Mergus squamatus.
Pair, male in eclipse plumage on the right. The water in this exhibit is very deep, and holds a variety of stugeons which can be seen through windows indoors (opposite the penguins).
@Summer Tanager I had to look it up - the clue is the black feathers on the wings. Incidentally, posts in the Antwerp thread say that the pair produced 3 chicks this year.
That's great news about the chicks! This is a beautiful species of merganser and I'm glad that it's becoming more popular in zoos on both sides of the Atlantic!
