Caspian Tern

识别特征

It is the world's largest tern with a length of 48–60 cm (19–24 in), a wingspan of 127–145 cm (50–57 in) and a weight of 530–782 g (18.7–27.6 oz). Adult birds have black legs, and a long thick red-orange bill with a small black tip. They have a white head with a black cap and white neck, belly, and tail. The upper wings and back are pale grey; the underwings are pale with dark primary feathers. In-flight, the tail is less forked than other terns, and wingtips are black on the underside. In winter, the black cap is still present (unlike many other terns), but with some white streaking on the forehead. The call is a loud heron-like croak.<p>

分类信息

Genus: Hydroprogne; Family: Laridae; Order: Charadriiformes.

学名

Hydroprogne caspia

命名信息

(Pallas, 1770)

目

Charadriiformes

科

Laridae

属

Hydroprogne

分布与栖息地

Their breeding habitat is large lakes and ocean coasts in North America (including the Great Lakes), and locally in Europe (mainly around the Baltic Sea and Black Sea), Asia, Africa, and Australasia (Australia and New Zealand). North American birds migrate to southern coasts, the West Indies and northernmost South America. European and Asian birds spend the non-breeding season in the Old World tropics. African and Australasian birds are resident or disperse over short distances.<p>In 2016, a nest of the Caspian tern was found in the Cape Krusenstern National Monument in northwestern Alaska, 1,000 miles further north than any previous sighting. This development was part of a general trend in Alaska of species moving to the north, a tendency ascribed to global warming.<p>The global population is about 50,000 pairs; numbers in most regions are stable, but the Baltic Sea population (1400–1475 pairs in the early 1990s) is declining and of conservation concern.<p>The Caspian tern is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

繁殖区

PAL, OR, AU, NA : patchily coastal Baltic Sea and inland se Europe to w Mongolia and Ussuriland (se Russia) and ne China and s Asian coasts; coastal and inland w and s Africa; Europa (w of s Madagascar, Mozambique Channel), coastal Madagascar and Aldabra group (sw Seychelles); coastal Australia and New Zealand (North, South and Stewart is.) and inland n, e Australia; inland Northwest Territories to c California, Great Lakes and ne Canada

非繁殖区

coastal Africa, Red Sea, Persian Gulf, India, Thailand, Malay Pen. and Vietnam; e Pacific and Caribbean to Panama

迁徙

Complete migrants

行为

Migration pattern: Complete migrants.

保护状况

Population trend: rising.

种群趋势

rising