$Pterodroma externa tristrani Mathews,1931,Bulletin of the British Ornithologists' Club,52,p.63. (Tristan da Cunha).
Marine and highly pelagic,otfen in areas of upwelling.Rarely approaches land except at colonies.Breeds on oceanic islands,typically occupying higher parts of gentle slopes,typically with low vegetation.
Transequatorial migrant,ranging over tropical and subtropical waters of northwest Pacific,north to Japan. Anundant in central Pacific May-November,where some birds occur all year round.