Thalasseus maximus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Charadriiformes Laridae

Scientific Name: Thalasseus maximus (Boddaert, 1783)
Common Name(s):
English Royal Tern
French Sterne royale
Sterna maxima Boddaert, 1783
Thalasseus maximus Stotz et al. (1996)
Thalasseus maximus AOU checklist (1998 + supplements)
Taxonomic Source(s): Cramp, S. and Simmons, K.E.L. (eds). 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
Taxonomic Notes: Thalasseus maximus (del Hoyo and Collar 2014) was previously placed in the genus Sterna as S. maxima.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Butchart, S., Calvert, R., Ekstrom, J. & Malpas, L.
This species has a very 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:

Geographic Range [top]

Range Description:The Royal Tern is found in the Americas and the Atlantic coast of Africa. In Africa is breed from Mauritania to Guinea, ranging in winter from Morocco to Namibia. In the Americas it breeds from southern California (USA) to Sinaloa (Mexico), from Maryland to Texas (USA), through the West Indies to the Guianas and possibly Brazil, on the Yucatan Peninsula, in south Brazil, Uruguay and north Patagonia (Argentina). It winters from Washington (USA) south to Peru on the western coast, and from Texas to south Brazil on the eastern side (del Hoyo et al. 1996).
Countries occurrence:
Angola; Anguilla; Antigua and Barbuda; Argentina; Aruba; Bahamas; Barbados; Benin; Bermuda; Bonaire, Sint Eustatius and Saba (Saba, Sint Eustatius); Brazil; Cameroon; Canada; Cayman Islands; Colombia; Congo; Congo, The Democratic Republic of the; Costa Rica; Côte d'Ivoire; Cuba; Curaçao; Dominica; Dominican Republic; Ecuador; El Salvador; Equatorial Guinea; French Guiana; Gabon; Gambia; Ghana; Grenada; Guadeloupe; Guatemala; Guinea; Guinea-Bissau; Guyana; Haiti; Honduras; Jamaica; Liberia; Martinique; Mauritania; Mexico; Montserrat; Morocco; Namibia; Nicaragua; Nigeria; Panama; Peru; Puerto Rico; Saint Barthélemy; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Vincent and the Grenadines; Senegal; Sierra Leone; Sint Maarten (Dutch part); Suriname; Togo; Trinidad and Tobago; Turks and Caicos Islands; United States; Uruguay; Venezuela, Bolivarian Republic of; Virgin Islands, British; Virgin Islands, U.S.; Western Sahara
Belize; Gibraltar; Ireland; Norway; Paraguay; Portugal; Spain; Sudan; United Kingdom
Present - origin uncertain:
Chile; Mozambique
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:73800000
Continuing decline in extent of occurrence (EOO):UnknownExtreme 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):100
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:NoPopulation severely fragmented:No
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:Behaviour This species undergoes post-breeding dispersive movements northwards before migrating southwards for the winter (del Hoyo et al. 1996). It breeds between April and June (Richards 1990) in dense colonies of 100-4,000 pairs often near colonies of Laughing Gull Larus atricilla and Sandwich Tern Sterna sandvicensis (del Hoyo et al. 1996). The species may also nest singly amidst colonies of other tern species (del Hoyo et al. 1996). It usually feeds singly or in small flocks and roosts gregariously even outside of the breeding season (del Hoyo et al. 1996). Habitat Breeding For breeding the species shows a preference for inaccessible sites including barren sandy beaches, islands in saltmarsh, dredge spoil and coral islands surrounded by shallow water and with a high degree of visibility, no mammalian predators and little vegetation (del Hoyo et al. 1996). It also forages along estuaries, in lagoons and in mangroves during this season, mostly within 100 m of the shore but up to 40 km from the breeding colony (del Hoyo et al. 1996). Non-breeding Outside of the breeding season the species forages within 100 m of the land along sheltered coasts in estuaries, harbours and river mouths, sometimes also foraging a short distance inland along broad rivers (del Hoyo et al. 1996). Diet Its diet consists predominantly of small fish 3-18 cm long as well as squid, shrimps and crabs (del Hoyo et al. 1996). Breeding site The nest is a simple scrape (del Hoyo et al. 1996) in sand (Urban et al. 1986) in inaccessible sites surrounded by shallow water near the mouths of bays with a high degree of visibility, no mammalian predators and little vegetation (del Hoyo et al. 1996). Management information The preferred breeding sites of this species are often vulnerable to flooding (del Hoyo et al. 1996).
Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):11.2
Movement patterns:Full Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s): The species is potentially threatened by the contamination of large prey with pesticides (through bioaccumulation in the food chain) (del Hoyo et al. 1996). It has also suffered dramatic declines over the past 25 years in California due to the disappearance of its staple prey (the Pacific sardine) through overfishing (del Hoyo et al. 1996). Utilisation Egg-collecting is known to occur at breeding colonies of this species (del Hoyo et al. 1996, Del Viejo et al. 2004).

Citation: BirdLife International. 2016. Thalasseus maximus. The IUCN Red List of Threatened Species 2016: e.T22694542A93456904. . Downloaded on 22 July 2018.
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