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Sterna hirundo

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AVES CHARADRIIFORMES LARIDAE

Scientific Name: Sterna hirundo
Species Authority: Linnaeus, 1758
Common Name/s:
English Common Tern
French Sterne pierregarin
Taxonomic Notes: The BirdLife Taxonomic Working Group is aware that phylogenetic analyses have been published which have proposed generic rearrangements which may affect this species, but prefers to wait until work by other taxonomists reveals how these changes affect the entire groups involved.

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/s: Ekstrom, J., Butchart, S., Malpas, L., Calvert, R., Hatchett, J.
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). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable 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.

Geographic Range [top]

Range Description: The Common Tern has a circumpolar distribution and can be found breeding in most of Europe, Asia and North America except the extreme north and south. It winters further south, being found along the coast and inland of South America down to the Falkland Islands (Islas Malvinas), along the coast of Africa excluding the north, along parts of the Arabian Peninsula and the whole coast of India, and throughout much of south-east Asia and Australasia (excluding New Zealand) (del Hoyo et al. 1996).
Countries:
Native:
Afghanistan; Albania; Algeria; Angola (Angola); Anguilla; Antigua and Barbuda; Argentina; Armenia (Armenia); Aruba; Australia; Austria; Azerbaijan; Bahamas; Bahrain; Bangladesh; Barbados; Belarus; Belgium; Belize; Benin; Bermuda; Bhutan; Bolivia, Plurinational States of; Bonaire, Sint Eustatius and Saba; Bosnia and Herzegovina; Brazil; Brunei Darussalam; Bulgaria; Cambodia; Cameroon; Canada; Cape Verde; Cayman Islands; Chile; China; Colombia; Congo; Congo, The Democratic Republic of the; Costa Rica; Côte d'Ivoire; Croatia; Cuba; Curaçao; Cyprus; Czech Republic; Denmark; Djibouti; Dominica; Dominican Republic; Ecuador; Egypt; El Salvador; Equatorial Guinea; Eritrea; Estonia; Falkland Islands (Malvinas); Faroe Islands; Finland; France; French Guiana; Gabon; Gambia; Georgia; Germany; Ghana; Gibraltar; Greece; Grenada; Guadeloupe; Guam; Guatemala; Guinea; Guinea-Bissau; Guyana; Haiti; Honduras; Hong Kong; Hungary; India; Indonesia; Iran, Islamic Republic of; Iraq; Ireland; Israel; Italy; Japan; Jordan; Kazakhstan; Kenya; Korea, Democratic People's Republic of; Korea, Republic of; Kuwait; Kyrgyzstan; Latvia; Lebanon; Liberia; Libya; Lithuania; Luxembourg; Macedonia, the former Yugoslav Republic of; Madagascar; Malaysia; Mali; Malta; Marshall Islands; Martinique; Mauritania; Mauritius; Mexico; Micronesia, Federated States of ; Moldova; Mongolia; Montenegro; Montserrat; Morocco; Mozambique; Myanmar; Namibia; Nepal; Netherlands; New Caledonia; Nicaragua; Nigeria; Northern Mariana Islands; Norway; Oman; Pakistan; Palau; Palestinian Territory, Occupied; Panama; Papua New Guinea; Peru; Philippines; Poland; Portugal; Puerto Rico; Qatar; Réunion; Romania; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Pierre and Miquelon; Saint Vincent and the Grenadines; Saudi Arabia; Senegal; Serbia (Serbia); Seychelles; Sierra Leone; Singapore; Sint Maarten (Dutch part); Slovakia; Slovenia; Solomon Islands; Somalia; South Africa; South Georgia and the South Sandwich Islands; Spain; Sri Lanka; Sudan; Suriname; Sweden; Switzerland; Syrian Arab Republic; Taiwan, Province of China; Tajikistan; Tanzania, United Republic of; Thailand; Timor-Leste; Togo; Trinidad and Tobago; Tunisia; Turkey; Turkmenistan; Turks and Caicos Islands; Ukraine; United Arab Emirates; United Kingdom; United States (Georgia); Uruguay; Uzbekistan; Vanuatu; Venezuela, Bolivarian Republic of; Viet Nam; Virgin Islands, British; Virgin Islands, U.S.; Western Sahara; Yemen
Vagrant:
Cocos (Keeling) Islands; Comoros; Cook Islands; Fiji; Iceland; Jamaica; Liechtenstein; Malawi; Maldives; New Zealand; Paraguay; Zambia
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The global population is estimated to number c.1,600,000-4,600,000 individuals (Wetlands International 2006), while national population sizes have been estimated at c.10,000-100,000 breeding pairs, c.1,000-10,000 individuals on migration and c.50-1,000 wintering individuals in China and c.10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in Russia (Brazil 2009).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Behaviour This species is a strongly migratory coastal seabird (del Hoyo et al. 1996, Snow and Perrins 1998). It breeds between April and June in solitary pairs or colonially in groups of up to several thousand pairs (inland colonies often smaller and more widely-dispersed than coastal ones) (del Hoyo et al. 1996). Palearctic breeders migrate south after breeding between August and October, returning to the breeding grounds in March or April (del Hoyo et al. 1996). The species may moult on arrival in its the wintering grounds (e.g. the Caribbean), during which it may become vulnerable to human exploitation (van Halewyn and Norton 1984). It is gregarious throughout the year (Snow and Perrins 1998) and shoals of fish may attract dense feeding flocks, although it otherwise feeds singly or in small loose groups (del Hoyo et al. 1996, Snow and Perrins 1998). In some cases, it is territorial; in Massachusetts, feeding territories usually consist of linear strips of shoreline which are occupied and defended regularly by both members of a pair. The prevalence of territoriality at feeding sites varies between colonies and is related to food species availability (Nisbet 1983). Most individuals forage 5-10 km from breeding colonies, occasionally feeding at sea 15 km offshore (del Hoyo et al. 1996). Common Terns forage over fresh water as well as marine habitats, and often follow predatory fish , waiting for panicking baitfish to surface. They sometimes forage in mixed-species flocks together with other terns (Safina 1990, Brenninkmeijer et al. 2002). Habitat Breeding The species breeds in a wide variety of habitats in coastal and inland areas from sea-level to heights of greater than 4,000 m (del Hoyo et al. 1996). Along the coast it shows a preference for nesting on flat rock surfaces on inshore islands (Snow and Perrins 1998), open shingle and sandy beaches, dunes and spits (del Hoyo et al. 1996, Snow and Perrins 1998), vegetated inter-dune areas, sandy, rocky, shell-strewn or well-vegetated islands in estuaries (del Hoyo et al. 1996)and coastal lagoons (Snow and Perrins 1998), saltmarshes (Richards 1990, Snow and Perrins 1998), mainland peninsulas (Snow and Perrins 1998) and grassy plateaus atop coastal cliffs (del Hoyo et al. 1996). Inland it may nest in similar habitats including sand or shingle lakes shores (Richards 1990), shingle banks in rivers (Snow and Perrins 1998), sandy, rocky, shell-strewn or well-vegetated islands in lakes and rivers (del Hoyo et al. 1996, Snow and Perrins 1998), sand- or gravel-pits (Richards 1990, Snow and Perrins 1998), marshes, ponds, grassy areas and patches of dredged soil (Snow and Perrins 1998). Non-breeding The species winters on sheltered coastal waters (Higgins and Davies 1996), estuaries and along large rivers, occupying harbours, jetties, piers, beaches (del Hoyo et al. 1996) and coastal wetlands including lagoons, rivers, lakes, swamps and saltworks, mangroves and saltmarshes (Higgins and Davies 1996). During this season it roosts on unvegetated sandy beaches, shores of estuaries or lagoons, sandbars and rocky shores (Higgins and Davies 1996). Diet The species is opportunistic, its diet consisting predominantly of small fish and occasionally planktonic crustaceans and insects (del Hoyo et al. 1996). Breeding site The nest is a shallow depression on open substrates with little or no vegetation placed near a vertical object (e.g. rock, shell, plant or artefact) to provide shelter for chicks and to facilitate nest identification (del Hoyo et al. 1996). Nest sites include the edges of bare sand amongst vegetation, rocks or logs, open areas on the margins of vegetation on beaches, the edges of mats of vegetation in marshes (del Hoyo et al. 1996), and grassy or rocky substrates on rocky islets (del Hoyo et al. 1996). The species will also readily nest on artificial rafts (del Hoyo et al. 1996). Foraging range Studies have observed foraging birds at up to 37 km from the nearest colony (Cramp 1985, BirdLife International 2000). However, although Common Terns tend to range further than Roseate Terns (BirdLife International 2000), most are observed within 10 km of a breeding colony (Becker et al. 1993, Wanless et al. 1998, Newton and Crowe 1999). At various sites, visual observations e.g. of direction of flight also suggest that most feeding trips are to sites within 10 km of the colony (Hopkins and Wiley 1972, Duffy 1986, Uttley et al. 1989, Burness et al. 1994, BirdLife International 2000), although birds in these studies were recorded at a maximum of 18 km from the colony (Duffy 1986). Radio-tagging at the Wadden Sea has shown that birds forage at a mean radius of at least 6.3 km (Becker et al. 1993), although the total distance travelled by individuals on these foraging trips is much greater, around 26-30 km. In Massachusetts, feeding territories tend to be located in shallow water up to 75 m from shore, and may be at least 8.5 km away from the breeding colony (Lemmetyinen 1973, Nisbet 1983, BirdLife International 2000), as well as areas where depth changes abruptly and tidal currents are strong, which presumably produces much upwelling and mixing of cold, deep water with warmer surface water (Safina 1990). Birds lower the rate at which they attempt to forage when windspeed is high (Taylor 1983).
Systems: Terrestrial; Freshwater; Marine

Threats [top]

Major Threat(s): During the breeding season the species is vulnerable to human disturbance at nesting colonies (Buckley and Buckley 1984, Blokpoel and Scharf 1991) (e.g. from off-road vehicles, recreation, motor-boats, personal watercraft and dogs) (van Halewyn and Norton 1984, del Hoyo et al. 1996, Hyde 1997, Burger 1998), and to the flooding of nest sites as a result of naturally fluctuating water levels (Buckley and Buckley 1984, del Hoyo et al. 1996, Hyde 1997). On its breeding grounds the species is also threatened by habitat loss as a result of coastal developement (Buckley and Buckley 1984, Blokpoel and Scharf 1991, del Hoyo et al. 1996, Hyde 1997), erosion (Hyde 1997), vegetation overgrowth (rapid vegetation succession encroaching upon nesting habitats) (Blokpoel and Scharf 1991, del Hoyo et al. 1996, Hyde 1997), and chemical pollution (which may also result in eggshell thinning) (Blokpoel and Scharf 1991, del Hoyo et al. 1996, Hyde 1997). It suffers predation at nesting colonies from rats (especially on islands) (Buckley and Buckley 1984, del Hoyo et al. 1996) and from expanding populations of large gull species (Brown and Nettleship 1984, del Hoyo et al. 1996) such as Herring Gulls Larus argentatus (Buckley and Buckley 1984) (gulls may also prevent the species from nesting in the area by colonising it first) (Blokpoel and Scharf 1991, del Hoyo et al. 1996). The species is susceptible to avian influenza so may be threatened by future outbreaks of the virus (Melville and Shortridge 2006). Utilisation The species is harvested semi-commercially on its wintering grounds in the Caribbean (van Halewyn and Norton 1984, del Hoyo et al. 1996).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
Management techniques used to increase the breeding numbers and reproductive success of the species in the Great Lakes region of North America include creating artificial nesting sites, vegetation management, enhancement of existing nesting habitat, using models and vocalisation to attract breeding pairs and predator control (e.g. mammal-exclusion, destruction of gull nests, direct predator removal, or preventative measures against gull nesting) (Blokpoel and Scharf 1991). A conservation scheme for the protection of gull and tern breeding colonies in coastal lagoons and deltas (e.g. Po Delta, Italy) involves protection from human disturbance, prevention of erosion of islet complexes, habitat maintenance and the creation of new islets for nest sites (Fasola and Canova 1996). The scheme particularly specifies that bare islets with 30-100 % cover of low vegetation (sward heights less than 20 cm) should be maintained or created as nesting sites (Fasola and Canova 1996). Artificial nesting rafts have proved effective in promoting breeding success in areas where there is a lack of suitable nesting habitat or where human disturbance is a particular threat (1996) (del Hoyo et al. 1996). Using fire to expose the ground surface in areas where vegetation succession is proceeding too far towards closed vegetation stages has been successful in some areas (Hyde 1997). Culling predatory gulls can be an effective management tool to enhance breeding productivity (Guillemette and Brousseau 2001), although some management plans recommend non-lethal harassment techniques that target gulls (e.g. egg and nest destruction, conspicuous human observers, gull displacement walks, and pyrotechnics) to reduce predation on nesting colonies rather than culling (Donehower et al. 2007).

Citation: BirdLife International 2012. Sterna hirundo. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 20 April 2014.
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