The Caspian tern (Hydroprogne caspia) belongs to the family of terns, Sternidae.
These tern species have a worldwide distribution, occurring in Asia, Indian subcontinent, Africa, Europe, North America and Australia. The Caspian tern is the world's largest among Sternidae. These Caspian terns are monotypic species.
Caspian tern - Overview
- Scientific name: Hydroprogne caspia
- Species author: (Pallas, 1770)
- Synonyms/Protonym: Sterna caspia Pallas, 1770, Hydroprogne tschegrava, Helopus caspius
- Family: Sternidae › Charadriiformes › Aves › Chordata › Animalia
- Vernacular names: English: Caspian tern, Chinese: 红嘴巨鸥, French: Sterne caspienne, German: Raubseeschwalbe, Spanish: Pagaza piquirroja, Russian: Чеграва, Japanese: オニアジサシ, Malay: Burung Camar Batu Berumbai
- Other names: Taranui
- Distribution: North America, Europe, central and west Asia, Africa, Indian subcontinent, Southeast Asia, Australia, New Zealand
- Diet and feeding habits: fish, crabs, shrimp, mollusks, large insects, eggs of birds, hatchlings of birds, rodents
- IUCN status listing: Least Concern (LC)
Appearance, physical description and identificationThe Caspian tern (Hydroprogne caspia) is the largest tern, measuring 50 to 55 cm in length and weighing 570 to 780 grams. The wingspan is 130 to 140 cm.
The whitish head has a black cap in the breeding populations and has gray streaking in non-breeding terns. The neck, throat, belly, tail, undertail are white. The upper wings and back are pale gray. The underwings are whitish with dark primary feathers and wing tips.
The Caspian tern has a large, stout, orange-red bill with a black tip. The tail is slightly forked. The feet are black. The irises are black. The call of these terns is a distinctive harsh croaking "krree-ahk" sound.
|Birds of India - Image of Caspian tern - Hydroprogne caspia|
|Indian birds - Picture of Caspian tern - Hydroprogne caspia by USFWS Mountain-Prairie|
|Birds of India - Photo of Caspian tern - Hydroprogne caspia|
Origin, geographical range and distributionThe Caspian tern species are distributed in North America, Central America, northmost South America, Africa, Europe, Asia, Indian subcontinent, Australia and New Zealand. Though have a cosmopolitan distribution, the occurrence of terns is scattered. The distribution is predominantly associated with marine coasts, very large inland water bodies and large river systems.
The Important Bird and Biodiversity Areas (IBA) for the Caspian tern species in Canada are, Lake St. Martin Islands, Limestone Islands, Little George Island, The Watchers, The Cousins, Spruce Island Reef, Pigeon Island, Sand Reef Islands and Presqu'ile Provincial Park.
Some of the Important Bird and Biodiversity Areas (IBA) for the Caspian tern species in Sweden are Rödkallen – Söräspen Islands, Archipelago and coastline of North-East Scania, Lövsta Bight – Björn Archipelago, Archipelago of Östergötland, Lake Tämnaren, Archipelago of Stockholm and Lake Storhjälmaren.
Some of the Important Bird and Biodiversity Areas (IBA) for the Caspian tern species in Russia are Chanovskaya lake system, Yeiski salt-lakes, Delta of the Kuban' river, Valaamski archipelago, Delta of the River Don, Mouth of Samur river and Dolgy Reef and Bol'shoi Fiskar archipelagos.
Some of the Important Bird and Biodiversity Areas (IBA) for the Caspian tern species in Finland are Eckerö and Hammarland archipelago, Tammisaari and Inkoo western archipelago, Itäinen Suomenlahti National Park, Pori archipelago and wetlands, Kirkon-Vilkkiläntura Bay and Kristiinankaupunki southern archipelago.
Ecosystem and habitatThese Caspian tern species do not normally occur in forest. These species occur in altitudes from 0 to 100 meters. They inhabit artificial ecosystems like large water storage lakes and reservoirs. The natural ecosystems include marine and wetland systems.
Coastal brackish and marine lakes, marshes, estuaries, shallow seas with submerged macroalgae like kelp and seagrass, subtidal rocks, reefs, pebbles and gravel, freshwater lakes, peatlands, seasonal lakes and inland seas are some of the habitats of Caspian terns.
Diet and feeding behaviorThe diet of these Caspian terns is mostly fish. Crabs, shrimps, molluscs, crayfish, fish, aquatic worms, large insects are their primary food. They plunge dive and catch their prey. They are known to scavenge and eat offal and carrion. They also predate on the eggs and nestlings of other birds.
Reproduction and breeding habitsThe breeding season of these Caspian tern species is from April to June in North America, Europe and central Asia. In Australia these birds breed throughout the year. The terns in rest of the Southern Hemisphere breed from September to December.
These Caspian tern species may breed in dense colonies or as small groups among colonies of other species. The nest is a shallow scrape in sand, gravel or shingle located on dried mud, beaches, dunes, banks and islands in seas, large lakes and large rivers.
The typical tern clutch consists of one to three sparsely spotted eggs. The incubation lasts for 28 days. The plumage pattern of the hatchlings is variable. The chicks may fledge after 40 days. The Caspian tern parents may forage up to 60 km from the breeding site to feed the chicks.
Migration and movement patternsThe Caspian tern is a partially migratory bird. The populations in parts of East Africa, Madagascar, Sri Lanka, Coastal Pakistan, southwest Afghanistan, east coastal China, Australia and New Zealand are resident. Post breeding, the tern juveniles may disperse and establish in new locations within the range.
The North American Caspian tern populations migrate southward, wintering in southern parts of North America, Central America, West Indies and northmost parts of Venezuela and Colombia. The tern populations in Europe, central and western Asia are highly migratory, wintering in tropics and subtropics of Africa and India.
Conservation and survivalThe global population size of the Caspian tern (Hydroprogne caspia) is estimated to be around 250,000 to 470,000 individual birds. The overall population trend of these tern species is considered to be increasing. Throughout its range it is reported to be very common. The generation length is 12.2 years. Their distribution size is about 226,000,000 sq.km.
The Caspian tern (Hydroprogne caspia) does not approach the thresholds for being Vulnerable, either under the range size criterion, or under the population trend criterion, or under the population size criterion. Human disturbances at the breeding grounds, avian diseases, oil-spills, marine pollution and hunting for food are the main threats that may endanger the survival of these tern species.
IUCN and CITES statusThe IUCN (International Union for Conservation of Nature) has categorized and evaluated the Caspian tern species and has listed it as of "Least Concern". CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) status is ‘Not Evaluated’ for the Caspian tern (Hydroprogne caspia).
1.Image source: https://commons.wikimedia.org/wiki/File:Caspian_Tern_(Hydroprogne_caspia)_RWD.jpg
Image author: Dick Daniels (http://carolinabirds.org/) | License: CC BY-SA 3.0
2.Image source: https://commons.wikimedia.org/wiki/File:Caspian_Tern,_Bear_River_Migratory_Bird_Refuge,_Utah_(22726623439).jpg
Image author: USFWS Mountain-Prairie | License: CC BY 2.0
3.Image source: https://commons.wikimedia.org/wiki/File:Two_caspian_terns.png
Image author: Dmitry Mikhirev | License: CC BY-SA 3.0
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