Sterna fuscata

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AVES	CHARADRIIFORMES	LARIDAE

Scientific Name:

Sterna fuscata

Species Authority:

Linnaeus, 1766

Common Name/s:

English	–	Sooty Tern
French	–	Sterne fuligineuse

Assessment Information [top]

Red List Category & Criteria:

Least Concern ver 3.1

Year Assessed:

2009

Assessor/s:

BirdLife International

Reviewer/s:

Bird, J., Butchart, S.

Justification:
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 is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely 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.

History:

2008	–	Least Concern
2004	–	Least Concern

Geographic Range [top]

Range Description:	The Sooty Tern breeds on tropical islands and ranges through most of the tropical oceans¹.
Countries:	Native: American Samoa; Anguilla; Antigua and Barbuda; Argentina; Aruba; Australia; Bahamas; Barbados; Belize; Bermuda; Brazil; British Indian Ocean Territory; Cameroon; Canada; Cayman Islands; Chile; China; Cocos (Keeling) Islands; Colombia; Comoros; Cook Islands; Costa Rica; Cuba; Djibouti; Dominica; Dominican Republic; Ecuador; El Salvador; Equatorial Guinea; Fiji; French Guiana; French Polynesia; French Southern Territories (the); Grenada; Guadeloupe; Guam; Guatemala; Guyana; Haiti; Honduras; India; Indonesia; Iran, Islamic Republic of; Jamaica; Japan; Kenya; Kiribati; Korea, Republic of; Liberia; Madagascar; Malaysia; Maldives; Marshall Islands; Martinique; Mauritania; Mauritius; Mayotte; Mexico; Montserrat; Mozambique; Myanmar; Nauru; Netherlands Antilles; New Caledonia; New Zealand; Nicaragua; Nigeria; Norfolk Island; Northern Mariana Islands; Oman; Palau; Panama; Papua New Guinea; Peru; Philippines; Pitcairn; Puerto Rico; Réunion; Saint Helena; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Vincent and the Grenadines; Samoa; Sao Tomé and Principe; Senegal; Seychelles; Solomon Islands; Somalia; South Africa; Sri Lanka; Suriname; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Tokelau; Tonga; Trinidad and Tobago; Turks and Caicos Islands; Tuvalu; United States; United States Minor Outlying Islands; Vanuatu; Venezuela; Viet Nam; Virgin Islands, British; Virgin Islands, U.S.; Yemen Vagrant: Bahrain; Belgium; Cape Verde; Christmas Island; Côte d'Ivoire; Denmark; Eritrea; France; Germany; Ghana; Hong Kong; Iceland; Israel; Italy; Malawi; Norway; Portugal; Saudi Arabia; Sierra Leone; Spain; Sudan; Swaziland; Sweden; Tunisia; United Arab Emirates; United Kingdom; Zimbabwe Present - origin uncertain: Angola; Bangladesh; Benin; Cambodia; Congo; Congo, The Democratic Republic of the; Gabon; Gambia; Guinea; Guinea-Bissau; Iraq; Kuwait; Namibia; Niue; Pakistan; Singapore; Timor-Leste; Togo; Wallis and Futuna
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	Total regarded as a minimum by Wetlands International (2006).

Population:

Total regarded as a minimum by Wetlands International (2006).

Habitat and Ecology [top]

Habitat and Ecology:	Behaviour The species is dispersive and migratory². At most colonies adults leave for the open sea after breeding¹ and become strongly pelagic² for 2-3 months before returning to the breeding grounds¹. On returning to the breeding colonies they continue to forage pelagically by day and settle on land at night for a further 2-3 months before beginning to breed¹. The timing of breeding varies throughout the species's range, with nesting occurring all year round at some colony sites but seasonally at others¹. The species nests in very large colonies¹ and remains gregarious throughout the year (congregating in small to large flocks to feed at sea) although it may be observed singly². Habitat Breeding It breeds on flat, open, sparsely or heavily vegetated, oceanic or barrier islands of sand, coral or rock in productive tropical and subtropical offshore waters rich in plankton, fish and squid¹. It is absent from cold current areas and generally avoids islands with terrestrial predators¹. Non-breeding Outside of the breeding season the species is highly pelagic but generally avoids cold current areas¹. Diet Its diet consists predominantly of fish up to 18 cm long (usually 6-8 cm) and squid, but it also occasionally takes crustaceans, insects and offal¹. The species is reliant upon prey driven to the surface by predatory fish (e.g. tuna, Scombidae), especially when breeding². Breeding site The nest is a slight depression¹ or scrape on the ground². It shows a preference for nesting on flat, bare sand, coral grit or shell^{1, 2} amongst low vegetation^{1, 2} on beaches above the high-water mark² or on coral islands, atolls and sandbanks². Less often it may nest on rock stacks or other offshore islets, and on ledges or terraces of cliffs (although it avoids sheer cliff-faces)². It nests in dense colonies within which neighbouring nests may be placed c.50 cm apart¹. Higher nesting densities occur in areas where bare ground predominates but which are vegetated with plants greater than or equal to 15 cm tall⁸. Management information The mortality of the species was significantly reduced on Isla Isabel (a densely forested tropical island off the Pacific coast of Mexico) by the eradication of introduced domestic cats Felis catus using a combination of poisoning, trapping and hunting with firearms⁷. The nesting density and therefore the number of breeding pairs was increased in colonies on Bird Island by clearing areas of dense native or introduced vegetation and burning existing colony areas annually to prevent the growth of woody plants⁸.
Systems:	Terrestrial; Marine

Habitat and Ecology:

Behaviour The species is dispersive and migratory². At most colonies adults leave for the open sea after breeding¹ and become strongly pelagic² for 2-3 months before returning to the breeding grounds¹. On returning to the breeding colonies they continue to forage pelagically by day and settle on land at night for a further 2-3 months before beginning to breed¹. The timing of breeding varies throughout the species's range, with nesting occurring all year round at some colony sites but seasonally at others¹. The species nests in very large colonies¹ and remains gregarious throughout the year (congregating in small to large flocks to feed at sea) although it may be observed singly². Habitat Breeding It breeds on flat, open, sparsely or heavily vegetated, oceanic or barrier islands of sand, coral or rock in productive tropical and subtropical offshore waters rich in plankton, fish and squid¹. It is absent from cold current areas and generally avoids islands with terrestrial predators¹. Non-breeding Outside of the breeding season the species is highly pelagic but generally avoids cold current areas¹. Diet Its diet consists predominantly of fish up to 18 cm long (usually 6-8 cm) and squid, but it also occasionally takes crustaceans, insects and offal¹. The species is reliant upon prey driven to the surface by predatory fish (e.g. tuna, Scombidae), especially when breeding². Breeding site The nest is a slight depression¹ or scrape on the ground². It shows a preference for nesting on flat, bare sand, coral grit or shell^{1, 2} amongst low vegetation^{1, 2} on beaches above the high-water mark² or on coral islands, atolls and sandbanks². Less often it may nest on rock stacks or other offshore islets, and on ledges or terraces of cliffs (although it avoids sheer cliff-faces)². It nests in dense colonies within which neighbouring nests may be placed c.50 cm apart¹. Higher nesting densities occur in areas where bare ground predominates but which are vegetated with plants greater than or equal to 15 cm tall⁸. Management information The mortality of the species was significantly reduced on Isla Isabel (a densely forested tropical island off the Pacific coast of Mexico) by the eradication of introduced domestic cats Felis catus using a combination of poisoning, trapping and hunting with firearms⁷. The nesting density and therefore the number of breeding pairs was increased in colonies on Bird Island by clearing areas of dense native or introduced vegetation and burning existing colony areas annually to prevent the growth of woody plants⁸.

Systems:

Terrestrial; Marine

Threats [top]

Major Threat(s):	Some colonies (e.g. on Ascension Island)¹ are threatened by predation from introduced rats and domestic cats Felis catus⁷, and the species has been displaced from nesting colonies on Bird Island by invasive ants Anoplolepis longipes⁵. Persistent large scale egg-collecting in some areas has encouraged the species to move to suboptimal nesting sites, resulting in higher mortality and reduced reproductive success⁴. It may also be threatened by climatic change, as variations in sea-surface temperature have been shown to negatively influence the species's foraging success at breeding colonies (hence lowering reproductive success)⁶. The species is vulnerable to oil pollution from oil spills and tankers transporting fuel¹ and is threatened by reductions in the global populations of tuna (a result of over-fishing) due to it's dependence on tuna to force prey to the surface³. Utilisation The eggs of this species are harvested in many areas (e.g. Caribbean)^{4, 1}.

Major Threat(s):

Some colonies (e.g. on Ascension Island)¹ are threatened by predation from introduced rats and domestic cats Felis catus⁷, and the species has been displaced from nesting colonies on Bird Island by invasive ants Anoplolepis longipes⁵. Persistent large scale egg-collecting in some areas has encouraged the species to move to suboptimal nesting sites, resulting in higher mortality and reduced reproductive success⁴. It may also be threatened by climatic change, as variations in sea-surface temperature have been shown to negatively influence the species's foraging success at breeding colonies (hence lowering reproductive success)⁶. The species is vulnerable to oil pollution from oil spills and tankers transporting fuel¹ and is threatened by reductions in the global populations of tuna (a result of over-fishing) due to it's dependence on tuna to force prey to the surface³. Utilisation The eggs of this species are harvested in many areas (e.g. Caribbean)^{4, 1}.

Citation:	BirdLife International 2009. Sterna fuscata. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 07 February 2012.
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