Marine & highly pelagic. Usually occurs far from land except at colonies. Breeds on barren off-shore islands,occupying a wide variety of habitats,ranging from cliffs and boulder scree to sandy shores
"Starts Apr/May" (HBW,1,p.250)
Mainly absent from breeding grounds September or October to March.Disperses over tropical and subtropical waters.Pacific birds probably move into Central & East Pacific,and also the Inidan Ocean, west to the Maldives. Atlantic birds move mostly in West & South Atlantic,with a few reaching South Africa.Vagrant to Australia,British Isles and western Mediterranean.