Common tern (Sterna hirundo)

French: Sterne pierregarin
GenusSterna (1)
SizeLength: 31 - 37 cm (2) (3)
Wingspan: 75 - 80 cm (2)
Weight110 - 145 g (2)

The common tern is classified as Least Concern (LC) on the IUCN Red List (1).

Known for its graceful flight and attractive plumage, the common tern (Sterna hirundo) has a smoothly rounded head and a slender body, with long, pointed wings (2) (4). In breeding plumage, the common tern has light silvery-grey upperparts, with conspicuous black outer primaries on the wingtips (2) (5) (6). A distinctive black cap covers the head and eyes, extending down to back of the neck and contrasting abruptly with the white cheeks and pale whitish-grey underparts (5) (6). The leading and trailing edges of the underwing primaries are dark and visible in flight, and a darkish wedge may be seen when the wing is spread. The tail is deeply forked, with elongated outer tail feathers. The outer edges of the tail feathers are dark grey, and the upper tail coverts are white (2) (4) (5). The bill is orange-red with a black tip and the legs are red (2) (3) (4) (5) (6). 

Outside of the breeding season, the common tern retains some of its characteristic black cap, but the forehead and face become white. The bill and legs also lose their orange-red colouration and turn black (2) (5) (6). The male and female common terns are similar in appearance year-round (2).

The juvenile common tern is variable in appearance. In general, it has a whitish or buffy forehead which contrasts with a dark brown crown and dark ear-coverts. The back, shoulders and wings are most often grey, with prominent brown bars and dark edges and tips to the feathers. The underparts are white and the tail is short, lacking the elongated streamers, with dark tips. The legs of the juvenile common tern are pinkish or orange-brown, and the bill is dark with a pinkish or yellowish base that becomes darker with age (2) (3) (6) (7). The immature common tern has a similar appearance to the adult bird, except for a whiter forehead, speckled forecrown and faint brown bars on the back. The common tern typically acquires full adult plumage in its fourth year (2) (6).  

The call of the common tern is a distinctive, harsh, rolling ‘kee-urr’ or drawled ‘kee-arr’. The juvenile common tern typically produces a grating flight call ‘krrrri’, and a persistent begging call ‘kri-kri-kri-kri’ (2) (4) (6).

The common tern is widely distributed, being found in a wide belt across most of Europe, Asia and North America (2) (4) (5) (6) (8) (9). In North America it breeds from the south central Northwest Territories to southern Quebec and Newfoundland, the Atlantic Coast from Nova Scotia to North Carolina, and at the Great Lakes and the northern Great Plains (2) (4) (6). Small numbers of the common tern may also breed in Bermuda, the Lesser Antilles and on islands off Venezuela. In Europe and Asia, the common tern breeds from the Azores and the Mediterranean coasts to northern Norway, and from the British Isles east to southern China and eastern Siberia (2) (5).

Outside of the breeding season, the common tern winters along the coasts of Central and South America, along the coast of Africa and parts of the Arabian Peninsula, and on islands throughout the Indian Ocean. The common tern is also found throughout much of Southeast Asia and Australasia (2) (8) (9).

The common tern is found in a variety of coastal and inland habitats, ranging from sea level to elevations of over 4,000 metres (8). It typically nests on sparsely vegetated islands with flat rock surfaces, open shingle or sandy beaches, sand dunes and sand spits (2) (4) (5) (8). The common tern may also nest on sandy, rocky or well-vegetated islands in estuaries, coastal lagoons, salt marshes, peninsulas and grassy cliffs (8). Further inland, the common tern nests in similar habitat, including sand or shingle lake shores and islands, and shingle bars or banks along rivers. It may also use marshes, ponds and occasionally grassy areas (8) (10).

In the non-breeding season, the common tern is found in sheltered coastal waters, estuaries and along large rivers. It may roost in harbours, on jetties, piers and beaches, and in coastal wetlands, such as lagoons, rivers, lakes, swamps, mangroves and salt marshes (4) (8). It typically forages in shallow bays, coastal waters and inlets. The common tern will also feed in freshwater, such as in lakes, ponds or rivers (2) (8).

The common tern is an opportunistic predator, feeding predominantly on small fish, as well as crustaceans, insects and, occasionally, squid or other invertebrates (2) (5) (6) (8) (9) (11) (12) (13). Pairs of common terns frequently defend small feeding territories that often consist of linear strips of shoreline (2) (5).

Like most terns, this species catches its prey by plunge-diving. The common tern first locates its prey by hovering above the surface of the water, before swooping down and either picking food from the surface or diving below to catch its prey. The common tern may also attempt to steal food from other terns (2) (5) (6) (8) (9). It is a gregarious species, and shoals of fish often attract dense feeding flocks of over 1,000 individuals (2) (8).

Breeding occurs between April and June (8). Generally the common tern will breed in a large colony of up to several thousand pairs, although some pairs do nest alone (4) (5) (6) (8) (14). It typically arrives at established breeding sites and occupies a nesting territory around 15 to 25 days before egg laying begins (2). As part of the courtship ritual, the male common tern will bend forward and scrape a small hollow into the ground with the feet, followed by the female. The pair may make several different scrapes around the nest territory before the female selects one for laying (2). Courtship feeding also plays a major part in the breeding ritual, and the male will continually offer supplies of fish to the female prior to mating (15).

Both adult common terns contribute to the construction of the nest, which is typically a shallow depression, or a small mound, in open areas close to scattered vegetation and loose substrate, such as sand, soil, gravel or shell. The scrape is lined with vegetation and other debris which is gradually added to throughout the nesting period (2) (4) (5) (6) (8).

The common tern lays a clutch of between 1 and 4 eggs, (2) (4) (5) (6) (7), which are incubated by both the male and female for around 22 to 28 days (2) (4) (5) (6). Both adults feed the young chicks, which are capable of leaving the nest a few days after hatching (5) (6) (7) (14). The rate of nest failure is relatively high for the common tern, but if the first nest is lost a pair may re-lay after 8 to 12 days. Occasionally, the common tern may raise two broods in the same season, laying and incubating a second clutch of eggs while still feeding chicks from the first brood (2) (4) (6).

A highly migratory species, the common tern leaves the breeding grounds to travel to the wintering sites soon after the chicks fledge, typically between August and October (5).

During the breeding season, the common tern is particularly vulnerable to human disturbance such as development and recreational activity close to nesting colonies, which may cause the adults to abandon the nest or chicks, as well as the flooding of nest sites. Habitat loss, largely due to coastal development, is also a major threat to the common tern, both at nesting and overwintering sites (2) (4) (8). In some areas, erosion is also proving to be a significant threat the common tern’s nesting habitat (4) (6).

Other threats to the common tern include predation by rats and other introduced terrestrial predators which prey on ground-nesting birds, as well as expanding populations of large gulls, such as the herring gull (Larus argentatus), which displace colonies of the common tern and prevent nesting (2) (4) (6) (8) (12). The common tern is also susceptible to avian influenza, and may be threatened by future outbreaks of this virus (8).

The collection of eggs and adults, and, less frequently, shooting of adult common terns for the millinery trade may pose a threat to this species in some areas (2) (12).

The common tern is listed on Annex I of the EC Directive on the Conservation of Wild Birds (16), and Appendix II of the Bern Convention (17), the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (18) and the Convention on Migratory Species (19), meaning that is afforded some legal protection. It is an offence to deliberately kill, capture or disturb this species, or to damage and destroy breeding and nesting sites (12). In North America, the common tern has been listed as Endangered, Threatened or Special Concern in most of the U.S. states around the Great Lakes (2), and it is considered to be a Species of Conservation Concern in the UK (12) (20).

In some parts of the common tern’s range, various techniques have been used to increase breeding numbers and reproductive success, including creating artificial nesting sites, managing vegetation, and protecting and enhancing existing habitat. Predator control, such as excluding mammals from around nesting colonies and preventing gulls from nesting on established common tern breeding grounds, is also a key conservation measure in some regions (2) (4) (8).

More research on the population dynamics, habitat availability, competitor relationships and food requirements of the common tern are required at the regional scale, to ensure that nesting colonies can be effectively managed and preserved in the long-term (4) (6).

Find out more about the common tern and other birds:

  1. BirdLife International:
  2. Nisbet, I.C. (2002) Common tern (Sterna hirundo). In: Poole, A. (Ed.) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:

  1. IUCN Red List (March, 2011)
  2. Nisbet, I.C. (2002) Common tern (Sterna hirundo). In: Poole, A. (Ed.) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
  3. World Register of Marine Species - Common tern (March, 2011)
  4. Hyde, D.A. (1997) Special Animal Abstract for Sterna hirundo (common tern). Michigan Natural Features Inventory, Lansing. Available at:
  5. Avibirds European Birdguide Online - Common tern (March, 2011)
  6. Kudell-Ekstrum, J. (2001) Draft Conservation Assessment for Common tern (Sterna hirundo). USDA Forest Service, Eastern Region, U.S. Available at:
  7. Cornell Lab of Ornithology: All About Birds - Common tern (March, 2011)
  8. BirdLife International - Common tern (March, 2011)
  9. British Trust for Ornithology - Common tern (March, 2011)
  10. RSPB - Common tern (March, 2011)
  11. Granadeiro, J.P., Monteiro, L.R., Silva, M.C. and Furness, R.W.  (2002) Diet of common terns in the Azores, northeast Atlantic. Waterbirds, 25(2): 149-155.
  12. Edinburgh Biodiversity Partnership. (2000) Common tern Sterna hirundo. Edinburgh Biodiversity Partnership, Edinburgh. Available at:
  13. Ahulu, A.M., Nunoo, F.K.E. and Owusu, E.H. (2006) Food preferences of the common tern, Sterna hirundo (Linnaeus, 1758) at the Densu Floodplains, Accra. West Africa Journal of Applied Ecology, 9: 1-7.
  14. Gonzalez-Solis, J., Sokolov, E. And Becker, P.H. (2001) Courtship feedings, copulations and paternity in common terns, Sterna hirundo. Animal Behaviour, 61: 1125-1132.
  15. Bird Guides - Common tern (March, 2011)
  16. EC Birds Directive (March, 2011)
  17. Council of Europe: Bern Convention (March, 2011)
  18. Agreement on the Conservation of African-Eurasian Migratory Waterbirds (March, 2011)
  19. Convention on the Conservation of Migratory Species of Wild Animals (March, 2011)
  20. Joint Nature Conservation Committee - Common tern (March, 2011)