Slaty-backed Gull
Larus schistisagus
Thickset, short-winged, pot-bellied gull. Adult has dark gray back and wings, intense pink legs, and an especially large white “crescent” (white tertial edges) near the wingtips when perched. Breeding adult white-headed; nonbreeding birds have variably heavy brown streaking on the head and upper breast. Takes four years for immatures to progress from mostly brown to fully white and gray adult plumage; intermediate plumages are often mottled and messy. Often looks rather frosty by the first winter; starts to develop a gray back and whitish eye in its second year. Primarily an Asian species, found in coastal regions from Japan and South Korea to Russia. Regularly occurs in western Alaska, but very rare elsewhere in North America.
识别特征
It is tied with the yellow-footed gull for fourth-largest gull species, measuring 55–68.5 cm (21.7–27.0 in) in length, 132–160 cm (52–63 in) in wingspan, and 1.05–1.7 kg (2.3–3.7 lb) in weight. Among standard measurements, the wing chord is 40 to 48 cm (16 to 19 in), the bill is 4.8 to 6.5 cm (1.9 to 2.6 in), and the tarsus is 6 to 7.6 cm (2.4 to 3.0 in). It has a white head, belly, and tail with a dark slaty-gray back and wings with a broad white trailing edge. The wings and back are slightly darker than those of the western gull (Kodak grey scale 9.5 to 12 compared to Kodak 9 to 11 of the darker southern subspecies of Western Gull). On the outer primaries (p9 and p10), there are white spots called mirrors. The inner webs to primaries are pale grey, and the mid-primaries have long grey tongues tipped with large white crescents, forming a "string of pearls" pattern connecting to the broad white trailing edge of the secondaries. Its eyes are yellow surrounded by purple to deep pink orbital skin. The legs are pink and short when compared with those of similar-looking gulls, and the body appears more stout with a "pot-bellied" appearance. The bill is yellow with orange-red subterminal spot (the spot near the end of the bill that chicks peck to stimulate regurgitative feeding). Immature gulls' plumage is brown, similar to that of the great black-backed gull, but paler, and is practically indistinguishable from the immature herring gull in the field.[citation needed]
分类信息
- 学名
- Larus schistisagus
- 命名信息
- Stejneger, 1884
- 目
- Charadriiformes
- 科
- Laridae
- 属
- Larus
分布与栖息地
The Slaty-backed Gull is native to the Pacific coast of northeastern Asia. Individuals have strayed to various places throughout North America, including New England and Texas. On 3 November 2012, an individual was spotted in Finland. The species has only been spotted three times before in Europe.
- 繁殖区
- PAL : coasts and lakes of ne Siberia s of Anadyr, Kamchatka, Sea of Okhotsk, Sakhalin, Kuril Is. (e Russia), ne China, and Hokkaido and n Honshu (n Japan)
- 非繁殖区
- to coasts of Japan and Korean Pen., Bohai Sea (ne China) and Taiwan; prone to extreme vagrancy elsewhere
- 迁徙
- Complete migrants
保护状况
- 种群趋势
- unknown
照片
分布
鸟叫声
其他鸟类
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Aechmophorus clarkii
Large, long-necked grebe with very long, thin, yellow-orange bill. Black cap ends just above red eye, so the eye looks isolated in the white face. Long, gray body rides low in the water. Breeds on marshy lakes, where it builds a floating nest of vegetation. Mostly found on saltwater bays and open ocean in winter, but also lakes. Very similar to Western Grebe, with extensive range overlap and often in mixed flocks. Typically outnumbered by Western where they occur together. Clark’s looks paler overall, especially on the sides and face. Also look at the bill: brighter orange-yellow on Clark’s, lacking a dark lower edge. Some birds appear intermediate and should be left unidentified.
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