The black tern (Chlidonias niger) is a small tern generally found in or near inland water that breeds in Europe, Western Asia and North America. In winter the birds migrate to coastal areas of Africa and South America.

Taxonomy

The black tern was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae under the binomial name Sterna nigra. Linnaeus specified the type location as Europe but it is now restricted to Uppsala in Sweden. The black tern is now one of four species placed in the genus Chlidonias that was introduced in 1822 by the French naturalist Constantine Rafinesque. The genus name is from Ancient Greek khelidonios, "swallow-like", from khelidon, "swallow": another old English name for the black tern is "carr (i.e. lake) swallow". The species name is from Latin niger "shining black". As its name suggests, it has predominantly dark plumage. In some lights it can appear blue in the breeding season, hence the old English name "blue darr".

Two subspecies are recognised. These are listed below with their breeding ranges. and the Netherlands. 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-winged black).

Distribution and habitat

Their breeding habitat is freshwater marshes across most of Canada, the northern United States and much of Europe and western Asia. They usually nest either on floating material in a marsh or on the ground very close to water, laying 2–4 eggs.

In England the black tern was abundant in the eastern Fens, especially in Lincolnshire and Cambridgeshire, until the early nineteenth century. The Welsh naturalist Thomas Pennant, describing a visit made to Lincolnshire in 1769, referred to 'vast flocks' of black terns that 'almost deafen one with their clamors'. Extensive drainage of its breeding grounds wiped out the English population by about 1840. Intermittent attempts by the black tern to recolonise England have proved unsuccessful, with only a handful of English breeding records, and one in Ireland, in the second half of the twentieth century.

North American black terns migrate to the coasts of northern South America, some to the open ocean. Old World birds winter in Africa.

<!-- Image with unknown copyright status removed: thumb|242px|Adult North American black tern in fall plumage -->

Unlike the "white" Sterna terns, these birds do not dive for fish, but forage on the wing picking up items at or near the water's surface or catching insects in flight. They mainly eat insects and fish as well as amphibians.

Vagrancy

The American race has occurred as a vagrant in Britain and in Ireland.

Conservation

The North American population has declined in recent times due to loss of habitat.

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

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Image:Black Tern RWD.jpg|Nonbreeding

Image:Black Tern RWD8.jpg|Eclipse breeding

Image:Mustviiresed.jpg|Black terns mating in Tartu County, Estonia

Image:Chlidonias niger MWNH 2170.JPG|Egg, Collection Museum Wiesbaden, Germany

File:Black Tern chick with band and 2 eggmates, St. Clair Flats, 21 July 2014 (14710858471).jpg|A newly hatched chick and two eggs on a nest made of floating reeds, in Ontario, Canada

Chlidonias niger niger MHNT.ZOO.2010.11.132.9.jpg| Chlidonias niger niger - MHNT

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References

  • Black Tern - Chlidonias niger - USGS Patuxent Bird Identification InfoCenter
  • Black Tern Species Account - Cornell Lab of Ornithology
  • Black Tern Species text in The Atlas of Southern African Birds