Young bird, likely 3cy. Because of the missing orange on the bill I took it for a Masked Booby when I saw the bird. But unfortunately the bill color is only useful with adult birds. And since it apparently is the only criteria to distinguish the two from each other, I'll have to let pass as unidentified. When I look at the photos, however, I have to say that it does look like there is a slight cast of warm coloration to the lower mandible that does seem to be too dark for a Masked Booby, why, if I had to decide, I would now lean more toward a Nazca Booby in stead of a Masked.