Looks like a female Comb Duck or Knob-billed Duck. It's hard to tell which species it is at this angle, and neither species was listed in the species list that was posted for the Bronx Zoo last year. The males of the two species are easy to tell apart because the male Knob-billed Duck has light-colored flanks while the male Comb Duck has dark or black flanks. This is either a female or an immature, so I can't say for certain. Because most of the other animals in that building are Old World species, I'm inclined to say that this is a female Knob-billed Duck.
