White-winged Tern

White-winged Tern
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Charadriiformes
Family:	Sternidae
Genus:	Chlidonias
Species:	C. leucopterus
Binomial name
Chlidonias leucopterus (Temminck, 1815)

The White-winged Tern, or White-winged Black Tern, Chlidonias leucopterus, is a small tern generally found in or near bodies of fresh water across from Southeastern Europe east to Australia.

The name 'White-winged Tern' is the standard in most English-speaking countries; in Britain, this name is also the one used by the formal ornithological recording authorities, but the older alternative 'White-winged Black Tern' is still frequent in popular use.

Description

Adult birds in summer have short red legs and a short black bill (small and stubby, meausuring 22–25 mm from the feathers, decidedly shorter than the head), a black neck (often with a pale gray back) and belly, very dark grey back, with a white rump and light grey (almost white) tail, which often looks 'square' in juveniles. The face is tinged yellowish. The wings, as the name implies, are mainly white. The inner wing is grayish with brown-tipped coverts. In non-breeding plumage, most of the black is replaced by white or pale grey, though a few blackish feathers may be retained, admixed with white underparts. A good deal of black shows in the underwing-coverts. The head is black, with a white forehead. The crown is blackish-brown, flecked with white, and the hindcrown is blackish with a certain amount of white flecking. These white markings are pronounced in the winter adult. There is a dark triangular patch forward of the eye. The collar is fairly broad and white. In juveniles and moulting adults, the rump is pale gray, becoming grey in both phases late in the year. The clear white collar and rump isolate the mantle as a dark brown 'saddle'. The mantle feathers have narrow paler brown tips, as have the tertials and scapulars.

Hybridisation with Black Tern

Hybridisation between this species and Black Tern has been recorded from Sweden^[2] and the Netherlands.^[3] Two juvenile birds at Chew Valley Lake, England, in September 1978 and September 1981, were also believed to be hybrids; they showed mixed characters of the two species, specifically a combination of a dark mantle (a feature of White-winged Black) with dark patches on the breast-side (a feature of Black Tern, not shown by White-winted Black).^[4][5]

Distribution and habitat

Their breeding habitat is freshwater marshes across from southeast Europe to central Asia. They usually nest either on floating vegetation in a marsh or on the ground very close to water, laying 2-4 eggs in a nest built of small reed stems and other vegetation. In winter, they migrate to Africa, southern Asia and Australia. It is a scarce vagrant in North America, mainly on the Atlantic coast, but a few records on the Pacific coast and inland in the Great Lakes area.

Photographed at Kazinga Channel, Uganda

Behaviour

Like the other "marsh" terns (Chlidonias), and unlike the "white" (Sterna) terns, these birds do not dive for fish, but fly slowly over the water to surface-pick items on the surface and catch insects in flight. They mainly eat insects and small fish. In flight, the build appears thick-set. The wing-beats are shallow and leisurely.

The White-winged Tern is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

References

1. ^ BirdLife International (2004). Chlidonias leucopterus. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006. Database entry includes justification for why this species is of least concern
2. ^ (Swedish) Alexandersson, H. (1979) En hybridisering mellan vitvingad tärna Childonias leucopterus och svarttärna Childonias niger på Öland 1978 Calidris 8: 151-53
3. ^ (Dutch) Van IJzendoorn, E. J. (1980) Broedgeval van Zwarte Childonias niger × Witvleugelstern C. leucopterus Dutch Birding 2: 62-65
4. ^ Vinicombe, Keith (1980) Tern showing mixed characters of Black Tern and White-winged Black Tern British Birds 73(5): 223-25
5. ^ Davis, A. H. (1980) Tern showing mixed characters of Black and White-winged Black Tern British Birds 75(12): 579-80

• "National Geographic" Field Guide to the Birds of North America ISBN 0-7922-6877-6
• Seabirds, an Identification Guide by Peter Harrison, (1983) ISBN 0-7470-1410-8
• Handbook of the Birds of the World Vol 3, Josep del Hoyo editor, ISBN 84-87334-20-2

External links

• White-winged Tern (Chlidonias leucopterus)