The Stejneger’s Petrel breeds only on the outer island, Alejandro Selkirk, of the Juan Fernandez Archipelago in Chile. It is a smaller, shorter-winged Pterodroma of the “Cookilaria” subgenus, and it has in the past been considered conspecific with either Cook’s Petrel (Pterodroma cooki) or Gould’s Petrel (Pterodroma leucoptera). Morphological, plumage and biogeographical considerations all support species status. As its Scientific name implies, this Cookilaria has a long and thin bill, it also shows a well marked “M” pattern on the upper side, and a distinct blackish hood which contrasts with the blue-grey back. The population has been estimated at 131,000 breeding pairs, although recently estimates have been lower. The IUCN lists this petrel as Vulnerable. Although restricted to one small island as a breeder, in the non-breeding season this is a trans-equatorial migrant. It spends the non-breeding period in the temperate north pacific, showing a tendency to use the Asian side of the Pacific such as offshore from Japan. To the east it is a very rare migrant offshore in California and Hawaii.