Variable with populations,migratory or dispersive.
Movements of North Atlantic populations little known. Hypoleuca breeds Selvagens in northern summer, returning to colonies from February, departing end September; eadesi breeds Cape Verde Islands in northern winter, returning about November. Occurs around Canaries and Madeiran group, presumably feeding in Canary Current upwelling. Surprisingly few pelagic reports, most offshore from west and north-west Africa from 9°N-35°N and 13°W-25°W, especially off Morocco and Mauritania. Few scattered records far to west and north of colonies, mostly August–October, suggest post-breeding dispersal into central North Atlantic; single specimens of hypoleuca collected 320 km east of Nantucket, USA, September 1885 and in Azores May 1912; and single eadesi 160 km off Long Island, USA, August 1953 and at c. 42°N 66°W September 1959. Other pelagic records, not sub-specifically identified, span North Atlantic longitudinally, and include 6 more in Gulf Stream off New England; mostly singles, but small numbers 45°N-46°N, 37°-45°W October 1944 ahead of major storm front, 5 at 45-°N 43-°W in August 1957, and several at 40°N 9°52'W (west of Portugal) August 1962.
Southern hemisphere populations absent from vicinities of colonies chiefly May–September when dispersed at sea. Many dulciae from Australia migrate into tropical Indian Ocean where recorded all round north periphery west to Mombasa. Nominate marina of Tristan da Cunha and Gough Island winters within tropical South Atlantic, dispersing west to offshore South America, east almost to Africa; while limited northward dispersal indicated by scattered records at sea between Ascension Island and Angola (north to 6-°S) April–October.
Thanks to Birds of the Western Palearctic