Last time I was in the Galapagos, this booby was classified as "Masked booby" (Sula dactylatra) which occur e.g. in the Western Pacific. Nowadays, it has been found that this bird is a separate species, named after the continental plate where it occurs: Nazca booby. This species breeds only in the Galapagos and on some islands off western Mexico. This particular bird nests on Genovesa, one of the northernmost Galapagos Islands.