Little Tern (Sternula albifrons)

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[edit] Little Tern (Sternula albifrons) Pallas, 1764

The Little Tern (Sternula albifrons) is considered as a one of the smallest terns of the world.

[edit] Taxonomy

The Little Tern (Sternula albifrons) belongs to family Sternidae. It was formerly placed into the genus Sterna, which now is restricted to the large white terns. The former North American (S. a. antillarum) and Red Sea S. a. saundersi subspecies are now considered to be separate species, the Least Tern (Sternula antillarum) and Saunders's Tern (Sternula saundersi). There are three subspecies, the nominate albifrons occurring in Europe to North Africa and western Asia; guineae of western and central Africa; and sinensis of East Asia and the north and east coasts of Australia (Higgins and Davies, 1996).

Class: Aves
Order: Charadriiformes
Family: Sternidae
Genus: Sterna
Species: Sternula albifrons
Subspecies: Sternula albifrons albifrons
Subspecies: Sternula albifrons guineae
Subspecies: Sternula albifrons sinensis

[edit] Distribution

Its distribution includes all continents. The Little Tern breeds in North America, Eurasia, Western Africa and Australasia and winters in northern South America, Africa, Southern Asia and Australasia. It is strongly migratory, wintering in the subtropical and tropical oceans as far south as South Africa and Australia.

[edit] Physical Characteristics

The Little Tern is a small, slender, migratory or partly migratory seabird. Its length is 20–28cm and its wingspan is 45–55cm. Pale grey upperparts contrast with the white chest, underbelly and the moderately long, deeply forked tail. The Little Tern has a black cap and black outer wing-edges. During breeding the bill and legs change from black to yellow, and a black wedge appears from the bill to the eye. During non-breeding, the Little Tern’s black cap shrinks to a black nape and its bill becomes black. The wing tips are two-toned grey to black on the outer primaries (flight feathers). The sexes are similar and immature birds are similar to non-breeding adults with upper wings and back mottled grey and brown. The Little Tern is also known as the Black-lored Tern, the Sea Swallow, or the White-shafted Ternlet. Habitat: The Little Tern is mainly coastal bird, being found on beaches, sheltered inlets, estuaries, lakes, sewage farms, lagoons, river mouths and deltas, especially where exposed sandbanks or sand spits occur.. Almost exclusively coastal, preferring sheltered environments; however may occur several kilometers from the sea in harbors, inlets and rivers. Breeding habitat includes sand spits or islets in sheltered coastal environments such as estuaries and inlets, and also sandy ocean beaches, with nests occasionally built in sand dunes. It may also occasionally nest on coral cays and on the bank of salt pans.

[edit] Diet

The Little Tern eats small fish, insects, crustaceans and other invertebrates. It prefers to feed over shallower coastal waters and can hover briefly with the body horizontal and the bill pointing down, before plunging into the water to catch prey.

[edit] Behavior

The little tern usually feeds in small groups, although it often roosts in large flocks on beaches or sand spits with other terns. It is very active and noisy; its usual flight call is an excited, high-pitched ‘kweek’. Its alarm call is an urgent ‘tee-eep, tee-eep, tee-eep’. The little tern flies with deep, rapid wing beats and hovers rapidly with wings held in steep ‘V’ before it plunges into the water while feeding. Breeding colonies are surprisingly unobtrusive and easily overlooked. The Little Tern is extremely sensitive to human disturbance when breeding. Litte tern are often seen feeding in flocks, foraging for small fish, crustaceans, insects, annelids and mollusks by plunging in the shallow water of channels and estuaries, and in the surf on beaches, or skipping over the water surface with a swallow-like flight.

[edit] Breeding

Little Tern Nests in small, scattered colonies in low dunes or on sandy beaches just above high tide mark near estuary mouths or adjacent to coastal lakes and islands. The nest is a scrape in the sand, which may be lined with shell grit, seaweed or small pebbles. Both parents incubate up to three well-camouflaged eggs for up to 22 days, aggressively defending the nest against intruders until the young fledge at 17 - 19 days.

[edit] References

• The Clements Checklist of Birds of the World: James F. Clements, Jared Diamond, John W. Fitzpatrick.
• Wetlands International Waterbird Population Estimates - Fourth Edition.
• Ali, S. & Ripley, D. (1964-74 ) Handbook of the Birds of India & Pakistan (Vols. 1-10). Bombay: OUP
• Grimmet, R Inskipp, T., & Inskipp, C. (1998) Birds of the Indian Subcontinent. UK: A&C Black.
• Inskipp, T. et al. (1996) An Annotated Checklist of the Birds of the Oriental Region. Sandy, UK: OBC.
• Kazmierczak, K. & van Perlo, B. (2000) A Field-Guide to the Birds of the Indian Subcontinent. UK: Pica Press
• BirdLife International (2004).
• IUCN Red List of Threatened Species. IUCN 2006
• Bridge, E. S.; Jones, A. W. & Baker, A. J. (2005): A phylogenetic framework for the terns (Sternini) inferred from mtDNA sequences: implications for taxonomy and plumage evolution. Molecular Phylogenetics and Evolution
• Harrison, Peter (1988): Seabirds (2nd edition). Christopher Helm, London
• Peterson, R.T., Mountfort, G. & Hollom, P.A.D. (1993) Collins Field Guide- Birds of Britain and Europe.

Arpit Deomurari
Consultant (Environment, GIS and IT)
deomurari@gmail.com