Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Charadriiformes Laridae

Scientific Name: Gygis alba
Species Authority: (Sparrman, 1786)
Common Name(s):
English Common White Tern, Fairy Tern, Common White-Tern, Angel Tern, White Tem, White Tern
French Gygis blanche
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Ekstrom, J., Butchart, S., Calvert, R.
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Previously published Red List assessments:
2009 Least Concern (LC)
2008 Least Concern (LC)
2004 Least Concern (LC)
2000 Lower Risk/least concern (LR/lc)
1994 Lower Risk/least concern (LR/lc)
1988 Lower Risk/least concern (LR/lc)

Geographic Range [top]

Range Description: The Common White Tern has a distribution across the tropics of the world, being found year-round on islands in the south Atlantic Ocean, the Indian Ocean, and the western and central Pacific. It is also a seasonal visitor to islands in the south-central and eastern Pacific off the coast of Mexico1.
Countries occurrence:
American Samoa (American Samoa); Australia; Bangladesh; Brazil; British Indian Ocean Territory; Chile; China; Cocos (Keeling) Islands; Colombia; Comoros; Cook Islands; Costa Rica; Fiji; French Polynesia; Guam; India; Indonesia; Japan; Kiribati; Maldives; Marshall Islands; Mauritius; Mayotte; Mexico; Micronesia, Federated States of ; Nauru; New Caledonia; New Zealand; Niue; Norfolk Island; Northern Mariana Islands; Palau; Papua New Guinea; Pitcairn; Réunion; Saint Helena, Ascension and Tristan da Cunha; Samoa; Seychelles; Solomon Islands; Tokelau; Tonga; Trinidad and Tobago; Tuvalu; United States; United States Minor Outlying Islands; Vanuatu; Viet Nam; Wallis and Futuna
Bermuda; Christmas Island; Panama
Present - origin uncertain:
French Southern Territories; Madagascar; Philippines; Timor-Leste
Continuing decline in area of occupancy (AOO): Unknown
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 1800
Continuing decline in extent of occurrence (EOO): Unknown
Extreme fluctuations in extent of occurrence (EOO): No
Continuing decline in number of locations: Unknown
Extreme fluctuations in the number of locations: No
Upper elevation limit (metres): 50
Range Map: Click here to open the map viewer and explore range.

Population [top]

Current Population Trend: Stable
Additional data:
Continuing decline of mature individuals: Unknown
Extreme fluctuations: No Population severely fragmented: No
Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: No

Habitat and Ecology [top]

Habitat and Ecology: This species feeds mainly upon small fish, but will also take squid and crustaceans. The proportions vary locally, with 50% of its diet comprising of fish on Christmas Island compared to 85% on Hawaii. Prey are caught by diving. Its breeding season varies locally, nesting on coral islands, usually with vegetation, nesting in trees and bushes, on rocky slopes and cliffs, and also on artificial substrates. It lays a single egg on a bare branch, usually within a slight depression at a fork or on the midrib of a palm frond or banana leaf. It is resident year round on some islands though is a seasonal visitor on others where its non-breeding movements are not known (del Hoyo et al. 1996).
Systems: Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat: Unknown
Generation Length (years): 15.3
Movement patterns: Not a Migrant
Congregatory: Congregatory (and dispersive)

Citation: BirdLife International. 2012. Gygis alba. The IUCN Red List of Threatened Species 2012: e.T22694821A38915119. . Downloaded on 10 October 2015.
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