Saunders's Tern
Sternula saundersi
Tiny, pale coastal tern. Has a yellow bill and neat black head markings in breeding plumage, and a dark bill and messier head markings in non-breeding plumage. Found on coastal sand bars and mudflats, and sometimes on the open ocean. Extremely similar to Little Tern. In breeding plumage, Saunders’s Tern can be identified by the fact that the small white patch on its forehead is squared off and doesn’t extend behind the eye. In non-breeding plumage, the two species may be indistinguishable.
识别特征
Saunders's tern shares many of the features of its close relative, the little tern, including a white body, a black-tipped yellow bill, and a black cap with a white forehead patch. In its breeding plumage, it distinguishes itself with a straight-bordered forehead patch, possessing more black outer primaries, and duskier colored legs and feet in comparison to the bright yellow legs of the little tern. In non-breeding plumage, the two are very similar.<p>Saunders's tern is 20–28 cm (8-11 in) long, weighs 40-45 grams, and possesses a wingspan of 50-55 cm(20-21 in). It has an average wing length of 16.6 cm(6.5 in), an average bill length of 2.8 cm(1.1 in), and a tail fork depth of about 2.8 cm(1.1 in) on average.
分类信息
Saunders's tern was first described in 1877 by British botanist and ornithologist Allan Octavian Hume during his stay in British India as part of the Imperial Civil Service. It was originally given the name black-shafted ternlet (Sterna saundersi) by Hume, which was later changed to its present common name.<p>It is considered by some to be a subspecies of Sternula albifrons, potentially of a larger species group, or otherwise conspecific.
- 学名
- Sternula saundersi
- 命名信息
- (Hume, 1877)
- 目
- Charadriiformes
- 科
- Laridae
- 属
- Sternula
分布与栖息地
- 繁殖区
- AF, PAL : islands of Red Sea and Persian Gulf, off Somalia and Socotra, patchily to coast of Pakistan, nw India, and Adam's Bridge is. (between India and Sri Lanka)
- 非繁殖区
- to coastal Tanzania, all Seychelles groups and Madagascar (tropical w Indian Ocean), Chagos Arch. and Maldives (nc Indian Ocean)
- 迁徙
- Complete migrants
行为
The majority of the Saunders's tern's diet consists of various marine animals, including small fish, crustaceans, and mollusks. It will also eat several varieties of insects. An individual will hover above the water for a sizable amount of time, before making a plunge dive to catch fish.<p>
保护状况
- 种群趋势
- declining
照片
分布
鸟叫声
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