Gull-billed Tern
Gelochelidon nilotica
Medium-sized tern with thick black bill. Very pale overall with black cap in breeding plumage. Legs black. Nonbreeding plumage shows dark cheek patch. Found in marshier habitats than most other terns, in the Americas usually near the coast but not on the ocean (though also occasionally seen on beaches and mudflats); in Europe and Asia can also be found in wetlands well away from the coast. Rarely seen in flocks with other terns; often single or in pairs. Feeds on invertebrates and crabs in mud and marshes; often patrols the edges of ponds but does not grab fish from the water like other terns.
识别特征
This is a fairly large and powerful tern, similar in size and general appearance to a Sandwich tern, but the short thick gull-like bill, broad wings, long legs and robust body are distinctive. The summer adult has grey upperparts, white underparts, a black cap, strong black bill and black legs. The call is a characteristic ker-wik. It is 33–42 cm (13–17 in) in length and 76–91 cm (30–36 in) in wingspan. Body mass ranges from 150–292 g (5.3–10.3 oz).<p>In winter, the cap is lost, and there is a dark patch through the eye like a Forster's tern or a Mediterranean gull. Juvenile gull-billed terns have a fainter mask, but otherwise look much like winter adults.<p>Juvenile Sandwich terns have a short bill, and are frequently mistaken for gull-billed tern where the latter species is uncommon, such as North Sea coasts.
分类信息
The gull-billed tern was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with terns in the genus Sterna and coined the binomial name Sterna nilotica. Gmelin based his description on the "Egyptian tern" that had been described in 1785 by the English ornithologist John Latham in his book A General Synopsis of Birds. Latham had in turn based his own account on that by the Swedish naturalist Fredrik Hasselquist that was published in 1757. The gull-billed tern was moved to the resurrected genus Gelochelidon based on a molecular phylogenetic study published in 2005. The genus had been introduced in 1830 by the German zoologist Alfred Brehm. The genus name combines the Ancient Greek gelaō meaning "to laugh" with khelidōn meaning "swallow". The specific epithet nilotica is from Latin niloticus meaning "of the River Nile".<p>Five subspecies are recognised:
- 学名
- Gelochelidon nilotica
- 命名信息
- (Gmelin, JF, 1789)
- 目
- Charadriiformes
- 科
- Laridae
- 属
- Gelochelidon
分布与栖息地
It breeds in warmer parts of the world in southern Europe, temperate and eastern Asia, both coasts of North America, eastern South America. This bird has a number of geographical races, differing mainly in size and minor plumage details.<p>All forms show a post-breeding dispersal, but the northern breeders are most migratory, wintering south to Africa, the Caribbean and northern South America, southern Asia and New Zealand.<p>The gull-billed tern is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.
- 繁殖区
- PAL, AF, OR, NA, MA, SA : widespread inland, sw Europe to ne China; coastal China; coastal w North Atlantic and Caribbean; coastal s California and Mexico; coastal South America and inland nc Argentina
- 非繁殖区
- to subtropical and tropical coasts, rivers and lakes worldwide (except remote is.)
- 迁徙
- Complete migrants
行为
Migration pattern: Complete migrants.
保护状况
Population trend: declining.
- 种群趋势
- declining
照片
分布
鸟叫声
其他鸟类
Mottle-backed Elaenia
Elaenia gigas
Large elaenia with a striking headdress. It inhabits lightly-wooded areas, such as overgrown clearings, forest edge, and river islands, along the eastern base of the Andes. Mostly gray and olive with a yellow belly and white wingbars. Spiky white crest is frequently held erect, and is bordered by dark forehead tufts that can look like little horns. Usually found hawking insects from a conspicuous perch, and gives short, burry calls.
Eastern Yellow-billed Hornbill
Tockus flavirostris
A medium-sized black-and-white hornbill with a big downcurved “banana” bill. Males have a larger bill and pinkish bare skin on the throat; females have a smaller bill and black bare skin. Found locally in dry savanna and thornscrub. The call is a long series of deep clucks that rises and falls. Easily separated from similar black-and-white hornbills in its range by the all-yellow bill.
Tepui Redstart
Myioborus castaneocapilla
Small, active bird of highland forests. Generally yellow below and grayish above with a chestnut cap and white outer tail feathers. White eyering is more extensive in birds from western part of range, where it forms distinct spectacles. Found only in forests of the tepui highlands (above 1000 m), where typically encountered singly or in pairs. Forages actively, gleaning insects from leaves and bark or making acrobatic sallies to catch them mid-air. Usually keeps tail partially spread, revealing white outer feathers. Song is a rapid, chippering trill, recalling Tropical Parula but without strongly accented notes, and dropping slightly in pitch. Told from Slate-throated Redstart by entirely yellow underparts (including throat) and more prominent chestnut crown.
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