Behaviour Most populations are migratory and dispersive^{2, 3} and abandon their breeding sites at the end of the breeding season to overwinter at sea³. Its detailed migratory movements are largely unknown however¹ and some populations in the Indian Ocean are entirely sedentary or only partially migratory³. The timing of breeding varies geographically, most populations breeding annually in groups of 2-30 pairs (sometimes up to 400-2,000 pairs)¹ that are not strictly colonial but involve solitary pairs congregating in suitable habitat³. When nesting the species often associates with nesting Sterna fuscata or Sterna bergii¹. After breeding the adults and newly fledged young leave the breeding colonies in loose flocks² and migrate alone, in small groups of 10-12 individuals or more rarely in larger groups of up to 200 individuals³. Outside of the breeding season the species is thought to occur singly². Habitat The species inhabits offshore tropical and subtropical seas^{1, 2}. Breeding It breeds on the periphery of vegetated coastal and continental³ coral, rock or rubble islands and beaches^{1, 2, 3}, volcanic stacks and exposed reefs³, foraging inshore and up to 50 km offshore (although mostly within 15 km of land)¹ and feeding from the surface of the water or up to 20 cm below it². Non-breeding Away from the breeding grounds the species is entirely pelagic and often associates with patches of macroalgae (e.g. Sargassum spp.) or flotsam³ which it uses for perching¹. Its marine distribution is therefore linked to small- and medium-scale oceanographic features where water circulation aggregates such floating matter into patches³. Diet Its diet consists predominantly of squid and surface-schooling fish less than 6 cm long as well as crustaceans and occasionally aquatic insects¹ or molluscs². Breeding site The nest is a scrape or depression in shingle or sand² that may be freshly excavated or re-used from a previous season². Nests are placed in a variety of concealed locations^{1, 2} around the rim of oceanic islands¹, including natural cavities amongst rocks or coral rubble, in vegetation^{1, 2} (up to 75 % ground cover)², in a crevice or cave up to 1.5 m deep, under a cliff ledge or on the ground beneath low bushes or shrubs². The species is not strictly colonial but solitary pairs usually congregate in suitable habitats³ with neighbouring nests spaced according to nest-site availability (usually 1-5 m apart, minimum 30 cm)¹. Management information The species will become habituated to human presence in sites exposed to long term visitation, especially where human movements are predictable, groups sizes are kept consistent and human behaviour is reliable³. Additional measures to reduce human disturbance of nesting colonies includes the erection of barriers and signs, the provision of walkways, and the supervision and education of vistors³.

TCTATACTTAATTTTCGGTGCATGAGCCGGTATAGTAGGTACTGCCCTTAGCTTACTCATTCGTGCGGAACTAGGCCAACCAGGGACCCTTCTAGGAGACGACCAAATCTACAATGTAATTGTCACCGCCCACGCCTTCGTAATAATTTTCTTCATAGTAATGCCAATTATAATTGGTGGTTTCGGAAACTGATTAGTACCACTTATAATCGGTGCCCCCGACATGGCATTCCCACGCATAAACAACATAAGCTTCTGACTACTACCCCCATCATTTTTACTTCTTCTAGCCTCCTCCACAGTAGAAGCTGGGGCTGGAACAGGATGGACCGTATATCCTCCCCTAGCCGGTAACCTAGCCCATGCCGGAGCTTCAGTGGACTTAGCAATCTTCTCCCTCCATCTAGCAGGTGTATCCTCTATTTTAGGTGCTATCAACTTCATCACCACAGCCATTAACATAAAACCTCCTGCCCTCTCACAATACCAAACTCCACTATTTGTATGATCCGTACTTATTACTGCCGTCCTACTACTACTCTCACTCCCAGTACTTGCTGCCGGCATCACTATGCTATTAACAGATCGAAACCTAAACACAACATTCTTCGATCCTGCCGGAGGTGGTGACCCAGTACTATATCAACATCTCNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
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Red List Category

Red List Criteria

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The species is vulnerable to the effects of oil spills and is highly vulnerable to the accidental introduction of domestic cats Felis catus to offshore breeding islands³. It has also been known to abandon breeding colonies when subject to severe human disturbance (although at sites exposed to long-term visitation it may become habituated to continuous and predictable human presence and activity)³. Utilisation Eggs are harvested for subsistence in the Bahamas and the West Indies, and eggs and chicks are harvested on some islands in the Pacific by local residents and coastal shipping crews³.