Alfred Newton

“ The scaup-duck has considerable likeness to the pochard (q.v.) , both in habits and appearance; but it much more generally affects sea-water, and the head of the male is black, glossed with green; hence the name of “Blackhead,” by which it is commonly known in North America, where, however, a second species or race, smaller than the ordinary one, is also found, the Fuligula affinis. The female scaup-duck can be readily distinguished from the dunbird or female pochard by her broad white face. ”