Little tern (Sterna albifrons)

Synonyms: Sternula albifrons
  
French: Sterne naine
KingdomAnimalia
PhylumChordata
ClassAves
OrderCharadriiformes
FamilyLaridae
GenusSterna (1)
SizeLength: 20 - 28 cm (2)
Wingspan: 45 - 55 cm (2)
Weightc. 50 g (2)

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

A small, migratory seabird, the little tern (Sterna albifrons) is slender, with a streamlined body, narrow, sharp-pointed wings and a deeply forked tail (2) (3) (4) (5) (6). In breeding plumage, the little tern has a neat black cap and a tapering stripe between the bill and the eye. A triangular patch of white is visible on the forehead, and the rest of the head and neck are white. The upperparts of the little tern are pale grey, contrasting with the entirely white underparts. The outer primaries are usually slightly darker grey, and a white line runs along their upper edge, with a thin black line visible across the bottom edge. In flight, a thin black band is visible on the edge of the wing. During the breeding season, the little tern has a bright yellow bill with a small black tip, black eyes, and bright yellow-orange legs and feet (5) (6).

Outside of the breeding season, the distinctive black cap of the little tern becomes smaller, and the crown and forehead become more grey-white. Dark spots on the back of the crown merge with a dark band which extends from in front of the eyes to the back of the neck. The rump and tail are pale grey, and the tail is less deeply forked. The bill changes from yellow to black, and the legs and feet become duller orange-brown (4) (5). 

The juvenile little tern is very similar to the non-breeding adult, but the black band on the head is narrower and duller. The forehead and crown are washed with brown, while narrow white scaling and brown, U-shaped markings are distinctly visible on the shoulders and the back. The tail is marked with a thin dark band. The bill of the juvenile is dark brown with a blackish tip (6).

A widespread but patchily distributed species, the little tern occurs throughout Europe, Africa, the Middle East, Asia and Australasia (6) (7).

During the breeding season, the little tern ranges throughout Europe, southern, eastern and south-eastern Asia, Indonesia and Australasia. It migrates outside of the breeding season, expanding its range to include most of the coast of Africa, the Arabian Peninsula and the western Indian and Pacific Oceans (6) (7).

Generally found in sheltered coastal environments, the little tern commonly inhabits lagoons, estuaries, river mouths and deltas, lakes, bays, harbours and inlets. It may also be found further inland, sometimes up to several kilometres from the sea (2) (4) (7).

The little tern typically nests on barren or sparsely vegetated beaches, islands and spits composed of sand, shingle, shell fragments, pebbles, rocks or coral fragments. It may also nest on dry mudflats in grassy areas, on wide, flat or gently sloping sandy ocean beaches, and also occasionally in sand-dunes. On rare occasions, the little tern may be recorded on offshore islands or coral cays (2) (4) (5) (6) (7).

Outside of the breeding season, the little tern inhabits tidal creeks, coastal lagoons and saltpans (5) (6) (7).

Foraging primarily during the day, the little tern usually feeds at low tide on small fish and crustaceans, as well as insects, annelid worms and molluscs (2) (4) (5) (6) (7). This species generally forages singly, or in small, loose flocks, although it may congregate in large groups of many thousands of individuals where food is particularly abundant (6) (7).

The little tern most often hunts for prey in the shallow waters of channels, estuaries and lagoons, in the surf on beaches, or along the line of the advancing tide (2) (4) (5) (6) (7) (8). Typically, it catches its prey by plunging into water from around three to ten metres above the surface, after first hovering above the water to seek out prey (2) (5) (6) (8). The little tern will frequently seek out shoals of small ‘bait fish’, which attract larger predatory fish, performing rapid vertical plunge-dives to capture its prey before the fish disperse (8). The little tern may also glean prey from the surface of the water, and may take insects from vegetation while in flight (5) (6) (8).

The little tern generally breeds between May and July in Europe and Asia, and around April in Africa (5) (7). In Australia, the little tern has an extended breeding season from April to early January in the Northern Territory, and from late August to January or February in the east (6). It usually breeds in solitary pairs or in small groups of up to around 15 pairs, although it is occasionally reported to form much larger breeding colonies (7).

The male little tern initiates the courtship ritual by presenting a fish to the female (3). The nest is a bare scrape or shallow depression on the ground, usually on beaches of sand, pebbles, shingle, shell fragments, coral fragments or rock above the high tide-line (3) (4) (6) (7) (9). It may sometimes nest in more marshy habitats, close to estuaries, or adjacent to coastal lakes (4) (7). Both adults incubate the clutch of 1 to 3 well-camouflaged eggs, for a period of 17 to 22 days (2) (3) (4) (6) (9). The little tern chicks are fed with a liquid mix of fish for around three days, after which the adults bring back small whole fish that are fed to the juveniles head first (3). Both adults actively defend the nest against intruders during the fledgling period, which lasts for between 17 and 22 days (2) (4) (9).

The primary threat to the little tern is the destruction of its habitat through increasing coastal development. This species is also highly vulnerable to human disturbance at its nesting sites, which may lead to complete breeding failure in some locations (6) (7). The little tern has a naturally low breeding success rate, and natural events such as the loss of eggs and chicks to predation, flooding of nesting sites (including by high tides) and adverse weather conditions all further contribute to the high levels of breeding failure in this ground-nesting species (2) (4) (7).

Additional threats to the little tern include pesticide pollution, local egg collection and disease (2) (7).

The little tern is afforded some protection by several key pieces of international conservation legislation. It is listed on Appendix I of the EU Birds Directive (10), and is included in Appendix II of the Bern Convention on the Conservation of European Wildlife and Natural Habitats (11), the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (12) and the Convention on Migratory Species (13).

In the UK, the little tern is listed on Schedule 1 of the UK Wildlife and Countryside Act, 1981. The little tern is also listed in Australia as an Endangered Species on Schedule 1 of the New South Wales Threatened Species Conservation Act, 1995 and the Commonwealth Endangered Species Protection Act, 1992 (2) (7) (14).

Recommended conservation measures for the little tern include the use of fences and warning signs around nesting sites to prevent human disturbance and predation by feral species such as cats, as well as warden patrols to protect and monitor sensitive sites. Additionally, creating artificial nest sites, preventing erosion of islet complexes and maintaining areas of suitable nesting habitat may help improve the reproductive success of the little tern (2) (4) (7).

Find out more about the little tern and other bird species:

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:
arkive@wildscreen.org.uk

  1. IUCN Red List (March, 2011)
    http://www.iucnredlist.org/
  2. New South Wales National Parks and Wildlife Service. (1999) Threatened Species Information: Little tern (Sterna albifrons). Threatened Species Unit, Hurstville, New South Wales. Available at:
    http://www.environment.nsw.gov.au/resources/nature/tsprofileLittleTern.pdf
  3. Cheah, J.W.K. and Ng. A. (2008) Breeding ecology of the little tern, Sterna albifrons. Nature in Singapore, 1: 69-73.
  4. New South Wales Department of Environment and Conservation: Threatened Species – Little tern profile (March, 2011)
    http://www.threatenedspecies.environment.nsw.gov.au/tsprofile/profile.aspx?id=10769
  5. Avibirds European Birdguide - Little tern (March, 2011)
    http://www.avibirds.com/euhtml/Little_Tern.html
  6. Australian Government: Department of Sustainability, Environment, Water, Population and Communities - Little tern (March, 2011)
    http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=813
  7. BirdLife International (March, 2011)
    http://www.birdlife.org/datazone/speciesfactsheet.php?id=3276
  8. Cyrus, D.P. (1991) The influence of turbidity on the foraging behaviour of little terns Sterna albifrons off the St Lucia mouth, Zululand, South Africa. Marine Ornithology, 19: 103-108.
  9. Lim, J.C.W. (2009) First two days in the life of a little tern Sterna albifrons (Aves: Sternidae). Nature in Singapore, 2: 307-310.
  10. EC Birds Directive (March, 2011)
    http://www.jncc.gov.uk/page-1373
  11. Council of Europe: Bern Convention (March, 2011)
    http://conventions.coe.int/Treaty/EN/Treaties/Html/104.htm
  12. Agreement on the Conservation of African-Eurasian Migratory Waterbirds (March, 2011)
    http://www.unep-aewa.org/
  13. Convention on the Conservation of Migratory Species of Wild Animals (March, 2011)
    http://www.cms.int/
  14. UNEP-WCMC (March, 2011)
    http://www.unep-wcmc.org/