Marine. Occurring in inshore,offshore,and, to lesser degree,pelagic waters. Breeds mainly on coastal islands,typically in areas of grassland,or other vegetation,but sometimes on cliffs or bare ground.
"Starts Oct." (HBW,1,p.254)
Transequatorial migrant.After breeding, most birds move north past Japan to winter off Aleutian islands,with some moving north of Bering Strait. Return route over central Pacific,some moving down west coast of North America. Apparently some regular movements into north Indian Ocean.