Sterna caspia

Taxonomy

Assessment Information

Geographic Range

Habitat and Ecology

Threats

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AVES	CHARADRIIFORMES	LARIDAE

Scientific Name:

Sterna caspia

Species Authority:

Pallas, 1770

Common Name/s:

English	–	Caspian Tern
French	–	Sterne caspienne

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 appears to be increasing, 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.

History:

2008	–	Least Concern
2004	–	Least Concern

Geographic Range [top]

Range Description:	The Caspian Tern has a cosmopolitan but scattered distribution. Their breeding habitat is large lakes and ocean coasts in North America (including the Great Lakes), and locally in Europe (mainly around the Baltic Sea and Black Sea), Asia, Africa, and Australasia (Australia and New Zealand). North American birds migrate to southern coasts, the West Indies and northernmost South America. European and Asian birds winter in the Old World tropics. African and Australasian birds are resident or disperse over short distances¹.
Countries:	Native: Afghanistan; Albania; Algeria; Angola; Aruba; Australia; Austria; Azerbaijan; Bahamas; Bahrain; Bangladesh; Barbados; Belarus; Belize; Botswana; Brunei Darussalam; Bulgaria; Burkina Faso; Cambodia; Cameroon; Canada; Cayman Islands; Central African Republic; Chad; China; Colombia; Comoros; Congo; Costa Rica; Côte d'Ivoire; Cuba; Cyprus; Czech Republic; Djibouti; Dominican Republic; Egypt; El Salvador; Equatorial Guinea; Eritrea; Estonia; Ethiopia; Finland; France; French Guiana; Gabon; Gambia; Germany; Ghana; Greece; Guatemala; Guinea; Guinea-Bissau; Haiti; Honduras; Hong Kong; Hungary; India; Indonesia; Iran, Islamic Republic of; Iraq; Israel; Italy; Jamaica; Japan; Jordan; Kazakhstan; Kenya; Kuwait; Lao People's Democratic Republic; Latvia; Liberia; Libyan Arab Jamahiriya; Lithuania; Macedonia, the former Yugoslav Republic of; Madagascar; Malaysia; Maldives; Mali; Malta; Mauritania; Mayotte; Mexico; Moldova; Mongolia; Morocco; Mozambique; Myanmar; Namibia; Nepal; Netherlands; Netherlands Antilles; New Zealand; Nicaragua; Niger; Nigeria; Oman; Pakistan; Palestinian Territory, Occupied; Panama; Philippines; Poland; Portugal; Puerto Rico; Qatar; Romania; Russian Federation; Russian Federation; Russian Federation; Saint Pierre and Miquelon; Saudi Arabia; Senegal; Seychelles; Sierra Leone; Singapore; Slovakia; Somalia; South Africa; Spain; Sri Lanka; Sudan; Sweden; Switzerland; Syrian Arab Republic; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Timor-Leste; Togo; Trinidad and Tobago; Tunisia; Turkey; Turkmenistan; Turks and Caicos Islands; Uganda; Ukraine; United Arab Emirates; United States; Uzbekistan; Venezuela; Viet Nam; Western Sahara; Yemen; Zambia; Zimbabwe Vagrant: Anguilla; Antigua and Barbuda; Belgium; Bermuda; Burundi; Congo, The Democratic Republic of the; Croatia; Dominica; Ecuador; Faroe Islands; Gibraltar; Guadeloupe; Ireland; Kyrgyzstan; Luxembourg; Martinique; Montenegro; Norway; Rwanda; Saint Kitts and Nevis; Saint Lucia; Serbia; Slovenia; Swaziland; United Kingdom; Virgin Islands, U.S. Present - origin uncertain: Benin
Range Map:	Click here to open the map viewer and explore range.

Habitat and Ecology [top]

Habitat and Ecology:	Behaviour Although populations breeding near the equator are largely sedentary², northern populations are strongly migratory and disperse after breeding before migrating southwards¹. The species breeds between April and June (northern Hemisphere) or between September and December (southern Hemisphere)¹ in large dense monospecific colonies or as single pairs or small groups (2-3 pairs) amidst large colonies of other species^{1, 3, 4}. It is not a highly gregarious species outside of the breeding season⁴ but may aggregate into flocks on passage⁶, and during the winter it may feed in loose congregations¹ in rich fishing areas or at nightly roost sites⁴. Habitat The breeding, passage and wintering habitats of this species are similar, although during the winter it is largely confined to the coast¹⁰. It frequents sheltered sea coasts^{1, 4}, estuaries^{1, 2, 5}, inlets, bays, harbours⁵, coastal lagoons^{4, 5}, saltmarshes¹ and saltpans^{5, 9}, also occurring inland on fresh or saline wetlands including large lakes, inland seas^{1, 2}, large rivers^{3, 5}, creeks⁵, floodlands⁴, reservoirs^{1, 2, 5} and sewage ponds⁵. When breeding the species shows a preference for nesting on sandy, shell-strewn or shingle beaches^{3, 4}, sand-dunes, flat rock-surfaces⁴, sheltered reefs⁵ or islands^{1, 3, 4} with sparse vegetation and flat or gently sloping margins surrounded by clear, shallow, undisturbed waters⁴. It also forms winter roosts on sandbars, mudflats and banks of shell¹. Diet Its diet consists predominantly of fish 5-25 cm in length¹⁰ as well as the eggs and young of other birds, carrion¹, aquatic invertebrates³ (e.g. crayfish)¹⁰, flying insects^{6, 10} and earthworms¹⁰. Breeding site The nest is a shallow depression in the sand, gravel, shells, sparse vegetation¹ or dried mud² of ridges, beaches^{3, 4, 5}, dunes⁴, flat rocky or stony islets, banks⁵, islands or reefs in seas, lakes and large rivers³, dredge spoil piles and islands in reservoirs⁵. The species nests in large colonies or as single pairs or small groups amidst colonies of other species, neighbouring nests placed between 0.7 and 4 m part¹. The species may forage up to 60 km from the site of the breeding colony¹. Management information Management for this species should include a number of measures such as habitat and vegetation management, the use of artificial nest substrates, predator management (e.g. control of gull populations) and the minimisation of disturbance¹⁰. Habitat and vegetation management may include the creation of artificial islands with calm water on their leeward side to allow the growth of submerged vegetation and fish spawning habitats, or alternatively the creation of floating artificial nesting-rafts (e.g. barges covered with sand)¹⁰.
Systems:	Terrestrial; Freshwater; Marine

Habitat and Ecology:

Behaviour Although populations breeding near the equator are largely sedentary², northern populations are strongly migratory and disperse after breeding before migrating southwards¹. The species breeds between April and June (northern Hemisphere) or between September and December (southern Hemisphere)¹ in large dense monospecific colonies or as single pairs or small groups (2-3 pairs) amidst large colonies of other species^{1, 3, 4}. It is not a highly gregarious species outside of the breeding season⁴ but may aggregate into flocks on passage⁶, and during the winter it may feed in loose congregations¹ in rich fishing areas or at nightly roost sites⁴. Habitat The breeding, passage and wintering habitats of this species are similar, although during the winter it is largely confined to the coast¹⁰. It frequents sheltered sea coasts^{1, 4}, estuaries^{1, 2, 5}, inlets, bays, harbours⁵, coastal lagoons^{4, 5}, saltmarshes¹ and saltpans^{5, 9}, also occurring inland on fresh or saline wetlands including large lakes, inland seas^{1, 2}, large rivers^{3, 5}, creeks⁵, floodlands⁴, reservoirs^{1, 2, 5} and sewage ponds⁵. When breeding the species shows a preference for nesting on sandy, shell-strewn or shingle beaches^{3, 4}, sand-dunes, flat rock-surfaces⁴, sheltered reefs⁵ or islands^{1, 3, 4} with sparse vegetation and flat or gently sloping margins surrounded by clear, shallow, undisturbed waters⁴. It also forms winter roosts on sandbars, mudflats and banks of shell¹. Diet Its diet consists predominantly of fish 5-25 cm in length¹⁰ as well as the eggs and young of other birds, carrion¹, aquatic invertebrates³ (e.g. crayfish)¹⁰, flying insects^{6, 10} and earthworms¹⁰. Breeding site The nest is a shallow depression in the sand, gravel, shells, sparse vegetation¹ or dried mud² of ridges, beaches^{3, 4, 5}, dunes⁴, flat rocky or stony islets, banks⁵, islands or reefs in seas, lakes and large rivers³, dredge spoil piles and islands in reservoirs⁵. The species nests in large colonies or as single pairs or small groups amidst colonies of other species, neighbouring nests placed between 0.7 and 4 m part¹. The species may forage up to 60 km from the site of the breeding colony¹. Management information Management for this species should include a number of measures such as habitat and vegetation management, the use of artificial nest substrates, predator management (e.g. control of gull populations) and the minimisation of disturbance¹⁰. Habitat and vegetation management may include the creation of artificial islands with calm water on their leeward side to allow the growth of submerged vegetation and fish spawning habitats, or alternatively the creation of floating artificial nesting-rafts (e.g. barges covered with sand)¹⁰.

Systems:

Terrestrial; Freshwater; Marine

Threats [top]

Major Threat(s):	The species is currently threatened by the loss and deterioration of breeding habitat through accelerated vegetation succession (possibly through the introduction of exotic plant species)¹⁰ and may be threatened in the future by habitat loss through inundation as a result of sea-level rise¹⁰. The species is vulnerable to human disturbance at nesting colonies⁸ especially during the early-courtship and incubation periods¹⁰, and exposure to bioaccumulated contaminants (e.g. organochlorines or methylmercury) in fish could be lowering the species's reproductive success¹. Newcastle disease^{7, 10} and avian botulism may also threaten concentrated local populations (although these diseases are unlikely to threaten the global population as a whole)¹⁰.

Major Threat(s):

The species is currently threatened by the loss and deterioration of breeding habitat through accelerated vegetation succession (possibly through the introduction of exotic plant species)¹⁰ and may be threatened in the future by habitat loss through inundation as a result of sea-level rise¹⁰. The species is vulnerable to human disturbance at nesting colonies⁸ especially during the early-courtship and incubation periods¹⁰, and exposure to bioaccumulated contaminants (e.g. organochlorines or methylmercury) in fish could be lowering the species's reproductive success¹. Newcastle disease^{7, 10} and avian botulism may also threaten concentrated local populations (although these diseases are unlikely to threaten the global population as a whole)¹⁰.

Citation:	BirdLife International 2009. Sterna caspia. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 04 February 2012.
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