The common tern (Sterna hirundo) belongs to the family of gulls and terns, the Laridae.
The common tern species is distributed in Europe, Asia, North America, South America, Africa, Arabian Peninsula, India, southeast Asia and Australia. These tern species are strongly migratory birds. These terns are polytypic species.
Appearance, physical description and identification
The common tern (Sterna hirundo) is a medium-sized tern, measuring 30 to 40 cm in length and weighing 100 to 150 grams. The wingspan is 70 to 80 cm.The breeding common terns have pale gray upperparts and whitish underparts. The forehead and crown are black. The rump and tail are white. In non-breeding adults the forehead is white. The juveniles have brown crown and nape.
The bill is long and pointed. The base of the bill is reddish and the distal end is blackish. The irises are blackish. The legs and feet are orange-red. The call of these tern species is a loud repeated "keeur..keeur" or "kyar..kyar"sound.
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| 1.Birds of India - Image of Common tern - Sterna hirundo by U.S. Fish and Wildlife Service Northeast Region |
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| 2.Indian birds - Picture of Common tern - Sterna hirundo by Tiia Monto |
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| 3.Birds of India - Photo of Common tern - Sterna hirundo by U.S. Fish and Wildlife Service Northeast Region |
Origin, geographical range and distribution
The common tern nominate subspecies S. h. hirundo is distributed in North America, South America, Atlantic islands, Europe, west Asia, north and west Africa, Middle East and the regions around Black and Caspian Seas. They winter south of Tropic of Cancer.The common tern subspecies S. h. minussensis is distributed in central Asia and Mongolia. They winter in northern Indian Ocean.
The subspecies S. h. tibetana is distributed at high altitudes in west Mongolia, south central China and northwest India. It winters in eastern Indian Ocean.
The common tern subspecies S. h. longipennis is distributed in Siberia, northern Mongolia and northeast China. It winters in eastern Indian Ocean, southeast Asia and Australia.
The Important Bird and Biodiversity Areas (IBA) of these common tern species in China are, Aksu River basin, Ulungur Hu and Jili Hu, Oasis, Desert and Wetland at Mosuowan, Desert and wetland from Northern Urumqi to Dabancheng and Bosten Lake.
Some of the IBA of these common terns in Russia are, Yeiski salt-lakes, Khanskoye Lake, Kamsko-Ikski area, Beglitskaya sand-spit, Lower Ob', Saltosarayskoye lake, Dvuob'ye, Ulukhkol' lake, Selenga delta, Nevskoye Lake, Man'yass lake and Kurtan Lake.
The IBA of these terns in USA are, Isles of Shoals and Great Gull Island. The IBA in Thailand is Na Muang Krabi. The IBA in South Africa are, West Coast National Park and Saldanha Bay islands, Richards Bay Game Reserve and Orange River Mouth Wetlands.
Ecosystem and habitat
These common tern species do not normally occur in forests. They normally occur in altitudes from 0 to 4000 meters.The natural ecosystems and habitats of these common tern species include inland wetlands, freshwater lakes, rivers, streams, creeks, estuaries, mudflats, marine lakes, brackish water lakes, lagoons, open seas, beaches, sea cliffs and rocky offshore islands.
Diet and feeding behavior
The diet of this common tern consists mainly of small fish. Planktonic crustaceans, small squids, aquatic insects, small fish like sand lances, Neotropical silversides, sardines and killifish are their primary food.These common tern species feed by plunge-diving for fish in freshwater bodies as well as in seas. They may circle or hover before diving for the prey. They may submerge for a few seconds and usually do not dive deep.
Reproduction and breeding habits
The breeding season of these common terns is from April to June in most of their breeding range. These species are monogamous and breed in large colonies. They are territorial. They make aerial courtship displays.The breeding sites include coastal cliffs, offshore islands, sandy beaches, dunes, gravel-pits, flat rock surfaces and inshore islands. The nest is a shallow scrape on an open substrate.
The common tern clutch contains three to six pale greenish or buff colored eggs with dark mottling. Both the parents incubate the eggs and take care of the young. The chicks hatch out after 21 days and fledge after 25 days.
Migration and movement patterns
These common tern species are mostly migratory birds. The breeding populations in central Asia, North America and Europe move southwards beyond the Tropic of Cancer for wintering.These common tern species leave their breeding grounds between August and October and migrate southwards for wintering. The return migration to the breeding grounds takes place in March and April.
Common tern - Quick Facts
- Scientific name: Sterna hirundo
- Species author: Linnaeus, 1758
- Synonyms/Protonym: Sterna Hirundo Linnaeus, 1758
- Family: Laridae › Charadriiformes › Aves › Chordata › Animalia
- Vernacular names: English: Common tern, Chinese: 普通燕鸥, French: Sterne pierregarin, German: Flussseeschwalbe, Spanish: Charrán común, Russian: Речная крачка, Japanese: アジサシ, Indonesian: Dara-laut biasa
- Other names: Black-billed Common Tern, Common Tern
- Distribution: Europe, Asia, North America, South America, coast of Africa, Arabian Peninsula, coast of India, southeast Asia, Australia
- Diet and feeding habits: small fish, sand lances, Neotropical silversides, killifish
- IUCN status listing: Least Concern (LC)
Conservation and survival
The global population size of the common tern (Sterna hirundo) is estimated to be about 1,600,000 to 3,600,000 individual birds. The overall population trend of the species is not known.In most of its range, this tern species is reported to be uncommon to common. The generation length is 11.5 years. Its distribution size is about 112,000,000 sq.km.
Habitat alteration and destruction, ecosystem modifications, pollution, human intrusions and disturbance, hunting for food are the main threats that are endangering the survival of these tern species.
IUCN and CITES status
The common tern (Sterna hirundo) 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.The IUCN (International Union for Conservation of Nature) has categorized and evaluated the tern species and has listed it as of "Least Concern".
The CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) status is ‘Not Evaluated’ for the common tern (Sterna hirundo).
| Taxonomy and scientific classification of Sterna hirundo | |
|---|---|
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Charadriiformes |
| Family: | Laridae |
| Subfamily: | - |
| Genus: | Sterna |
| Species: | S. hirundo |
| Binomial name: | Sterna hirundo |
| IUCN status listing: |
 Least Concern |
The four recognized subspecies of the common tern (Sterna hirundo) are: S. h. hirundo Linnaeus, 1758, S. h. minussensis Sushkin, 1925, S. h. tibetana H. Saunders, 1876 and S. h. longipennis Nordmann, 1835.
1.Photo source: https://www.flickr.com/photos/usfwsnortheast/5974497409/in/photostream/ (cropped)
Photo author: U.S. Fish and Wildlife Service Northeast Region | License: Public domain
2.Photo source: https://en.wikipedia.org/wiki/File:Sterna_hirundo_in_Finland.jpg (cropped)
Photo author: Tiia Monto | License: CC BY-SA 3.0
3.Photo source: https://www.flickr.com/photos/usfwsnortheast/5975057796/ (cropped)
Photo author: U.S. Fish and Wildlife Service Northeast Region | License: Public domain
Current topic in Birds of India: Common tern - Sterna hirundo.
