Maps of the birds of the Western Palearctic Region

Oceanodroma leucorhoa
Pelagic, breeding on islands in burrows.
The taxonomy of this complex is confused. There are all dark-rumped populations on San Benito and Los Coronados islands; variable populations on Guadalupe Island, where both summer-breeding and distinct winter-breeding populations occur, and white-rumped populations nest elsewhere. Variation reported in vocalizations is of uncertain significance, but more than one species may exist on the eastern central Pacific coast.
The only name that certainly applies to the winter-nesting population is O. l. cheimomnestes.
O. l. leucorhoa Islands in n Pacific O. from Shumagin and Aleutian Is. and s coastal Alaska s to Baja Calif. (Los Coronados, San Benito); from Commander Is. s to Kuril Is. and n Japan (n Hokkaido); n Atlantic O. from s Labrador s to Newfoundland, Maine (Casco Bay) and Massachusetts (Penikese Is.); from s Iceland, Faroe Is. and Norway to n Scotland. Ranges at sea in Pacific from Mariana and Hawaiian is. s to Japan, Bonin Islands, Kiribati, Marquesas and Galapagos is., and in Atlantic s to e Brazil, S. Africa and Mediterranean Sea.
O. l. socorroensis Guadalupe I. Ranges at sea n to s California.

Oceanodroma monorhis
Pelagic, breeding on islands in burrows.
Is. in n Pacific O. off Japan (off n,ne Honshu and n Kyushu), s,w Korea and e China (off Shantung), probably Ryukyu Is. and small is. off ne Taiwan. Ranges at sea to tropical Indian O. (n to Arabian Sea and Ceylon) through Strait of Malacca and Greater Sunda Is. A few birds captured ashore in the nw Atlantic from Madeira to Great Britain are vocally and genetically closer to this species than to sympatric O. leucorhoa and their status is not clear.
O. monorhis is sometimes treated as a race of O. leucorhoa, but differs
in calls, proportions and genetic traits.

Oceanodroma castro
Pelagic, breeding on islands in burrows and rock crevices.
Is. in Pacific O. off Japan (Hide Shima, possibly Sangan Hima), Hawaiian (Kauai, possibly Maui) and Galapagos is.; Atlantic O. (Azores, Madeira, Salvage, Cape Verde, Ascension, St. Helena, and possibly São Tomé, also Is. Farilhões off c Portugal). Ranges at sea in Pacific O. near breeding grounds and to Phoenix Is., rarely to s or c California; in the Atlantic from
e U.S. and British Isles s to w Africa.