pair, duck and drake
The male Gadwall can be distinguished from the male (Green-winged/Common) Teal at a distance by his black rump rather than white
The juvenile male looks like the female until he grows adult plumage