This species inhabits coastal waters (Aspinall and Porter 2011). It is gregarious throughout the year, foraging in single- or mixed-species flocks up to 400 individuals (del Hoyo et al. 1996, Snow and Perrins 1998). It forages in the surf and offshore waters by plunge-diving or surface-dipping (del Hoyo et al. 1996, Snow and Perrins 1998, Jennings 2010). Its diet consists predominantly of small pelagic fish, but it may also take crustaceans such as prawns and shrimps (Urban et al. 1986, del Hoyo et al. 1996, Jennings 2010). During the breeding season, it establishes large, densely packed colonies on sandy patches on islands up to 200 m from the coast (Jennings 2010, Aspinall and Porter 2011). Colony locations are often protected by low vegetation and shrubs from predators, e.g. introduced cats and dogs, mice or Sooty Gull Larus hemprichii (Jennings 2010). The breeding season lasts from early May to July (Jennings 2010). The nest is a shallow scrape in the sand, which may gradually get deeper during incubation (Jennings 2010). Clutches contain one egg (Jennings 2010). After the breeding season, the species disperses out into the Indian Ocean; the details of its movement are poorly known (del Hoyo et al. 1996, Jennings 2010).