Species fact sheet by Global Register of Migratory Species - www.groms.de

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Makes long distance, non-stop migrations of at least 4000 km over open ocean. After breeding adults and juveniles gather on Alaskan coast prior to migration; juveniles migrate unaccompanied by adults. Occurs on passage on pribilof, Aleutian, Hawaiian and Marquesa Is. Failed breeders start migrating S from late Jun, successful breeders and juveniles from early Aug; adults and juveniles arrive in wintering areas late Aug to early Sept, and adults depart early May. During moult on wintering grounds c. 50% of adults become flightless for c. 2 weeks. Immature birds spend all of their pre-breeding years on wintering grounds. Migrate in small flocks. Shows no diurnal pattern in timing of departures. Possibly birds wintering in C & S Pacific overfly Hawaiian Is on both migrations, flying distances of over 6000 km, relying on aid of tailwinds.   (del Hoyo J, Elliott A, Sargatal J (eds), 1996)

• digitised by GROMS, after del Hoyo J A Elliott; J Sargatal (eds) (1996) - www.hbw.com,
• Copyright: GROMS/BfN - www.groms.de
  
  (A digitised version of this map is published in GIS shape format on the GROMS CD).