Good question. I don't remember what the sign on the cage said, but the bird guide info on line says that the Blue-billed is the only one with blue on its bill, so it must be.
This exhibit is also supposed to have Cotton Top Tamarin and Red Footed tortoise which I did not see on my visit. And yes these are blue billed curassows.
Those are Northern Helmeted Curassows (nominate subspecies) in the Pheasant Aviaries. The zoos has Blue-Billed Curassows both in this enclosure and in the South American walk-through on the second floor (still represents at least two pairs).
I don't know how common they are but I've seen the species both here and at Smithsonian.
