General: Dark gray upperparts. Pale gray throat and breast. Mottled white and pale gray underparts. Yellow eye. Thick, pointed yellow bill. Sexes similar. ??? inches in length.

Adult Alternate: Has two facial plumes, one behind the eye and one behind its bill. Short, upright horn at base of bill.

Adult Basic: Has less distinctive facial plumes and no bill horn.

Immature: Similar to adult basic, but lacks facial plumes and has a darker bill and eye.

Open ocean; pelagic.

Nesting

1 white egg, often spotted. The eggs have a 39-52 day incubation period. Fledging occurs in 48-55 days. These birds begin breeding when they are 3-5 years old. The nest is a deep burrow in a grassy or timbered sea facing slope. Nests in colonies, which are often quite large.